Pregnancy turns blood pressure into something you actually worry about. Outside of pregnancy, a reading of 135/85 might get a note in your chart and a suggestion to cut back on salt. During pregnancy, that same number could signal the early stages of preeclampsia, a condition that kills an estimated 76,000 women and 500,000 infants worldwide every year. The difference between a normal pregnancy and a dangerous one sometimes comes down to a few millimeters of mercury measured at the right time.
The problem is timing. Most prenatal care schedules involve clinic visits every four weeks during the second trimester and every two weeks in the third. Blood pressure gets checked at each visit. But preeclampsia can develop between appointments, and by the time a woman shows up for her next scheduled check, a manageable situation may have become an emergency. Home monitoring with a traditional cuff is the obvious solution, but a surprising number of women find the process uncomfortable and stop doing it consistently.
This is where camera-based contactless monitoring enters the picture. Point a smartphone camera at your face for 30 seconds, and rPPG algorithms attempt to extract cardiovascular signals from subtle skin color changes caused by blood flow. No cuff, no wires, no equipment beyond the phone already in your hand. The question isn't whether the concept is appealing. It obviously is. The question is whether the measurements are trustworthy enough to matter.
"Home monitoring can enhance the early detection and management of pregnancy-related hypertension, while also empowering women to take an active role in their own health care." — Andersson et al., JMIR Human Factors (2026)
Camera-based blood pressure monitoring in pregnancy
The most substantial study on contactless blood pressure measurement in pregnant women was published in January 2026 by Andersson et al. at Lund University and Skane University Hospital in Sweden. Their prospective longitudinal study, published in JMIR Human Factors, evaluated the Anura smartphone app across three distinct groups: 132 women with normotensive pregnancies, 40 with high-risk pregnancies, and 87 women diagnosed with preeclampsia.
The Anura app uses transdermal optical imaging (TOI), a technology related to rPPG that captures blood flow patterns through a 30-second facial scan using the phone's front camera. The study collected 4,932 blood pressure measurements with Anura, of which 539 had corresponding manual cuff measurements for comparison.
The results split cleanly along risk lines. In normotensive pregnancies, Anura consistently showed diastolic values about 5-7 mmHg higher and systolic values slightly lower than manual readings. Those differences held through the second and third trimesters with reasonable consistency. For routine tracking of blood pressure trends in uncomplicated pregnancies, this level of accuracy could be useful as a screening layer between clinic visits.
In high-risk pregnancies, both systolic and diastolic readings from the app ran lower than manual measurements, particularly in the second and third trimesters. For women with preeclampsia, the gaps widened further. Bland-Altman analysis showed increasing variability and wider limits of agreement as clinical severity increased. Put plainly: the app underestimated blood pressure in the patients where accurate measurement matters most.
This isn't a reason to dismiss the technology. It's a reason to be clear-eyed about where it works today and where it doesn't yet.
Comparing maternal blood pressure monitoring methods
| Method | Contact required | Comfort level | Accuracy in normotensive pregnancy | Accuracy in preeclampsia | Daily home use | Cost to patient | Validated for pregnancy |
|---|---|---|---|---|---|---|---|
| Manual cuff (clinic) | Yes, arm cuff | Moderate | Gold standard | Gold standard | Not practical | Free at visits | Yes |
| Automated oscillometric (home) | Yes, arm cuff | Low to moderate | Good, may read lower than clinic | Good with validated device | Possible but compliance drops | $40-80 device | Some devices validated |
| Smartphone camera (Anura) | None, facial scan | High | Acceptable (±5-7 mmHg diastolic offset) | Poor, underestimates values | Easy, 30 seconds | Free app | Under investigation |
| Wrist-based wearable | Yes, wrist sensor | Moderate | Variable, position-dependent | Limited data | Possible | $50-300 device | Few pregnancy-specific studies |
| Finger-based PPG device | Yes, finger clip | Low to moderate | Emerging research | Limited data | Possible | $30-100 device | Not validated for pregnancy |
Sources: Andersson et al. (2026), Tucker et al. (2017), Bello et al. (2018).
