Influence of physical exercise during pregnancy on newborn weight: a randomized clinical trial

Introduction: Recent studies have proved that physical activity of the pregnant woman brings benefits not only for the mother but also for the fetus, given that it decreases the number of macrosomic newborns and their negative consequences in both of them. Objective: To analyze in pregnant women the influence of a moderate physical activity program in the aquatic environment on the weight of the newborn. Material and methods: A randomized clinical trial with 140 healthy pregnant women, aged between 21 and 43 years, divided into two groups, study (GE, n = 70) and control (GC, n = 70). The women were attracted at 12 weeks of gestation in the first trimester ultrasound control carried out in the different obstetrical services in Granada. They joined the program at week 20 of gestation and ended in week 37. The perinatal results were obtained from the partograph of each woman, included in the Delivery Room Services of the Complejo Hospitalario Universitario de Granada. Results: The median weight of the babies of the pregnant women who participated in the intervention was 3,250 g, compared to the babies of the control group, with a median of 3,460 g. There were statistically significant differences between the two groups (p = 0.011). Among newborns, 86.8% of both groups had weights within clinical normality, that is between 2,500 and 4,000 g. Women who followed the SWEP (Study Water Exercise Pregnant) method during pregnancy had a weight gain of 8.28 kg, compared to sedentary women, who presented a 11.17 kg weight gain. However, the rate of macrosomic infants was similar, so there were no significant differences between the two groups (GC n = 7, GE n = 6). There were no significant differences in gestation time between the two groups, with an average of 279.70 days (GC) and 280.09 days (SG) (p-value > 0.05). Conclusion: Moderate physical activity in the aquatic environment, following the SWEP methodology, does not present risks of preterm birth and does not alter the gestation time with regard to the sedentary women during pregnancy. Physical exercise has achieved a significant decrease in the weight of the newborn and a less profit ponderal during pregnancy. These two results have not been instrumental in reducing the rate of macrosomies in our study.