Changes in maternal postpartum adiposity and infant feeding patterns.

The relationship between maternal fatness and infant feeding practices was studied in 46 healthy Caucasian women from parturition to 6 months postpartum. Mothers reported infant feeding practices in diary form throughout the study. Weight, triceps and subscapular skinfolds, and midarm circumference were measured on seven occasions. Upper arm fat area was computed. All women breast fed their infants for at least 5 months, with no nonbreast milk food introduced for at least 2 months. All women had declining or stable postpartum weights. Linear regressions of upper arm fat area on days since parturition were used to ascertain overall direction of change in adiposity for each woman. Declining fat area occurred in 17 cases and was associated with a breast-feeding pattern of short frequent feeds. In the remaining 29 cases, increasing fat area was associated with significantly longer and less frequent feeds. It is hypothesized that these different fat change patterns result from differential activity of adipose tissue lipoprotein lipase, which is itself mediated by serum prolactin concentration. Relevance of these findings for resolution of the controversy surrounding the critical body composition hypothesis and lactation amenorrhea is discussed.