Postpartum consequences of an overlap of breastfeeding and pregnancy: reduced breast milk intake and growth during early infancy.

OBJECTIVE Despite cultural pressure to wean when a new pregnancy occurs, some women choose to continue breastfeeding. We determined the effect of an overlap of lactation and late pregnancy on breastfeeding and growth in early infancy. METHODS We studied 133 Peruvian pregnant women who were > or =18 years of age, had a child <4 years old, and who then had a vaginal birth with a healthy, normal weight infant. Of the 133 women, 68 breastfed during the last trimester of pregnancy (BFP), and 65 had not breastfed during pregnancy (NBFP). On day 2 and at 1-month postpartum, 24-hour intake of breast milk and other liquids was measured. Twice weekly home surveillance documented infant morbidity and dietary intakes. Anthropometry was taken at birth and at 1 month. Maternal anthropometric, health, and socioeconomic status data were collected pre- and postpartum. RESULTS Pregnant BFP mothers breastfed 5.3 +/- 4.3 times/day. BFP and NBFP infants did not differ in breastfeeding behavior or in colostrum intake on day 2. BFP infants breastfed longer per feed and per 24 hours (35.2 minutes/24 hours) than did NBFP infants; however, 1-month intakes per feed tended to be lower among the BFP infants. After controlling for confounders, BFP infants gained 125 g less than did NBFP infants (about 15% of mean weight gain). A sustained decline would result in a -0.7 z score change in weight-for-age by 6 months. CONCLUSIONS A lactation-pregnancy overlap had a negative effect on early infant outcomes. Additional studies are needed to determine whether the effect continues past 1 month of age.