Wearables could revolutionise pregnancy monitoring, study finds

Common fitness trackers may help track pregnancy complications by detecting heart rate changes that mirror hormonal shifts, new research suggests.

The study found devices such as Apple Watch, Garmin and Fitbit recorded heart rate patterns that aligned with key pregnancy hormones including oestrogen, progesterone and human chorionic gonadotropin (hCG).

These hormones play vital roles in supporting a healthy pregnancy.

Researchers analysed data from more than 5,600 people using PowerMom, a bilingual digital research platform.

From this group, 108 provided continuous data covering three months before conception through six months after giving birth.

Heart rate data showed distinct trends. Early pregnancy was marked by a small dip around weeks five to nine, followed by steady rises until about two months before delivery, peaking at up to 9.4 beats per minute above baseline.

After birth, heart rates dropped below pre-pregnancy levels before stabilising at around six months.

The researchers also tracked sleep and activity patterns throughout pregnancy.

Giorgio Quer is co-senior author and director of artificial intelligence at Scripps Research.

Quer said: “Wearable devices offer a unique opportunity to develop innovative solutions that address the high number of adverse pregnancy outcomes in the US.

“Our results show that signals collected via wearable sensors follow the expected changes in hormone levels and can detect unique patterns specific to live birth pregnancies, potentially allowing the monitoring of maternal health throughout the pregnancy and postpartum.”

To check the link between sensors and hormones, the team compared wearable heart rate data with published hormonal changes from previous studies, building models that predicted how heart rate should shift as hormone levels rose or fell.

In an exploratory analysis of a small number of cases, pregnancies ending in miscarriage or stillbirth showed different heart rate patterns compared with healthy pregnancies, though researchers said larger groups are needed to confirm this.

“Hormones play a key role in pregnancy outcomes,” explained co-senior author Tolúwalàṣẹ Àjàyí, principal investigator of PowerMom.

“Discovering the association between heart rate and hormone changes could unlock new ways to predict the beginning of pregnancy or identify signs of adverse outcomes such as gestational diabetes or preeclampsia.”

Preeclampsia is a condition involving high blood pressure during pregnancy, while gestational diabetes means raised blood sugar that develops in pregnancy.

Researchers say the approach could help provide continuous oversight for high-risk pregnancies, particularly in underserved communities.

Previous work has shown that wearable devices can identify infections such as COVID-19 and other health issues by detecting changes in body patterns.

The team plans further work to examine variations across different groups, regions and socioeconomic backgrounds.

They aim to build models that flag those who might need closer monitoring.

Future studies will test whether wearable data could directly guide clinical decisions.

Researchers also plan to gather both wearable and blood test data from the same participants to validate the link between hormones and heart rate.