The table illustrates the core trade-off. The most comfortable and accessible method (smartphone camera) is the least accurate in the population where accuracy matters most. The most accurate methods require equipment that many women find inconvenient enough to skip.
Remote monitoring and preeclampsia detection
Beyond the accuracy question, there's a separate line of research asking whether remote monitoring of any kind changes outcomes. A 2025 retrospective study from George Washington University evaluated the Babyscripts digital health platform across 823 pregnant patients at a university-based obstetric practice. The study, published in the Journal of Perinatal Education, tracked engagement with remote monitoring tools that allowed patients to submit weight and blood pressure data from home.
The demographics of the study population are worth noting: nearly one-third of patients identified as Black, and 32% were Medicaid or Medicare recipients. Living in economically distressed communities and having a prior full-term pregnancy were both associated with lower engagement. First-time mothers and older patients tended to engage more.
The study found a nonsignificant trend suggesting that higher engagement with remote monitoring was associated with increased preeclampsia detection. That's a carefully hedged finding, but it points in an interesting direction. Preeclampsia doesn't always announce itself with obvious symptoms. Some women develop dangerously high blood pressure without headaches, visual changes, or swelling. If the only time their blood pressure gets checked is at a scheduled clinic visit, the window for early intervention narrows.
A separate systematic review published in BMJ Open in 2025 examined qualitative studies across eight countries on remote blood pressure monitoring during pregnancy. The review found that women generally valued the sense of control and reassurance that home monitoring provided, but noted persistent barriers around digital literacy, device access, and the anxiety that self-monitoring can sometimes create when readings are ambiguous.
Clinical applications in maternal care
Prenatal screening between visits
The most straightforward application is filling the gaps between prenatal appointments. A woman in her third trimester might see her provider every two weeks. That leaves 13 days where blood pressure changes go unobserved. A daily 30-second facial scan on a smartphone could flag upward trends that warrant an earlier visit, even if the absolute values aren't precise enough for diagnosis.
This screening model doesn't require the camera-based measurement to be as accurate as a clinical-grade device. It needs to reliably detect meaningful changes over time. Trend detection has a lower accuracy bar than point-in-time diagnosis, and it's where smartphone-based systems may prove useful first.
Postpartum monitoring
Postpartum preeclampsia can develop up to six weeks after delivery, and many women have minimal contact with the healthcare system during that period. The standard postpartum visit happens at six weeks, which leaves a long window of vulnerability. Remote monitoring could catch blood pressure spikes during the early postpartum period when clinic visits are infrequent and women are focused on newborn care rather than their own symptoms.
Research from the University of Pennsylvania found that remote blood pressure monitoring after delivery reduced poor maternal outcomes in populations with hypertensive disorders during pregnancy. The program specifically targeted the postpartum period, when follow-up compliance tends to drop and complications can develop silently.
Health equity considerations
Maternal mortality in the United States remains disproportionately high among Black women, who experience preeclampsia at higher rates and face documented barriers to accessing consistent prenatal care. A monitoring tool that requires nothing beyond a smartphone could reduce one barrier, though it can't address the systemic factors that drive disparities in care quality.
The Patchen et al. (2024) protocol from MedStar Health specifically designed a remote blood pressure monitoring program adapted for Black women and birthing persons, recognizing that technology alone doesn't solve access problems if it isn't designed with the affected populations in mind. Their protocol, published in the International Journal of Environmental Research and Public Health, lays out a framework for evaluating whether remote monitoring can improve outcomes in populations that bear the heaviest burden of maternal morbidity.
Current research and evidence gaps
The maternal rPPG field has several problems to work through before camera-based monitoring becomes clinically viable for pregnancy.
Accuracy in hypertensive states is the central challenge. The Andersson et al. (2026) study showed that the Anura app's agreement with manual measurements deteriorated as blood pressure increased. Since the whole point of monitoring during pregnancy is to catch hypertension, a system that underestimates high readings has an obvious problem. The physiological changes of pregnancy, including increased blood volume, altered vascular resistance, and edema, affect the optical signals that rPPG systems rely on, and current algorithms haven't been trained specifically to account for these changes.
