Exercise in pregnant women and birth weight: a randomized controlled trial

Abstract

BackgroundBirth weight plays an important role in infant mortality and morbidity, childhood development, and adult health. To date there are contradictory results regarding the role of physical activity on birth weight. In addition, it is questioned whether exercise during second and third trimesters of pregnancy might affect gestational age and increase the risk of preterm delivery. Hence, the purpose of this study was to examine the effect of a supervised exercise-program on birth weight, gestational age at delivery and Apgar-score.MethodsSedentary, nulliparous pregnant women (N = 105), mean age 30.7 ± 4.0 years, pre-pregnancy BMI 23.8 ± 4.3 were randomized to either an exercise group (EG, n = 52) or a control group (CG, n = 53). The exercise program consisted of supervised aerobic dance and strength training for 60 minutes, twice per week for a minimum of 12 weeks, with an additional 30 minutes of self-imposed physical activity on the non-supervised week-days.ResultsThere was no statistically significant difference between groups in mean birth weight, low birth weight (< 2500 g) or macrosomia (≥ 4000 g). Per protocol analyses showed higher Apgar score (1 min) in the EG compared with the CG (p = 0.02). No difference was seen in length of gestation.ConclusionAerobic-dance exercise was not associated with reduction in birth weight, preterm birth rate or neonatal well-being.Trial RegistrationClinicalTrials.gov: NCT00617149

Physical activity in pregnancy and adverse birth outcomes

“…The Norwegian study also showed a protective effect (OR = 0.82; 95%CI: 0.73-0.91) against prematurity in women that exercised 3 to 5 times a week. The results also agree with a randomized study of 105 sedentary primiparous pregnant women (mean age: 30.7 ± 4.0 years and pregestational body mass index (BMI): 23.8 ± 4.3), which concluded that aerobic and resistance exercises are not associated with preterm birth 26 . It should be noted that the women in the study were sedentary and therefore had no previous physical conditioning.…”

The Effect of Supervised Prenatal Exercise on Fetal Growth

“…Exercise intensity was assessed by heart rate monitors 19,20,[23][24][25][26][27][28][29][32][33][34][35][36]40,41,[43][44][45]47 and the Borg Scale of Perceived Exertion. 17,37,[42][43][44][45][46] Three studies did not report exercise intensity 31,38,39 and many did not give a precise intensity range (eg, less than 70% heart rate reserve). A summary of study characteristics is provided in Appendix 3 (available online at http://links.lww.com/AOG/A626).…”

“…Thirteen trials had an exclusively aerobic intervention 19,20,23-33 and 14 combined aerobic and resistance training. 17,[34][35][36][37][38][39][40][41][42][43][44][45][46] Only one study examined the effects of resistance exercise alone. 47 The frequency of the prescribed exercise ranged from one to five times per week.…”

The Effect of Swimming During Pregnancy on Fetal Growth

“…Although moderate levels of physical activity are typically recommended for expectant mothers to help maintain healthy pregnancies and for the mother's long-term health (Wang and Apgar 1998), the epidemiological evidence is mixed on whether physical activity is advantageous to developing fetuses (Hatch et al 1993;Morris and Johnson 2005;Sternfeld et al 1995;Chasan-Taber et al 2007;Kramer and McDonald 2006;Haakstad and Bø 2011;Hopkins et al 2010;Jukic et al 2011). Few studies have examined the potential benefit of recreational activities such as swimming during pregnancy, though a number of studies have focused on the potential risk of adverse pregnancy outcomes from exposure to waterborne contaminants (e.g., disinfection byproducts).…”