Maternal weight gain rate in the second trimester are associated with birth weight and length of gestation.

Background: Low total weight gain during pregnancy has been widely accepted as a valid risk factor for small-for-gestational-age infants and pre-term births. However, it is not obvious in which trimester the weight gain rate most affects birth weight and length of gestation.

Method: Using logistic regression analysis and Pearson's correlation coefficient test, data from 472 women who had vaginally delivered an infant at term without any complications were analyzed retrospectively.