Is it safe to exercise during pregnancy? What the evidence says

For most women, the answer is yes — and the evidence goes further, suggesting activity is not merely permissible but actively helpful. The caveat matters, though: "most women" means those without obstetric or medical complications, and pregnancy is exactly the situation where a personalised sign-off from your own maternity team counts more than a general rule.

The clearest statement comes from the American College of Obstetricians and Gynecologists, which advises that clinicians "should encourage their patients to continue or to commence exercise as an important component of optimal health" [s1]. Its committee opinion concludes that "physical activity and exercise in pregnancy are associated with minimal risks and have been shown to benefit most women," and that "in the absence of obstetric or medical complications or contraindications, physical activity in pregnancy is safe and desirable" [s1]. Women who were already doing vigorous aerobic activity, or who were physically active before pregnancy, can continue during pregnancy and the postpartum period [s1].

What exercise appears to do

ACOG links exercise in pregnancy to a set of concrete benefits drawn from observational studies: "decreased gestational diabetes mellitus, cesarean birth and operative vaginal delivery, and postpartum recovery time," as well as a role in preventing depressive disorders after birth [s1].

The strongest quantitative evidence sits in a large systematic review and meta-analysis in the British Journal of Sports Medicine, which pooled 106 studies covering 273,182 women [s2]. Using moderate- to high-quality evidence from randomised trials, it found that exercise-only interventions reduced the odds of gestational diabetes (odds ratio 0.62, 95% CI 0.52–0.75), gestational hypertension (OR 0.61, 95% CI 0.43–0.85) and pre-eclampsia (OR 0.59, 95% CI 0.37–0.90) compared with no exercise [s2]. Notably, exercise combined with other interventions such as diet did not show the same effect — it was the exercise-only comparisons that moved the numbers [s2].

How much, and how hard

The same review put a rough dose on it. To achieve at least a 25% reduction in the odds of developing gestational diabetes, pre-eclampsia and gestational hypertension, "pregnant women need to accumulate at least 600 MET-min/week of moderate-intensity exercise," which the authors illustrate as about "140 min of brisk walking, water aerobics, stationary cycling or resistance training" [s2]. That is a research metric rather than a prescription, but it maps closely onto everyday advice: the NHS suggests trying "to keep active on a daily basis," noting that "30 minutes of walking each day can be enough" [s3].

Intensity is where common sense and evidence meet. The NHS recommends the "talk test": "you should be able to hold a conversation as you exercise when pregnant. If you become breathless as you talk, then you're probably exercising too strenuously" [s3]. It is also blunt about reassurance many women want: "Exercise is not dangerous for your baby. There is evidence that active women are less likely to experience problems in later pregnancy and labour" [s3]. The counterweight is equally plain — "do not exhaust yourself," and expect to slow down as pregnancy progresses [s3].

The limits and the red flags

Two honest limits apply. First, much of ACOG's benefit list comes from observational studies, which can be confounded by the fact that healthier women exercise more [s1]. The trial-based meta-analysis is more robust, but even there the effect is on odds, not certainties [s2]. Second, none of this overrides an individual clinical picture: the guidance is explicitly conditional on the absence of complications or contraindications [s1].

That is why the framing throughout is talk to your own team. The guidance is explicit that its "safe and desirable" verdict applies "in the absence of obstetric or medical complications or contraindications," and that some modifications may be needed for the normal anatomical and physiological changes of pregnancy [s1]. A range of medical and obstetric conditions can change that calculus, and only a clinician who knows your pregnancy can weigh them [s1]. The NHS advice is the practical rule: keep active, use the talk test, "do not exhaust yourself," and "if in doubt, consult your maternity team" [s3]. Stop and seek advice if exercise brings on symptoms such as bleeding, pain or dizziness. This article is informational and is not a substitute for that personalised advice.

Sources

• Physical Activity and Exercise During Pregnancy and the Postpartum Period (Committee Opinion No. 804) — Obstetrics & Gynecology (American College of Obstetricians and Gynecologists), 2020-04-01
• Prenatal exercise for the prevention of gestational diabetes mellitus and hypertensive disorders of pregnancy: a systematic review and meta-analysis — British Journal of Sports Medicine, 2018-10-18
• Exercise in pregnancy — NHS, 2023-01-01