Lactation, weaning, and calcium supplementation: effects on body composition in postpartum women.
BACKGROUND
Concern that long-term weight retention after pregnancy contributes to obesity underscores the need to identify factors that facilitate postpartum weight loss. Lactation is believed to facilitate postpartum weight loss and fat loss. Calcium intake also has been hypothesized to promote weight loss and fat loss.


OBJECTIVE
We addressed the following questions: 1) whether lactation enhances loss of fat mass, and 2) whether loss of fat mass during lactation and after weaning is greater in women receiving calcium supplementation than in women receiving placebo.


METHODS
We used data from 87 lactating and 81 nonlactating women enrolled in a randomized, double-blind, calcium supplementation trial from 2 wk to 6 mo postpartum and data from 76 previously lactating and 82 nonlactating women enrolled in a parallel trial from 6 to 12 mo postpartum. Body fat and lean masses were measured by using dual-energy X-ray absorptiometry.


RESULTS
Nonlactating women lost whole-body, arm, and leg fat at a faster rate than did lactating women between 2 wk and 6 mo postpartum (lactation group x time effect, P < or = 0.01). Fat mass of the trunk, arms, and legs decreased between 6 and 12 mo postpartum regardless of previous lactation status (time effect, P < or = 0.001). Calcium supplementation did not affect postpartum fat loss.


CONCLUSIONS
Body-composition changes occur differently in nonlactating and lactating women during the first 6 mo postpartum and occur at some sites until 12 mo postpartum regardless of previous lactation status. Clinicians should use caution when advising lactating mothers about expected rates of postpartum fat loss. Calcium supplementation (1 g/d) does not promote postpartum weight loss or fat loss.
Cincinnati Children's Hospital Medical Center, Division of General and Community Pediatrics, 3333 Burnet Avenue, MLC 7035, Cincinnati, OH 45229, USA. karen.wosje@cchmc.org
Karen S
KS
Wosje
Heidi J
HJ
Kalkwarf
D000273:Adipose Tissue; D000328:Adult; D001823:Body Composition / Q000187:drug effects*; D002118:Calcium / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007774:Lactation; D049590:Postpartum Period; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors; D014886:Weaning; D015431:Weight Loss / Q000187:drug effects*
D002118:Calcium