Our sources
The Science of Bloom
Last updated: August 17, 2026
Bloom is a wellness product built on a simple idea: your own health data, read in the context of your pregnancy. It doesn't diagnose, treat, or replace your care team — it helps you understand your trends and prepare for the conversations that matter.
Medical review
Every piece of educational content in Bloom is reviewed before you see it by Jaimie Maines, MD, FACOG — board-certified Obstetrician/Gynecologist and board-certified Maternal Fetal Medicine specialist. Content is grounded in guidance from the American College of Obstetricians and Gynecologists (ACOG), Williams Obstetrics, and peer-reviewed literature.
How Bloom calculates your ranges
Your adjusted ranges start with your own baseline — the pre-pregnancy history your devices already recorded. Bloom then applies trimester-based adjustments reflecting well-documented changes of pregnancy, like the natural rise in resting heart rate as blood volume expands.
Until your history connects, Bloom shows an estimate based on age-based reference values, which personalizes once your own data is available.
Ranges are observational context, not medical thresholds: a reading outside your range is a prompt to mention something to your care team — never a diagnosis.
References
Wearable & biometric research in pregnancy
- Apple Women's Health Study (AWHS), 2024 — 757 pregnancies, Apple Watch data (Mishra et al., Am J Obstet Gynecol Glob Rep).
- Oura Ring Pregnancy Study, 2025 — 10,318 pregnancies, Oura Ring Gen3 (JMIR mHealth uHealth).
- WHOOP/WVU Study, 2022 — 18 active women, continuous WHOOP monitoring (Rowan et al., BMC Pregnancy Childbirth).
- University of Turku Study, 2022 — 58 women, Samsung Gear Sport smartwatch (Azimi et al., JMIR mHealth uHealth).
- Wearable sensor bracelet study, 2023 — 23 women, Ava Fertility Tracker (PMC).
Heart rate & circulation
- Green et al., 2020 — 1,041 women, gestation-specific vital sign reference ranges in pregnancy (Obstet Gynecol).
- Sanghavi M, Rutherford JD. Cardiovascular Physiology of Pregnancy. Circulation. 2014;130:1003–1008.
- Cunningham FG, et al. Williams Obstetrics, 26th ed. McGraw Hill; 2022. Chapter 4: Maternal Physiology.
Heart rate variability & circadian rhythm
- Circadian rhythm HR/HRV study, 2025 — smartwatch PPG data across pregnancy (npj Women's Health).
- Cunningham FG, et al. Williams Obstetrics, 26th ed. McGraw Hill; 2022. Chapter 4: Maternal Physiology (autonomic adaptation).
Sleep
- Fitbit/Google Sleep Study, 2024 — 11,470 pregnant users, 13,457 new parents (SLEEP).
- Hirshkowitz M, et al. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1:40–43.
- Pien GW, Schwab RJ. Sleep Disorders During Pregnancy. Sleep. 2004;27:1405–1417.
Weight & nutrition
- Institute of Medicine. Weight Gain During Pregnancy: Reexamining the Guidelines. National Academies Press; 2009.
- American College of Obstetricians and Gynecologists. Nutrition During Pregnancy (patient education: prenatal vitamins and folic acid).
- American College of Obstetricians and Gynecologists. Weight Gain During Pregnancy. ACOG Committee Opinion No. 548 (reaffirmed).
Blood pressure & hypertensive disorders
- American College of Obstetricians and Gynecologists. Gestational Hypertension and Preeclampsia. ACOG Practice Bulletin No. 222 (2020 lineage).
- International Society for the Study of Hypertension in Pregnancy (ISSHP), 2021 classification and management recommendations.
Weekly development
- American College of Obstetricians and Gynecologists. Your Pregnancy and Childbirth: Month to Month, 7th ed.
- Cunningham FG, et al. Williams Obstetrics, 26th ed. McGraw Hill; 2022.
- Perinatology.com: Fetal Development reference.
- Cleveland Clinic: Fetal Development — Stages of Growth.
- Mayo Clinic: Pregnancy week by week.
Questions about our sources or methodology? support@bloomformoms.com