Correlation between maternal weight gain during gestation and fetal and placental growth in rats.

In rats, maternal weight gain during the later third of pregnancy was correlated with fetal body weight, brain weight and DNA content as well as placental weight near term. Fetal body and placental growth was unrelated to maternal weight increases during pregnancy. A significant inverse correlation between fetal brain DNA content and maternal weight gain was found. This was related to litter size since the smaller the litter size, the less the maternal weight gain during pregnancy and the greater the DNA content of the fetal brain. These data emphasize the importance of controlling for litter number in growth studies.