Polygraph Testing During Pregnancy: Expert Guide

The Short Answer

There is no absolute prohibition against polygraph testing during pregnancy. However, the overwhelming consensus among experienced examiners is that pregnancy significantly compromises the accuracy and reliability of the test, and most professionals will recommend deferring the examination until after delivery.

Polygraph testing relies on measuring subtle changes in three primary physiological channels: cardiovascular activity (blood pressure, pulse rate, and pulse amplitude), respiratory patterns (rate, depth, and regularity of breathing), and electrodermal activity (sweat gland response measured through skin conductance). According to the APA Standards of Practice (amended August 2024), examiners should make reasonable efforts to determine that an examinee is a suitable candidate, and medical conditions observable by or reasonably known to the examiner should be considered when conducting and evaluating an examination [1]Verified APA Standards of Practice (Amended August 2024)
Confirms examiners should make reasonable efforts to determine suitability and consider medical conditions when conducting examinations. Each of these channels is substantially altered during pregnancy, making it difficult for the examiner to distinguish between physiological responses caused by relevant test questions and those caused by the pregnant person's altered baseline physiology.

Importantly, peer-reviewed research published in the European Polygraph journal by Marcin Gołaszewski (2014) demonstrated that polygraph examination of pregnant women is feasible with appropriate accommodations, including modified break schedules and sensor placement adjustments [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves. This means that while challenging, pregnancy does not automatically disqualify an individual from polygraph examination — it requires an experienced examiner who can make appropriate adaptations.

For a general understanding of who can take a lie detector test, our suitability guide covers the full range of conditions examiners evaluate.

A Profound Systemic Transformation

Pregnancy is a profound systemic transformation that affects virtually every organ system in the body. These changes are not pathological — they are normal, necessary adaptations to support the growing fetus. But from the perspective of a polygraph examiner trying to measure subtle autonomic nervous system responses to specific questions, they create significant noise in the data.

The autonomic nervous system (ANS) — which controls the involuntary physiological processes that polygraph instruments measure — undergoes substantial changes during pregnancy. The sympathetic nervous system, responsible for the "fight or flight" response that the polygraph is designed to detect, becomes more active in some ways and less responsive in others. These changes vary across the three trimesters and between individuals, making it challenging for an examiner to predict exactly how a pregnant examinee's body will respond to testing. Research on spontaneous countermeasures in naive subjects has shown that even untrained individuals can produce responses that complicate data interpretation [3]Verified Spontaneous Countermeasures in Naive Subjects During Polygraph Testing
Found that some naive subjects make deliberate efforts to alter their responses, relevant to understanding how pregnancy-related breathing adjustments may mimic countermeasures — pregnancy adds another layer of physiological complexity on top of this.

The Three Polygraph Channels Under Stress

A modern computerised polygraph instrument simultaneously monitors at least three channels of physiological data, as outlined in our guide to analog and computerised polygraph systems:

Cardiovascular channel: Measured via a blood pressure cuff (cardio cuff) placed on the upper arm, recording relative blood pressure changes, pulse rate, and pulse amplitude.

Respiratory channel: Measured via two pneumograph tubes (one thoracic, one abdominal) placed around the chest and abdomen, recording breathing rate, depth, and pattern.

Electrodermal channel: Measured via finger plates or electrodes attached to the fingertips, recording changes in skin conductance caused by sweat gland activity.

During pregnancy, all three of these channels are affected to varying degrees by the body's normal adaptive changes. This multi-channel disruption is what makes pregnancy particularly challenging — unlike a condition that might affect only one channel (such as a respiratory infection affecting breathing patterns), pregnancy simultaneously alters the baseline for every measurement the polygraph relies on. Understanding how examiners evaluate this data is critical — our guide to understanding the polygraph chart explains the fundamentals of chart interpretation.

Blood Volume and Cardiac Output

The cardiovascular system undergoes some of the most dramatic changes during pregnancy. Plasma volume increases progressively throughout normal pregnancy, with most of this approximately 50% increase occurring by 34 weeks' gestation [4]Verified Physiological changes in pregnancy
Confirms plasma volume increases approximately 50% by 34 weeks' gestation with most increase proportional to birthweight. A systematic review and meta-analysis of longitudinal studies confirmed that plasma volume increases by approximately 6% in the first trimester, 29% by mid-second trimester, and peaks at 48% (95% CI 44-51%) in weeks 35-38 [5]Verified Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis
Confirms plasma volume increases by 6% first trimester, 29% mid-second trimester, and peaks at 48% (weeks 35-38) based on 10 longitudinal studies. This means a woman who normally has about 4 litres of blood will carry approximately 6 litres by the third trimester. This increase is necessary to supply the placenta and growing fetus with oxygen and nutrients, but it fundamentally changes the cardiovascular dynamics that the polygraph cardio cuff is designed to measure.

