Does Exercise During Pregnancy Affect Placental Weight?: A Randomized Clinical Trial.

Placental weight (PW) is a measure commonly used to summarize growth and aspects of placental function. In a normal pregnancy, it is reasonable to assume that PW is related to aspects of the functional capacity of the placenta. The placenta, as the site for all maternal-fetal oxygen and nutrient exchange, influences birth weight and is thus central to a successful pregnancy outcome. PW is the most common way to characterize placental growth, which relates to placental function. With physical exercise becoming an integral part of life for many women, the question of whether exercise during pregnancy has an adverse effect on the growing fetus is very important. The aim was to examine the influence of an aerobic exercise program throughout pregnancy on PW among healthy pregnant women. A randomized control trial was used (registration trial number: NCT02420288). Women were randomized into an exercise group (EG; n = 33) or a control group (CG; n = 32) that received standard care. The EG trained 3 days/week (55-60 min/session) from gestational Weeks 9-11 until Weeks 38-39. The 85 training sessions involved aerobic, muscular and pelvic floor strength, and flexibility exercises. PW and other pregnancy outcomes were measured. There was high attendance to the exercise program, and no differences in the PW at delivery were observed between study groups (CG = 493.2 ± 119.6 g vs. EG = 495.4 ± 150 g, p = .95). A regular, supervised exercise program throughout pregnancy does not affect the PW in healthy pregnant women.