Association between regular exercise and excessive newborn birth weight.

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Public Health

Background:

• Excessive newborn birth weight is a significant concern in maternal and child health.
• Identifying modifiable factors like exercise can inform public health strategies.
• Previous research has explored exercise during pregnancy, but specific associations with birth weight require further elucidation.

Purpose of the Study:

• To investigate the association between regular exercise before and during pregnancy and the incidence of excessive newborn birth weight.
• To differentiate effects based on parity (nulliparous vs. multiparous women).

Main Methods:

• Utilized data from the Norwegian Mother and Child Cohort Study (36,869 singleton pregnancies).
• Assessed regular exercise via questionnaires at 17 and 30 weeks of gestation.
• Defined excessive newborn birth weight as birth weight at or above the 90th percentile.
• Employed logistic regression to calculate adjusted odds ratios (aORs) for nulliparous and multiparous women.

Main Results:

• Excessive newborn birth weight occurred in 10.9% of newborns.
• Regular exercise (≥3 times/week) during pregnancy was inversely associated with excessive birth weight in nulliparous women (aOR 0.72-0.77).
• Exercise before pregnancy showed no significant association with excessive birth weight in either nulliparous or multiparous women.

Conclusions:

• Regular exercise during pregnancy is associated with a reduced likelihood of delivering newborns with excessive birth weight, particularly in nulliparous women.
• The findings suggest a protective effect of consistent exercise during gestation.
• Exercise performed prior to pregnancy did not demonstrate a similar protective effect on birth weight outcomes.