Cardiac output — the total volume of blood the heart pumps per minute — increases by 30-50% during pregnancy [6]Verified Physiology, Maternal Changes (StatPearls)
Confirms cardiac output increases 30-50%, tidal volume increases 30-50% due to progesterone, and diaphragm shifts up approximately 5 cm. This is achieved through a combination of increased stroke volume and increased heart rate. Heart rate increases progressively throughout pregnancy by 10 to 20 bpm, representing a 20% to 25% increase over baseline [7]Verified Cardiovascular Physiology of Pregnancy
Confirms heart rate increases progressively by 10-20 bpm representing 20-25% increase over baseline, and maternal hemodynamics largely return to nonpregnant levels by 2 weeks postpartum. Some sources report heart rate reaches and stays at 120% of baseline by 32 weeks of pregnancy [8]Verified Shock and Pregnancy: Cardiovascular Physiology
Confirms cardiac output increases 30-50%, total body water increases 6-8 litres, and heart rate reaches 120% of baseline by 32 weeks.

For the polygraph examiner, these changes mean that the cardiovascular baseline is dramatically different from what would be expected in a non-pregnant individual. The examiner relies on detecting small, stimulus-driven changes in blood pressure and pulse rate in response to specific questions. When the baseline is already elevated and variable, these small changes become much harder to detect and interpret. Understanding concepts like polygraph sensitivity and specificity becomes even more important in these challenging scenarios.

Blood Pressure Fluctuations

Blood pressure follows a distinctive pattern during pregnancy that can confound polygraph readings. During the first trimester, blood pressure often drops due to systemic vasodilation. The primary adaptive mechanism in pregnancy is a marked fall in systemic vascular resistance occurring by week six of gestation — a 35-40% decrease [7]Verified Cardiovascular Physiology of Pregnancy
Confirms heart rate increases progressively by 10-20 bpm representing 20-25% increase over baseline, and maternal hemodynamics largely return to nonpregnant levels by 2 weeks postpartum. Systolic blood pressure decreases by approximately 5-10 mmHg, and diastolic blood pressure decreases by 10-15 mmHg [9]Verified Physiology, Pregnancy (StatPearls)
Confirms systolic BP decreases 5-10 mmHg and diastolic BP decreases 10-15 mmHg with nadir at 24 weeks, and dyspnoea occurs in 60-70% of pregnant patients. This drop reaches its lowest point at approximately 24 weeks' gestation [9]Verified Physiology, Pregnancy (StatPearls)
Confirms systolic BP decreases 5-10 mmHg and diastolic BP decreases 10-15 mmHg with nadir at 24 weeks, and dyspnoea occurs in 60-70% of pregnant patients. By the third trimester, blood pressure typically returns to pre-pregnancy levels or may exceed them, particularly in women who develop pregnancy-related hypertension or preeclampsia [6]Verified Physiology, Maternal Changes (StatPearls)
Confirms cardiac output increases 30-50%, tidal volume increases 30-50% due to progesterone, and diaphragm shifts up approximately 5 cm.

This shifting blood pressure landscape creates a moving target for the polygraph examiner. The cardio cuff is calibrated at the beginning of the test to measure relative changes from a baseline. But if the baseline itself is unstable — abnormally low in the second trimester or trending upward in the late third trimester — the relative changes become unreliable indicators of deception-related autonomic arousal. This is one reason why false negatives in polygraph testing can occur under unusual physiological conditions.

Supine Hypotensive Syndrome

A particularly important consideration for polygraph testing in the third trimester is supine hypotensive syndrome, also known as inferior vena cava compression. When a pregnant person lies flat on their back, the weight of the enlarged uterus can compress the inferior vena cava (the large vein that returns blood from the lower body to the heart). This compression can cause a sudden and significant drop in blood pressure, accompanied by dizziness, nausea, and even fainting.

Even when the examinee is seated in the standard polygraph chair, the weight distribution and postural changes of late pregnancy can affect venous return and blood pressure stability, particularly during longer examinations. Gołaszewski's research in the European Polygraph specifically addressed this by recommending 10-minute breaks every 30 minutes during pregnancy examinations [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves. The study also documented modified sensor placement strategies, including placing the P1 pneumograph between the chest and abdomen, and in a second phase directly on the abdomen, to account for the physical changes of pregnancy [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves.

