Calcium, Phosphorus, and Niacin Intakes During Late Pregnancy Are Positively Associated with Maternal Bone Mineral Density: A Pilot Study

Abstract Objectives The adequate calcium intake during pregnancy on postpartum bone mineral density (BMD) and neonatal outcomes are unknown as results of recent intervention trials are inconsistent. We investigated the relationship between maternal nutrient intake and maternal BMD at delivery, newborn birth outcomes, and maternal bone loss during lactation in Korean mothers. Methods Thirty Korean pregnant women (mean age: 34 years) were enrolled before delivery. Maternal food and supplement intake and BMD were assessed twice: at delivery (T1) and at weaning or 6 months postpartum (T2). Third trimester and postpartum food intake was assessed by food frequency questionnaire at T1 and T2, respectively, and analyzed for intake of calcium and 22 major nutrients. Calcium intake was assessed as a continuous variable or categorized as < or ≥500 mg/d. Maternal lumbar spine (LS), femoral neck (FN), trochanter, and intertrochanter BMD were measured by dual energy X-ray absorptiometry. Birth length, birth weight, and head circumference of neonates were collected. Participants were categorized according to duration of lactation. General linear models were adjusted for covariates. Results Mean ± STD calcium intake was 905 ± 430 mg/d at T1 and 608 ± 227 at T2 (change: P = 0.05). Women with calcium intakes <500 mg/d had lower LS BMD at T1 (P = 0.026). No difference was detected at other study sites. Phosphorus and niacin intakes during the third trimester were positively correlated with T1 LS BMD (ß: 0.162 and 0.088, respectively; both P < 0.05). Birth weight and head circumference were negatively associated with T1 iron intake(ß: −9.065 and −0.0292, respectively; both P < 0.05). Intake of other nutrients during late pregnancy were not associated with maternal T1 BMD or neonatal outcomes. Among the 10 participants that completed the second visit, 6 women breastfed. Postpartum bone change was not associated with breastfeeding. Energy intake at T2 was negatively associated with change in FN BMD (ß: −0.007, P < 0.001). Postpartum intake of other nutrients was not associated with change of BMD at any site. Conclusions Intakes of calcium, phosphorus, and niacin during the third trimester are positively associated with maternal LS BMD, but not neonatal birth outcomes, in Koreans. Breastfeeding and postpartum calcium intake may not affect bone after birth. Funding Sources National Research Foundation of Korea.