Low prepregnant body mass index and breastfeeding practices

The relationship of low prepregnant body mass index with breastfeeding was investigated in 1272 women who delivered a term infant with birthweight >= 2500 g at the San Paolo Hospital in Milan, Northern Italy. Underweight was defined using the Institute of Medicine's cutoff of 19.8 kg/m(2). Women were interviewed via telephone through 12 months postdelivery about breastfeeding practices. Education level (high versus low, odds ratio [OR], 1.41), primiparity (OR, 1.35), vaginal delivery (OR, 0.74), and birthweight of the infant (normal versus high, OR, 1.89) were associated with low, as opposed to normal, prepregnant body mass index. After adjustment for these confounders, no difference was found between underweight and normal weight women for initiation or duration of breastfeeding (mean adjusted difference, 0.4; 95% confidence interval [95% CI], -0.1 to 0.9 months) or exclusive breastfeeding (0.1 [95% CI, -0.1 to 0.3] months). Underweight mothers of healthy term infants may not be at increased risk for not initiating or shorter breastfeeding.