Mechanical Changes to Breathing

As the uterus grows, it pushes upward against the diaphragm, elevating it by approximately 4-5 centimetres by the third trimester [10]Verified Respiratory changes during pregnancy (Asthma Toolkit)
Confirms diaphragm is displaced upward by approximately 4 cm during pregnancy. This mechanical compression reduces the functional residual capacity of the lungs by about 14-27% (approximately 400-1000 mL) between the postpartum period and the third trimester [11]Verified Respiratory physiology of pregnancy: Physiology masterclass
Confirms functional residual capacity decreases 14-27% during pregnancy, subcostal angle increases from 68.5° to 103.5°, and minute ventilation increases up to 48% in first trimester. To compensate, the ribcage expands — the average subcostal angle increases from 68.5° at the beginning of pregnancy to 103.5° at term [11]Verified Respiratory physiology of pregnancy: Physiology masterclass
Confirms functional residual capacity decreases 14-27% during pregnancy, subcostal angle increases from 68.5° to 103.5°, and minute ventilation increases up to 48% in first trimester — and pregnant individuals shift from primarily diaphragmatic breathing to more thoracic (chest) breathing.

This shift is significant for the polygraph because the instrument uses two separate pneumograph tubes — one around the thorax (upper chest) and one around the abdomen — specifically to measure the relative contribution of thoracic and abdominal breathing. The pneumograph looks for changes in breathing pattern, such as suppressions (holding breath), apnoeas (pauses in breathing), and shifts in the ratio of thoracic to abdominal breathing, all of which can indicate deception-related responses. When the normal breathing pattern is already altered by mechanical compression of the diaphragm, these diagnostic indicators become less reliable.

Gołaszewski's study in the European Polygraph specifically documented how fetal movements caused visible distortions in the P1 pneumograph curve, further complicating data interpretation during pregnancy examinations [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves. The study showed "changes in the P1 pneumograph curve resulting from the child kicking in the womb" as well as "highly visible deformities of the curve from the P1 breathing sensor" [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves.

Hormonal Effects on Respiration

Beyond mechanical changes, pregnancy hormones — particularly progesterone — directly stimulate the respiratory centre in the brain. Progesterone acts as a central respiratory stimulant, increasing sensitivity of the respiratory centre to carbon dioxide [11]Verified Respiratory physiology of pregnancy: Physiology masterclass
Confirms functional residual capacity decreases 14-27% during pregnancy, subcostal angle increases from 68.5° to 103.5°, and minute ventilation increases up to 48% in first trimester. Minute ventilation starts to increase significantly — by up to 48% — during the first trimester of gestation, due to higher tidal volume with unchanged respiratory rate [11]Verified Respiratory physiology of pregnancy: Physiology masterclass
Confirms functional residual capacity decreases 14-27% during pregnancy, subcostal angle increases from 68.5° to 103.5°, and minute ventilation increases up to 48% in first trimester. The tidal volume increases by approximately 30-35% [12]Verified Pulmonary Disease and Pregnancy
Confirms tidal volume increases 30-35%, minute ventilation increases 20-40% above baseline at term, and respiratory rate remains relatively constant, while the respiratory rate itself remains relatively unchanged [12]Verified Pulmonary Disease and Pregnancy
Confirms tidal volume increases 30-35%, minute ventilation increases 20-40% above baseline at term, and respiratory rate remains relatively constant.

This increased respiratory drive creates a higher baseline of respiratory activity, making it harder for the examiner to detect the subtle breathing changes that may indicate a deceptive response. The normal "respiratory suppression" that a deceptive examinee might show in response to a relevant question may be masked by the already-increased respiratory baseline caused by progesterone stimulation. This is analogous to the challenges discussed in our article on dementia and polygraph testing, where altered neurological baselines create similar interpretation difficulties.

Dyspnoea of Pregnancy

Approximately 60-70% of pregnant individuals experience dyspnoea — a subjective sensation of breathlessness or difficulty breathing — at some point during pregnancy [9]Verified Physiology, Pregnancy (StatPearls)
Confirms systolic BP decreases 5-10 mmHg and diastolic BP decreases 10-15 mmHg with nadir at 24 weeks, and dyspnoea occurs in 60-70% of pregnant patients. This sensation is commonly reported in the third trimester [13]Verified Dyspnea in pregnancy (American Thoracic Society)
Confirms dyspnoea can occur in as many as 70% of normal pregnancies. While dyspnoea of pregnancy is not dangerous and does not indicate actual oxygen deficiency, it can cause the examinee to focus on their breathing in ways that interfere with normal polygraph data collection.

When an examinee is conscious of their breathing and actively trying to breathe "normally" or "deeply enough," this creates voluntary interference with what should be involuntary respiratory patterns. The resulting data may appear as deliberate respiratory countermeasures to the examiner, even though the examinee is simply managing a normal pregnancy symptom. Research on spontaneous countermeasures in naive subjects by Handler and Honts (1999) has demonstrated that even untrained individuals can produce countermeasure-like behaviours without intending to do so [3]Verified Spontaneous Countermeasures in Naive Subjects During Polygraph Testing
Found that some naive subjects make deliberate efforts to alter their responses, relevant to understanding how pregnancy-related breathing adjustments may mimic countermeasures — pregnancy dyspnoea adds to this risk significantly. Examiners skilled in overcoming examinee resistance must differentiate between deliberate countermeasures and normal pregnancy symptoms.

