Fitness, DASH Diet, and Preeclampsia Risk: What We Know

Regular exercise during pregnancy is a sensible way to support health, and better cardiorespiratory fitness tracks with lower risk of hypertensive disorders of pregnancy. That association deserves attention. It does not yet prove that increasing fitness prevents preeclampsia.

The distinction matters because preeclampsia can threaten both parent and fetus, while lifestyle advice often outruns the studies behind it. Fitness has the stronger evidence base: a systematic review and meta-analysis found that lower cardiorespiratory fitness was associated with greater risk of hypertensive disorders of pregnancy. DASH-style eating has a reasonable cardiovascular rationale and encouraging observational data, but pregnancy trials have not shown that it prevents preeclampsia.

Fitness predicts risk, but has not yet passed the prevention test

A 2022 systematic review and meta-analysis by Al-Huda et al. reviewed 10 studies of cardiorespiratory fitness and hypertensive disorders of pregnancy; five studies could be pooled quantitatively. Across those pooled studies, lower fitness was associated with higher risk.

That is the best direct evidence in this comparison, but it has important wrinkles. The studies did not measure fitness the same way. Some used VO2peak, estimated VO2max, oxygen uptake at anaerobic threshold, or work rate. Some used direct cardiopulmonary exercise testing, while others estimated VO2max with field tests. Field estimates tend to underestimate true fitness, which adds measurement error and makes studies harder to compare.

The meta-analysis also could not separately analyze body mass index, pre-existing hypertension, or gestational weight gain because too few studies were available. Those factors matter: low fitness often travels with insulin resistance, inflammation, and higher body weight, all of which can raise hypertensive-pregnancy risk. Fitness may contribute independently, may partly reflect metabolic health, or both. The current evidence cannot cleanly sort that out.

Reverse causation is another live possibility. A pregnancy already developing complications can limit activity and cause deconditioning, making low fitness partly a consequence rather than a cause. A separate 2025 systematic review by Pei et al. found that more sedentary behavior during pregnancy was associated with greater risk of preeclampsia and/or gestational hypertension. It points in the same direction, but it relies on observational evidence and shares the same direction-of-causation problem.

So the honest reading is useful but narrow: fitness and activity patterns identify a lower-risk profile. They do not yet give us a verified fitness threshold or a guaranteed reduction in preeclampsia risk.

Can fitness improve during pregnancy?

Yes. An eight-week randomized trial of online supervised high-intensity interval training in pregnant participants found improvements in fitness measures related to anaerobic threshold, with no adverse pregnancy outcomes reported. The intervention did not measure hypertensive disorders of pregnancy as an endpoint, so it showed that fitness can change during pregnancy, not that those changes prevent preeclampsia. Read the trial here.

A 2025 retrospective cohort study of people who continued CrossFit during pregnancy likewise found no significant increase in obstetric complications. That offers some real-world reassurance for high-intensity functional training among participants already inclined and able to do it. It does not establish safety for every pregnancy, especially for people with low baseline fitness, medical complications, or contraindications to exercise.

High-intensity training is not the only route to better aerobic capacity. In non-pregnant working-age adults, a 2026 meta-analysis of low-intensity endurance training found that training below the first lactate or ventilatory threshold improved aerobic fitness. That supports a practical point: pregnancy exercise does not need to resemble a reality-show final challenge. The pregnancy-specific question is not whether higher intensity can work; it is what form of training is appropriate for an individual pregnancy.

DASH eating has a weaker preeclampsia case

DASH emphasizes fruits, vegetables, whole grains, legumes, nuts, and lower-fat dairy while limiting foods high in sodium, saturated fat, and added sugar. Its track record for blood pressure outside pregnancy makes it an appealing prenatal pattern. The pregnancy evidence, however, has an endpoint problem.

A 2026 systematic review and meta-analysis of DASH and gestational hypertension reported an association between greater DASH adherence and lower risk of gestational hypertension. The review describes plausible pathways involving nitric oxide bioavailability, endothelin-1, and the VEGF/sFlt-1 angiogenic axis.

Gestational hypertension and preeclampsia overlap, but they are not interchangeable diagnoses. Gestational hypertension is new-onset high blood pressure after 20 weeks of pregnancy. Preeclampsia involves a broader syndrome that can include proteinuria, organ dysfunction, and characteristic angiogenic imbalance. A result for gestational hypertension cannot be relabeled as proof of preeclampsia prevention.

A prospective longitudinal study by Li et al. examined AHEI, Mediterranean-style, and DASH adherence in relation to pregnancy complications, including preeclampsia. It strengthens the observational case for healthier dietary patterns, but the published abstract does not provide enough detail here to state a precise preeclampsia effect estimate, confidence interval, or adjustment model.

More fundamentally, dietary-adherence studies face healthy-user bias. People who score highly on DASH patterns may also have more consistent prenatal care, different baseline health, more resources, and lower chronic stress. Statistical adjustment can help, but it cannot guarantee that diet itself caused the difference. No pregnancy-specific randomized controlled trial in this evidence base tested a DASH intervention with preeclampsia incidence as a primary or secondary endpoint.

Genes shape susceptibility; they do not settle the outcome

Preeclampsia involves impaired placental development, placental ischemia, and endothelial dysfunction. The sFlt-1/PlGF pathway is central to that biology: higher sFlt-1 and lower PlGF can disrupt angiogenic signaling. Individual susceptibility has partly constitutional and genetic roots, which helps explain why similar lifestyles can yield different pregnancies.

Still, neither the fitness nor DASH studies measured sFlt-1/PlGF as the mediator linking the lifestyle exposure to hypertensive disorders. The proposed mechanism is biologically plausible, not demonstrated mechanistic proof in pregnant humans. No genetics-specific intervention or genome-wide association study establishes how to personalize exercise or DASH advice for preeclampsia prevention.

What to do with this evidence

For uncomplicated pregnancies, regular, clinician-cleared physical activity remains a reasonable health practice. The fitness evidence is consistent, and structured exercise can improve fitness during pregnancy. Yet no available trial has shown that raising cardiorespiratory fitness lowers preeclampsia incidence.

DASH-pattern eating is also a sound dietary default for general cardiometabolic health. It should not be marketed as a proven preeclampsia-prevention treatment. The available evidence supports an association with lower hypertensive-pregnancy risk, with stronger evidence for gestational hypertension than for preeclampsia itself.

Better fitness is the better-supported lifestyle signal. DASH eating is sensible, but its preeclampsia claim remains observational. Neither replaces prenatal monitoring or individualized medical advice for people at elevated risk.

For anyone with prior preeclampsia, chronic hypertension, kidney disease, diabetes, multiple gestation, concerning symptoms, or exercise restrictions, the next step is a prenatal clinician—not an attempt to out-train placental biology.