Postpartum weight change: how much of the weight gained in pregnancy will be lost after delivery?

In a large sample (N = 7116) of women who had two pregnancies within six years, the 50th percentile of weight gain between pregnancies was 2 lb (0.9 kg). Weight gain in pregnancy, week of registration, cigarette smoking, race, percent of ideal body weight, complications of pregnancy, and marital status in the first pregnancy, as well as breast-feeding in the hospital and interval between the two pregnancies, correlated significantly with interpregnancy weight change, and explained 24% of the variance (P less than .0001). Weight gain in the first pregnancy alone explained 21% of the variance in weight change between pregnancies. After adjustment for the effects of other variables on weight change, weight gains in pregnancy of 20 lb (9.1 kg) or more were statistically significant (P less than .05); the more weight a woman gained above 20 lb (9.1 kg), the more she retained by the start of her next pregnancy.