Hormonal Effects on Perspiration

The electrodermal channel — which measures changes in skin conductance caused by sweat gland activity — is also affected by pregnancy. The increased metabolic rate of pregnancy generates additional body heat. Combined with increased blood flow to the skin necessary for heat dissipation, this often results in increased baseline perspiration, particularly in the hands and fingers where the EDA sensors are attached.

Higher baseline perspiration means higher baseline skin conductance, which reduces the dynamic range available for detecting stimulus-specific responses. The EDA component of polygraph scoring relies on detecting phasic (brief, stimulus-driven) changes in skin conductance above the tonic (baseline) level. When the tonic level is already elevated, phasic responses may be smaller in relative terms, harder to distinguish from baseline fluctuations, and more easily lost in the noise of the signal.

Historical research by Kugelmass (1968) on galvanic skin response during criminal interrogation demonstrated that physiological response patterns during real interrogations differ meaningfully from laboratory-derived norms [14]Verified Experimental Evaluation of Galvanic Skin Response and Blood Pressure Change Indices During Criminal Interrogation
Found that physiological response patterns during real criminal interrogations differed meaningfully from laboratory-derived norms — a finding that becomes even more relevant when the examinee's baseline physiology is altered by pregnancy.

Temperature and Fluid Balance Effects

Pregnancy-related changes in body temperature regulation and fluid balance can also affect EDA readings. The increased blood volume and fluid retention common in pregnancy alter the electrolyte composition and hydration of the skin, which affects its electrical conductivity. These changes are not consistent across individuals or across stages of pregnancy, making it difficult for the examiner to compensate for them systematically. The total body water increases by 6-8 litres during pregnancy, with 4 litres being extracellular [8]Verified Shock and Pregnancy: Cardiovascular Physiology
Confirms cardiac output increases 30-50%, total body water increases 6-8 litres, and heart rate reaches 120% of baseline by 32 weeks, which directly impacts skin conductance measurements.

First Trimester (Weeks 1-12): Least Disruptive, Still Challenging

During the first trimester, the major cardiovascular and respiratory changes of pregnancy are just beginning. Plasma volume has only increased by approximately 6% [5]Verified Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis
Confirms plasma volume increases by 6% first trimester, 29% mid-second trimester, and peaks at 48% (weeks 35-38) based on 10 longitudinal studies, heart rate elevation is modest, and the uterus is not yet large enough to compress the diaphragm. From a purely physiological standpoint, the first trimester presents the fewest challenges for polygraph accuracy.

However, other factors complicate testing during this period. Nausea and vomiting of pregnancy affects 50-80% of all pregnant women [15]Verified ACOG Practice Bulletin No. 189: Nausea and Vomiting of Pregnancy
Confirms nausea and vomiting affects majority of pregnant women, with approximately 60% resolving by end of first trimester and 87% by 20 weeks, with symptoms typically beginning by 9-10 weeks of gestation and peaking at 11-13 weeks [16]Verified Hyperemesis Gravidarum: Practice Essentials
Confirms nausea and vomiting occurs in 50-90% of pregnancies and symptoms peak at 11-13 weeks gestation. While most cases are mild to moderate, approximately 0.3-3% of pregnancies develop hyperemesis gravidarum — the most severe form requiring medical intervention [17]Verified Hyperemesis Gravidarum (StatPearls)
Confirms hyperemesis gravidarum affects approximately 0.3 to 3% of pregnancies[18]Verified Morning Sickness: Nausea and Vomiting of Pregnancy (ACOG FAQ)
Confirms hyperemesis gravidarum occurs in up to 3 percent of pregnancies. Even mild nausea can cause physical discomfort that affects baseline physiology. Extreme fatigue is common, which can reduce autonomic responsiveness. Hormonal surges, particularly hCG and progesterone, are at their most rapid, creating physiological instability.

Some examiners may consider testing during the late first trimester if the pregnancy is uncomplicated and the examinee reports feeling well, but this is assessed on a case-by-case basis.

Second Trimester (Weeks 13-26): Moderate Risk Period

The second trimester is often called the "honeymoon period" of pregnancy because many unpleasant first-trimester symptoms resolve. Nausea typically subsides — approximately 60% of cases resolve by the end of the first trimester, and 87% resolve by 20 weeks' gestation [15]Verified ACOG Practice Bulletin No. 189: Nausea and Vomiting of Pregnancy
Confirms nausea and vomiting affects majority of pregnant women, with approximately 60% resolving by end of first trimester and 87% by 20 weeks.

