Exercise training in pregnancy reduces offspring size without changes in maternal insulin sensitivity

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Exercise Physiology

Background:

• The in utero environment is critical for healthy infant development.
• Maternal insulin sensitivity reduction in pregnancy significantly impacts fetal growth.
• Aerobic exercise may influence fetal growth by modulating maternal insulin sensitivity and nutrient supply.

Purpose of the Study:

• To investigate the impact of aerobic exercise in the latter half of pregnancy on maternal insulin sensitivity.
• To assess the effects of exercise on neonatal outcomes, including birth weight and body composition.
• To examine the relationship between maternal insulin sensitivity, exercise, and fetal growth markers.

Main Methods:

• A community-based, randomized controlled trial involving 84 healthy nulliparous women.
• Participants engaged in a home-based stationary cycling program from 20 weeks gestation until delivery.
• Maternal insulin sensitivity, neonatal auxology, body composition, and cord blood growth peptides (IGF-I, IGF-II) were measured.

Main Results:

• Infants born to exercising mothers had significantly lower birth weight and body mass index (p<0.05).
• Exercise did not alter the reduction in maternal insulin sensitivity observed in late gestation (p=0.45).
• Offspring from the exercise group exhibited lower cord serum insulin-like growth factor I (IGF-I) and IGF-II levels (p<0.05).

Conclusions:

• Regular aerobic exercise in pregnancy is associated with reduced fetal growth, indicated by lower birth weights.
• Exercise appears to influence fetal growth through mechanisms other than altering maternal insulin sensitivity.
• Reduced cord concentrations of growth peptides suggest exercise impacts endocrine regulation of fetal development.