Calcium absorption is significantly higher in adolescents during pregnancy than in the early postpartum period

Kimberly O. O'Brien, Maureen Schulman Nathanson, Jeri Mancini, Frank R. Witter

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Background: Early childbearing may limit skeletal consolidation and increase calcium demands in adolescents. Objective: The purpose of this study was to characterize calcium absorption in pregnant and lactating adolescents. Design: Fractional calcium absorption was evaluated in 23 adolescents (mean ± SD age: 16.5 ± 1.4 y) during the third trimester of pregnancy (34.7 ± 1.0 wk gestation) and again in 15 of these adolescents 31 ± 8 d after delivery. Eight adolescents were breastfeeding their infants during the follow-up study. Fractional calcium absorption was determined by using oral (46Ca or 44Ca) and intravenous ( 42Ca) stable calcium isotopes. Total-body and lumbar spine bone mineral density were measured in adolescents during the postpartum period by using dual-energy X-ray absorptiometry. Results: Fractional calcium absorption was significantly greater during pregnancy than at 3-4 wk postpartum [0.526 ± 0.152 (n = 23) compared with 0.297 ± 0.108 (n = 15); P < 0.0001]. Lumbar spine z scores measured 19-44 d after delivery (n = 15) were significantly associated with calcium intake during pregnancy (y = -3.53 + 0.107x; R2 = 0.355, P < 0.02) and were inversely related to fractional calcium absorption during pregnancy (y = 3.489 - 6.66x; R2 = 0.52, P = 0.002). A total of 33% (5/15) of adolescents had lumbar spine z scores that met the definition of osteopenia (n = 3) or osteoporosis (n = 2) in the early postpartum period. Conclusions: Calcium absorption in adolescents was significantly higher during the third trimester of pregnancy than in the early postpartum period, and higher calcium intakes during pregnancy appeared to be protective against loss of trabecular bone at the lumbar spine.

Original languageEnglish (US)
Pages (from-to)1188-1193
Number of pages6
JournalAmerican Journal of Clinical Nutrition
Issue number6
StatePublished - Dec 2003


  • Adolescents
  • Bone
  • Calcium absorption
  • Lactation
  • Pregnancy
  • Stable isotopes

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics


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