However, this is also the period when significant cardiovascular changes are taking hold. Blood volume is increasing rapidly — by mid-second trimester, plasma volume has already risen 29% above pre-pregnancy levels [5]Verified Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis
Confirms plasma volume increases by 6% first trimester, 29% mid-second trimester, and peaks at 48% (weeks 35-38) based on 10 longitudinal studies. Cardiac output has risen substantially, and blood pressure may be at its lowest point due to vasodilation. Diastolic blood pressure decreases by 10-15 mmHg below pre-pregnancy levels during this period, reaching its nadir at approximately 24 weeks [9]Verified Physiology, Pregnancy (StatPearls)
Confirms systolic BP decreases 5-10 mmHg and diastolic BP decreases 10-15 mmHg with nadir at 24 weeks, and dyspnoea occurs in 60-70% of pregnant patients. Respiratory changes are beginning as the uterus grows, and the hormonal stimulation of breathing is well established. Minute ventilation has already begun its significant increase from the first trimester [11]Verified Respiratory physiology of pregnancy: Physiology masterclass
Confirms functional residual capacity decreases 14-27% during pregnancy, subcostal angle increases from 68.5° to 103.5°, and minute ventilation increases up to 48% in first trimester.

The combination of improved subjective well-being but increasing physiological deviation creates a deceptive window. The examinee may feel well enough for testing, but the examiner must recognise that the cardiovascular and respiratory baselines are already substantially altered.

Third Trimester (Weeks 27-40): Most Unsuitable for Testing

The third trimester represents the period of maximum physiological deviation from the non-pregnant state, making it the most challenging for polygraph accuracy. Plasma volume has increased by 42-48% [5]Verified Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis
Confirms plasma volume increases by 6% first trimester, 29% mid-second trimester, and peaks at 48% (weeks 35-38) based on 10 longitudinal studies, cardiac output is 30-50% above baseline [6]Verified Physiology, Maternal Changes (StatPearls)
Confirms cardiac output increases 30-50%, tidal volume increases 30-50% due to progesterone, and diaphragm shifts up approximately 5 cm, heart rate is elevated by 10-20 bpm [7]Verified Cardiovascular Physiology of Pregnancy
Confirms heart rate increases progressively by 10-20 bpm representing 20-25% increase over baseline, and maternal hemodynamics largely return to nonpregnant levels by 2 weeks postpartum, the diaphragm is displaced upward by 4-5 cm [10]Verified Respiratory changes during pregnancy (Asthma Toolkit)
Confirms diaphragm is displaced upward by approximately 4 cm during pregnancy, and functional residual capacity has decreased by up to 27% [11]Verified Respiratory physiology of pregnancy: Physiology masterclass
Confirms functional residual capacity decreases 14-27% during pregnancy, subcostal angle increases from 68.5° to 103.5°, and minute ventilation increases up to 48% in first trimester.

Physical discomfort is at its peak — back pain, pelvic pressure, and the difficulty of sitting in one position for extended periods create additional physiological noise. The risk of supine hypotensive syndrome is highest. Dyspnoea affects 60-70% of pregnant women, particularly in this trimester [13]Verified Dyspnea in pregnancy (American Thoracic Society)
Confirms dyspnoea can occur in as many as 70% of normal pregnancies. Fetal movements create visible artefacts in pneumograph recordings [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves.

Most experienced examiners will not conduct polygraph testing in the third trimester unless there are compelling legal or safety reasons that override the data quality concerns, and even then, results should be qualified and interpreted with extreme caution. For cases where testing must proceed, the accommodations described in Gołaszewski's research — including frequent breaks, modified sensor placement, and awareness of fetal movement artefacts — become essential [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves.

What the Standards Actually Say

The American Polygraph Association Standards of Practice (amended August 2024) state that the examiner should make reasonable efforts to determine that the examinee is a suitable candidate for polygraph testing [1]Verified APA Standards of Practice (Amended August 2024)
Confirms examiners should make reasonable efforts to determine suitability and consider medical conditions when conducting examinations. Basic inquiries into the medical and psychological condition of the examinee should be made where allowed by law, and mental, physical, or medical conditions that are observable by or reasonably known to the examiner should be considered when conducting and evaluating an examination [1]Verified APA Standards of Practice (Amended August 2024)
Confirms examiners should make reasonable efforts to determine suitability and consider medical conditions when conducting examinations.

The APA's Model Policy for the Evaluation of Examinee Suitability further notes that persons with some acute or chronic medical/physical conditions may be regarded as marginally suitable for polygraph testing, at which times test results should be accordingly qualified and viewed with caution [19]Verified APA Model Policy for Examinee Suitability Evaluation
Confirms examiners should determine suitability case-by-case and that persons with medical conditions may be marginally suitable with results viewed with caution. Notably, the model policy states there is no published research or theoretical rationale suggesting that any medical conditions would interfere with the polygraph test [19]Verified APA Model Policy for Examinee Suitability Evaluation
Confirms examiners should determine suitability case-by-case and that persons with medical conditions may be marginally suitable with results viewed with caution — though this is a general statement that does not specifically address the multi-channel disruption caused by pregnancy.

