Evidence-Based Exercise in Pregnancy and Postpartum | Dr Margie Davenport

What It Covers

Exercise physiologist Margie Davenport, who chaired the 2019 Canadian pregnancy exercise guidelines and the 2025 International Olympic Committee consensus statement, presents randomized controlled trial evidence showing that exercise during pregnancy reduces gestational diabetes, preeclampsia, and prenatal depression by 40–67%, while dismantling decades of myths around heart rate limits, heavy lifting, and fetal safety.

Key Questions Answered

• •The 140 BPM myth: The 1985 ACOG guideline introduced a 140 beats-per-minute heart rate ceiling as a placeholder, never intended as a permanent limit. No evidence supports it, yet it persists in clinical practice and was reintroduced in a recent ACOG table, causing widespread unnecessary restriction. Pregnant women should instead use the "talk test" — able to speak but not sing — or age-adjusted heart rate reserve zones to gauge moderate intensity.
• •40–67% risk reduction from exercise: Synthesizing hundreds of randomized controlled trials for the 2019 Canadian guideline, Davenport's team found that 150 minutes of moderate-intensity activity per week reduces preeclampsia and gestational diabetes risk by roughly 40%, and cuts prenatal depression odds by 67%. Even 10 minutes of brisk walking daily produces a 25% reduction in preeclampsia risk, making any movement meaningfully protective.
• •Heavy lifting safety: A survey of nearly 700 women who continued lifting above 80% of one-rep maximum during pregnancy showed a 51% reduction in pregnancy complications compared to those who followed guidelines and stopped. Davenport's lab has since completed acute trials using back squats, bench press, and deadlifts at 90% of 10-rep maximum, finding fetal heart rate and blood flow well maintained throughout.
• •Maintaining fitness protects postpartum recovery: Women who sustain training volume and sports-specific skills throughout pregnancy show reduced injury risk after delivery. Reducing activity during pregnancy — often advised out of caution — appears to increase postpartum injury vulnerability. Earlier postpartum loading, rather than waiting six weeks, supports faster healing and better mental health outcomes, with a 45% reduction in postpartum depression odds linked to resuming activity promptly.
• •High-intensity interval training is well tolerated: Davenport's team tested 10 one-minute bouts at 90% maximal effort in pregnant women, directly measuring fetal heart rate and uterine blood flow. Both remained well maintained throughout. This was the first controlled study of HIIT in pregnancy, and the data has since informed a shift away from blanket intensity caps toward individualized, athlete-centered shared decision making.
• •Fueling matters for fertility and pregnancy: Low energy availability — where caloric intake fails to match training expenditure — increases miscarriage risk and contributes to infertility in athletes. Exercise alone does not impair fertility; inadequate fueling relative to output does. Women trying to conceive while training should prioritize energy balance, as the body requires sufficient available energy to sustain implantation and early fetal development.
• •Postpartum sleep quality improves with exercise: Randomized controlled trials show physical activity in the postpartum period does not increase total sleep duration or reduce nighttime awakenings, but measurably improves sleep quality. Higher sleep quality independently associates with lower postpartum depression rates, creating a compounding benefit. Most postpartum exercise research focuses on walking; resistance training data remains scarce and represents a significant evidence gap.