Skin tone validation remains incomplete. Melanin affects how light interacts with skin, which influences rPPG signal quality. Most maternal rPPG studies have been conducted in populations with limited skin tone diversity. Given that preeclampsia disproportionately affects Black women, validating camera-based systems across the full range of skin tones isn't just good science. It's an equity requirement.
Longitudinal accuracy over pregnancy hasn't been established. Blood pressure, blood volume, cardiac output, and skin perfusion all change substantially across trimesters. An algorithm that performs well in the first trimester may drift as pregnancy progresses. The Andersson study captured measurements across trimesters but noted varying levels of agreement at different gestational stages.
Regulatory pathways for pregnancy-specific contactless monitoring don't exist yet. No camera-based blood pressure system has received FDA or CE clearance specifically for use in pregnant populations. The Anura app has regulatory standing for general adult use in some markets, but pregnancy-specific clearance would require dedicated clinical evidence.
Where maternal contactless monitoring goes from here
The path forward probably looks like incremental adoption rather than a single breakthrough. Smartphone-based blood pressure screening in low-risk pregnancies is the nearest-term application. The accuracy isn't clinical-grade, but it doesn't need to be if the goal is detecting trends rather than making diagnoses. A system that reliably says "your blood pressure appears to be rising, call your provider" would be valuable even with a 5-7 mmHg margin of error.
High-risk and preeclamptic pregnancies will take longer. The algorithms need pregnancy-specific training data, diverse skin tone representation, and validation against the hemodynamic changes that occur as pregnancy progresses. The Andersson study is a starting point, not an endpoint.
Circadify has developed contactless vital sign measurement technology using rPPG and is working to extend these capabilities into maternal health applications. The company's camera-based platform extracts heart rate, respiratory rate, and other physiological signals without physical contact, an approach that aligns with the growing demand for accessible, low-friction prenatal monitoring tools.
The broader shift toward remote maternal care accelerated during the pandemic and hasn't reversed. Telehealth prenatal visits are now routine in many health systems. Adding contactless vital sign measurement to those virtual encounters would close the gap between seeing a patient on screen and actually assessing their cardiovascular status. That's the goal. Getting the accuracy right is the work that remains.
Frequently asked questions
Can a smartphone camera measure blood pressure during pregnancy?
Early research shows promise but with limitations. The Anura smartphone app, tested on 259 pregnant women at Lund University, showed acceptable agreement with manual cuff measurements in normotensive pregnancies. However, accuracy decreased in high-risk pregnancies and women with preeclampsia, where the app consistently underestimated both systolic and diastolic values. The technology is not yet reliable enough for clinical decision-making in complicated pregnancies.
How could contactless monitoring help detect preeclampsia earlier?
Preeclampsia affects 3-8% of pregnancies and is diagnosed partly through blood pressure changes. A smartphone-based monitoring tool that pregnant women could use daily at home would capture BP trends between clinic visits, potentially catching hypertensive episodes that develop in the weeks between scheduled appointments. A George Washington University study of 823 patients found a trend linking higher engagement with remote monitoring to increased preeclampsia detection, though the result did not reach statistical significance.
Is camera-based blood pressure monitoring accurate enough for pregnant women?
Not yet for all populations. In normotensive pregnancies, the Anura app showed diastolic readings approximately 5-7 mmHg higher and systolic readings slightly lower than manual cuff measurements. In preeclamptic pregnancies, the differences were larger and clinically concerning, with the app underestimating blood pressure. Further algorithm development is needed before the technology can be recommended for high-risk maternal populations.
What vital signs can cameras measure in pregnant women?
Current rPPG technology can extract heart rate from facial video with reasonable accuracy across populations. Blood pressure estimation from camera-based systems is less mature but under active investigation for maternal use. Respiratory rate and oxygen saturation measurement via camera remain less reliable and have not been specifically validated in pregnant populations.