Donald Krapohl, a past APA President (2006) who served as Editor-in-Chief for APA publications and authored more than 100 published research papers on credibility assessment [20]Verified Fundamentals of Polygraph Practice
Confirms Donald Krapohl served as APA President (2006), Editor-in-Chief of APA publications, and authored 100+ published research papers on credibility assessment, has been instrumental in establishing evidence-based frameworks for the profession. His work on polygraph principles based on published research has helped standardise best practices across the field.

The Broader Accuracy Context

Understanding the baseline accuracy of polygraph testing provides important context for evaluating how pregnancy might affect results. The APA's 2011 Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques — published in Polygraph, 40(4), 194-305 — reviewed 38 studies involving 3,723 examinations [21]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 38 studies, 3,723 examinations, 89% accuracy for event-specific testing (CI 83-95%), 87% combined accuracy (CI 80-94%), and 11-13% inconclusive rates. The data showed that techniques intended for event-specific (single issue) diagnostic testing produced an aggregated decision accuracy of 89% (confidence interval of 83%-95%), with an estimated inconclusive rate of 11% [21]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 38 studies, 3,723 examinations, 89% accuracy for event-specific testing (CI 83-95%), 87% combined accuracy (CI 80-94%), and 11-13% inconclusive rates. The combination of all validated PDD techniques produced a decision accuracy of 87% (confidence interval 80%-94%) with an inconclusive rate of 13% [21]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 38 studies, 3,723 examinations, 89% accuracy for event-specific testing (CI 83-95%), 87% combined accuracy (CI 80-94%), and 11-13% inconclusive rates.

These accuracy figures assume examinees with normal physiological baselines. When pregnancy disrupts all three measurement channels simultaneously, the accuracy of any polygraph technique is likely to be reduced. The Empirical Scoring System (ESS), studied by Benjamin L. Blalock (2011), achieves substantial inter-rater agreement with a Fleiss kappa of.61 (95% CI:.54-.68) and mean decision agreement of 95.4% excluding inconclusive results [22]Verified Reliability of the Empirical Scoring System with expert examiners
Confirms Fleiss kappa of.61 (95% CI:.54-.68) indicated substantial inter-rater agreement, mean decision agreement reached 95.4% excluding inconclusive results — but this reliability was established under standard testing conditions, not with the altered baselines of pregnancy.

A comprehensive meta-analysis on the Comparison Question Test published in Applied Cognitive Psychology (2021) captured data from 138 datasets and found significant moderator effects, notably that level of motivation had a positive linear relationship with accuracy outcomes [23]Verified A comprehensive meta-analysis of the comparison question polygraph test
Confirms CQT can be accurate with significant moderator effects, including positive linear relationship between motivation and accuracy. This suggests that the CQT can be accurate under optimal conditions — further underscoring why maintaining those conditions matters.

The Pre-Test Assessment Process

When a pregnant examinee presents for testing, the examiner must conduct a thorough pre-test assessment. This typically includes determining the gestational age of the pregnancy, inquiring about any pregnancy-related complications or symptoms, assessing the examinee's current physical comfort level, reviewing any medications the examinee is taking, and evaluating whether the examinee can sit comfortably for the duration of the examination.

The APA suitability model policy advises that examiners should determine suitability on a case-by-case basis [19]Verified APA Model Policy for Examinee Suitability Evaluation
Confirms examiners should determine suitability case-by-case and that persons with medical conditions may be marginally suitable with results viewed with caution. This individualised approach is particularly important during pregnancy because the physiological changes vary significantly between individuals and across trimesters. Some women at 20 weeks may have minimal symptoms and relatively stable baselines, while others at the same gestational age may have significant physiological disruption.

Examiners trained in polygraph question formulation must also consider whether the emotional weight of pregnancy-related anxiety might compound physiological changes, as the psychological state of the examinee is an additional factor in data quality.

Accommodations for Pregnant Examinees

When testing proceeds, Gołaszewski's research provides a practical framework for accommodations [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves. These include ordering 10-minute breaks every 30 minutes to allow the examinee to use the bathroom (as pregnant women need to pass urine more frequently) and to reduce discomfort from prolonged sitting [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves. Sensor placement modifications may include adjusting the position of the P1 pneumograph to account for the enlarged abdomen [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves. Examiners should also be prepared to identify and account for fetal movement artefacts that may appear in the pneumograph and electrodermal recordings [2]Verified Polygraph Examination of Pregnant Women: Dilemmas and Recommendations
Demonstrates that polygraph examination of pregnant women is feasible with accommodations including 10-minute breaks every 30 minutes, modified sensor placement, and documents fetal movement artefacts in pneumograph curves.

