Low-Intensity Exercise and Pregnancy Outcomes: An Examination in the Nurses' Health Study II

Abstract

Background: The benefit of low-intensity exercise (LIE) during pregnancy is poorly understood at a time when few women participate in moderate or vigorous exercise. Using data from the Nurses' Health Study II (NHSII), we tested the hypothesis that women who engaged in more LIE before and during pregnancy experience fewer pregnancy complications. Methods: Among 116,429 U.S. female registered nurses (25–42 years of age) who were enrolled in NHSII in 1989, we included participants (36–50 years of age) who reported in 2001 or 2005 that they were pregnant and completed questionnaires about pregnancy “low-intensity exercise (yoga, stretching, toning),” and who in 2009, provided a full pregnancy outcome history. Multivariable-adjusted relative risk (RR) and 95% confidence intervals (CIs) were calculated between LIE and adverse pregnancy outcomes using log-binomial regression models. Results: Among 225 eligible pregnant participants, 71 (31.6%) reported engaging in any LIE. LIE was associated with lower preterm birth, but not significantly associated with pregnancy loss or other adverse pregnancy outcomes. The RR for any LIE for preterm birth was 0.31 (95% CI: 0.09–1.07), with a significant dose–response association [RR = 0.65 (95% CI: 0.48–0.89) per every 30-minute session]. Some suggestive inverse associations were also observed for other adverse pregnancy outcomes: the RR for any LIE for low birthweight was 0.35 (95% CI: 0.08–1.48); for preeclampsia/gestational hypertension was 0.51 (95% CI: 0.13–1.96); and for gestational diabetes was 0.64 (95% CI: 0.25–1.64). Conclusion: Pregnant women can include yoga, stretching, and toning exercise for promoting wellbeing.

Influence of Light Intensity exercise During Pregnancy on Fetal Echocardiographic and Maternal Cardiovascular Measures

“…Light intensity exercise in resistant hypertensive adults has been shown to have BP benefits after one session and benefits persist longer after the session than moderate intensity exercise [67]. Similar to our findings, light intensity stretching during pregnancy was not associated with adverse pregnancy outcomes; further, studies have found a dose-response relationship for the duration of the light intensity exercise and decreased adverse outcomes [69] and CRP [20,70]. Meta-analyses have noted exercise intensity, duration, and volume are associated with reduced risk of pregnancy complications [71].…”

“…Additionally, in rats, light intensity exercise has been shown to increase action potential amplitude, a determinant of actional potential velocity across myocardium more than moderate intensity and controls [68]. It is possible that stretching and light intensity exercise while pregnant enhance maternal cardiac autonomic control, which may reduce the risks for certain conditions, such as preeclampsia/gestational hypertension, gestational diabetes [14,17,69]. Light intensity exercise in resistant hypertensive adults has been shown to have BP benefits after one session and benefits persist longer after the session than moderate intensity exercise [67].…”

Level of Physical Activity in Pregnant Populations from Different Geographic Regions: A Systematic Review

“…Likewise, scientific studies with the adult population find that less than 10% of adults perform 150 min per week of moderate PA [ 87 ]. Specifically in pregnant women, it has been observed that, maintaining levels of light physical activity can promote wellbeing [ 88 ] as well as controlling the presence of gestational diabetes, even when starting from a lower intensity physical activity measured with accelerometry [ 89 ]. However, previous studies with direct measurements of quality accelerometry in this population are limited and the studies analyzed do not provide generalized conclusions.…”