Despite immense research highlighting maternal-fetal benefits of exercise during pregnancy, there remain concerns that exercise may undermine placental function. Although maternal exercise has demonstrated favorable aerobic conditioning responses in the mother, it is not known whether maternal exercise promotes increased angiogenesis in the placenta, perhaps at the expense of impaired endoplasmic reticulum (ER) homeostasis and/or oxidative stress. We investigated if a mild (30% heart rate reserve [HRR]) and/or moderate (70% HRR) exercise regime in healthy pregnant women impacted placental markers of angiogenesis, ER stress, and oxidative stress. We hypothesized that the improved aerobic conditioning of mothers who exercise is beneficial to enhance placental angiogenesis and normal maternal-fetal outcomes.
Placental tissues were collected within 1 hour of delivery from a convenience sample of 29 healthy mothers of full-term infants. Twenty-one women participated in routine exercise from mid-gestation (16-20 weeks) until term of either mild or moderate intensity, while 8 sedentary women served as controls.
No differences were identified between groups including gestational length, fetal-placental weight ratio, or APGAR scoring. All exercisers exhibited a significant 20-fold increase in the mRNA (as assessed by quantitative real-time PCR) and a 10-fold increase in the protein expression of angiogenin (e.g. ANG1) in the placenta. However, in both exercising groups no increases in placental markers (i.e. HIF1α, VEGF), ER stress (i.e. spliced XBP1, ATF4, ATF6, CHOP, and BAX), or oxidative stress (i.e. SOD1, SOD2) were observed.
Overall, our study suggests that mild and moderate intensity exercise increases angiogenesis, but does not increase placental oxidative or ER stress in healthy pregnancies, bolstering support for routine exercise as a part of standard care in pregnant women. Future studies are warranted to investigate the potential benefits of exercise on ANG1 in pathological pregnancies.

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