Additional practical accommodations include ensuring the testing room is at a comfortable temperature (to minimise heat-related perspiration that could further elevate EDA baselines), providing a supportive chair that accommodates the altered posture of pregnancy, shortening the overall examination length where possible, and qualifying all results with documentation of the pregnancy and its potential effects on data quality. These considerations align with best practices for writing polygraph examination reports.

Options During the Deferral Period

When polygraph testing is deferred due to pregnancy, several alternatives may be available depending on the context. In criminal investigations, other investigative methods may be employed during the deferral period. In post-conviction sex offender monitoring (PCSOT), supervisory agencies may rely on increased reporting requirements, enhanced supervision, or other monitoring tools until polygraph testing can resume.

For employment or security screening contexts, the testing may simply be rescheduled. In some cases, a preliminary interview without physiological monitoring may be conducted to gather information that can be followed up with a full polygraph examination postpartum.

It is important to note that deferral does not mean cancellation. The examiner should schedule a specific follow-up date, typically 6-12 weeks after the expected delivery date, to ensure the examination takes place once the examinee's physiology has had sufficient time to normalise. Multivariate classifiers, which have been shown to perform as well as expert human evaluators on polygraph data [24]Verified Multivariate classifiers perform as well as experts in the detection of deception
Statistical multivariate classifiers achieved accuracy equivalent to expert human evaluators on polygraph CQT data, depend on clean baseline data — another reason deferral until optimal testing conditions can be established is the responsible choice.

Cardiovascular Recovery Timeline

Postpartum cardiovascular recovery occurs more rapidly than many expect, though the timeline varies by parameter. According to StatPearls (NIH), cardiac output rapidly declines to pre-labour values within 1-2 hours following delivery and returns to pre-pregnancy values in approximately 2 weeks postpartum [25]Verified Physiology, Postpartum Changes (StatPearls)
Confirms cardiac output rapidly declines to pre-pregnancy values in 2 weeks postpartum and SVR returns to pre-pregnant levels in 2 weeks. Systemic vascular resistance also increases to pre-pregnant levels in approximately 2 weeks postpartum [25]Verified Physiology, Postpartum Changes (StatPearls)
Confirms cardiac output rapidly declines to pre-pregnancy values in 2 weeks postpartum and SVR returns to pre-pregnant levels in 2 weeks. However, other medical sources indicate that cardiac output has fully returned to normal by 6 weeks [26]Verified Cardiovascular changes postpartum
Confirms cardiac output returns to normal by 6 weeks and normal plasma volume established by 6-8 weeks postpartum, and a McGill University anesthesia reference states that cardiac output, heart rate, and stroke volume decrease to pre-labour values 24-72 hours postpartum and return to non-pregnant levels within 6-8 weeks after delivery [27]Verified Maternal Physiological Changes During Pregnancy, Labor, and the Postpartum (McGill University)
Confirms cardiac output, heart rate, and stroke volume return to non-pregnant levels within 6-8 weeks after delivery, and blood volume slowly returns to normal over 8 weeks.

Normal plasma volume is established by 6-8 weeks postpartum [26]Verified Cardiovascular changes postpartum
Confirms cardiac output returns to normal by 6 weeks and normal plasma volume established by 6-8 weeks postpartum. Blood volume slowly returns to normal over 8 weeks [27]Verified Maternal Physiological Changes During Pregnancy, Labor, and the Postpartum (McGill University)
Confirms cardiac output, heart rate, and stroke volume return to non-pregnant levels within 6-8 weeks after delivery, and blood volume slowly returns to normal over 8 weeks. Given these varying timelines, a conservative approach of waiting at least 6-8 weeks postpartum before conducting a polygraph examination is the prudent standard.

Respiratory Recovery Timeline

Respiratory parameters also require time to normalise. By 72 hours postpartum, minute ventilation decreases halfway back to pre-pregnancy values, but remains elevated for at least 6-8 weeks after delivery [28]Verified Maternal physiology: Respiratory (OpenAnesthesia)
Confirms minute ventilation decreases halfway back to pre-pregnancy values by 72 hours postpartum but remains elevated for at least 6-8 weeks. Functional residual capacity remains below pre-pregnancy volume for 1-2 weeks [28]Verified Maternal physiology: Respiratory (OpenAnesthesia)
Confirms minute ventilation decreases halfway back to pre-pregnancy values by 72 hours postpartum but remains elevated for at least 6-8 weeks. Oxygen consumption, tidal volume, and minute ventilation all remain elevated until at least 6-8 weeks after delivery [28]Verified Maternal physiology: Respiratory (OpenAnesthesia)
Confirms minute ventilation decreases halfway back to pre-pregnancy values by 72 hours postpartum but remains elevated for at least 6-8 weeks.

The diaphragm returns to its normal position relatively quickly after delivery as the uterus involutes, but the hormonal effects on respiratory drive persist longer due to the gradual decline in progesterone levels. For the polygraph examiner, this means that respiratory baselines may not be fully normal until at least 6-8 weeks postpartum.

The Recommended Waiting Period

Based on the cardiovascular and respiratory recovery timelines, the recommended waiting period for polygraph testing after delivery is 6-12 weeks. The lower end of this range (6 weeks) corresponds to the time at which most cardiovascular parameters have returned to normal and the standard postpartum medical check-up occurs. The upper end (12 weeks) provides an additional margin for complete normalisation of all systems, particularly for women who experienced complications during pregnancy or delivery.

Additional factors that may extend the recommended waiting period include caesarean delivery (which requires additional physical recovery), postpartum depression or anxiety (which can affect autonomic responsiveness), breastfeeding (which maintains some hormonal changes), and complications such as postpartum haemorrhage or preeclampsia. The postpartum period has been described as the "fourth trimester," with the 12 weeks after delivery being an optimal time for physiological stabilisation [29]Verified Opportunities in the Postpartum Period to Reduce Cardiovascular Disease Risk (AHA Scientific Statement)
Defines the fourth trimester as the 12 weeks after delivery as optimal time for physiological stabilisation and care transitions.

Examiner Obligations and Liability

Polygraph examiners have both ethical and practical obligations when it comes to testing pregnant examinees. The APA Standards of Practice require examiners to make reasonable efforts to determine suitability and to consider known medical conditions [1]Verified APA Standards of Practice (Amended August 2024)
Confirms examiners should make reasonable efforts to determine suitability and consider medical conditions when conducting examinations. Testing a pregnant examinee without appropriate accommodations or documentation could expose the examiner to professional sanctions and liability concerns.

Examiners should document the pregnancy, the gestational age, any accommodations made, and any limitations noted in the data. If the examination proceeds, the report should clearly state that results should be interpreted with caution due to the physiological changes of pregnancy. Our guide on how to write a polygraph examination report provides a framework for this type of qualified reporting.

In legal contexts, attorneys should be aware that polygraph results obtained during pregnancy may face additional scrutiny regarding reliability. If you receive an inconclusive result during pregnancy, the physiological changes may be the reason — not any indication of deception.

Mandatory Testing Situations

In some jurisdictions and contexts, polygraph testing may be mandated — for example, in PCSOT programmes or as a condition of probation. When a mandated examinee becomes pregnant, the supervising authority and the examiner must balance the regulatory requirement for testing against the reduced reliability of results during pregnancy.

Most well-administered programmes will allow for deferral during pregnancy, with testing resuming in the postpartum period. Examiners and supervisors should document the deferral reason and establish a clear timeline for rescheduling. The goal is to ensure that when testing does occur, it produces the most reliable results possible — which benefits both the testing programme and the examinee.

Various state-level protections exist for examinees in different contexts. For example, Indiana IC 35-37-4.5 provides specific polygraph protections for victims, and similar frameworks in other states may be relevant when pregnant individuals are asked to take polygraph examinations.

How Modern Scoring Systems Handle Physiological Noise

Modern polygraph scoring systems are designed to detect deception-related physiological responses against a baseline — but they assume that baseline is relatively stable and representative of the examinee's normal physiology. The Empirical Scoring System (ESS), for instance, uses normative data to establish cutoff scores for deceptive and truthful determinations [22]Verified Reliability of the Empirical Scoring System with expert examiners
Confirms Fleiss kappa of.61 (95% CI:.54-.68) indicated substantial inter-rater agreement, mean decision agreement reached 95.4% excluding inconclusive results. When the baseline is systematically altered by pregnancy, these normative cutoffs may not apply in the same way.

Research has shown that multivariate classifiers can perform as well as expert human evaluators in detecting deception [24]Verified Multivariate classifiers perform as well as experts in the detection of deception
Statistical multivariate classifiers achieved accuracy equivalent to expert human evaluators on polygraph CQT data, but these automated systems were trained on data from non-pregnant populations. The application of standard scoring algorithms to pregnancy-altered data is an area that would benefit from further research.

Brain-based approaches to deception detection, such as the fMRI research pioneered by Langleben (2002) showing increased anterior cingulate and prefrontal cortex activation during lying [30]Verified Brain Activity During Simulated Deception: An Event-Related fMRI Study
First major fMRI deception study showing increased anterior cingulate and prefrontal cortex activation during lying, are not affected by the peripheral physiological changes of pregnancy. However, fMRI-based methods remain primarily research tools rather than practical field alternatives. As noted by Moriarty (2018), no clear standard exists for determining who is qualified to interpret neuroimaging evidence in legal settings [31]Verified Who Speaks for Neuroscience? Neuroimaging Evidence and Courtroom Expertise
Identifies that no clear standard exists for determining who is qualified to interpret neuroimaging evidence in court, further limiting these alternatives.