title: Changes in bone mineral density and body composition during pregnancy and postpartum. A controlled cohort study.
abstract: In a controlled cohort study, bone mineral density (BMD) was measured in 153 women pre-pregnancy; during pregnancy; and 0.5, 4, 9, and 19 months postpartum. Seventy-five age-matched controls, without pregnancy plans, were followed in parallel. Pregnancy and breastfeeding cause a reversible bone loss, which, initially, is most pronounced at trabecular sites but also involves cortical sites during prolonged breastfeeding.
  
  
  BACKGROUND
  Conflicting results have been reported on effects of pregnancy and breastfeeding on BMD and body composition (BC). In a controlled cohort study, we elucidate changes in BMD and BC during and following a pregnancy.
  
  
  METHODS
  We measured BMD and BC in 153 women planning pregnancy (n = 92 conceived), once in each trimester during pregnancy and 15, 129, and 280 days postpartum. Moreover, BMD was measured 19 months postpartum (n = 31). Seventy-five age-matched controls, without pregnancy plans, were followed in parallel.
  
  
  RESULTS
  Compared with controls, BMD decreased significantly during pregnancy by 1.8 ± 0.5% at the lumbar spine, 3.2 ± 0.5% at the total hip, 2.4 ± 0.3% at the whole body, and 4.2 ± 0.7% at the ultra distal forearm. Postpartum, BMD decreased further with an effect of breastfeeding. At 9 months postpartum, women who had breastfed for <9 months had a BMD similar to that of the controls, whereas BMD at the lumbar spine and hip was decreased in women who were still breastfeeding. During prolonged breastfeeding, BMD at sites which consist of mostly trabecular bone started to be regained, whereas BMD at sites rich in cortical bone decreased further. At 19 months postpartum, BMD did not differ from baseline at any site. During pregnancy, fat- and lean-tissue mass increased by 19 ± 22% and 5 ± 6% (p < 0.001), respectively. Postpartum, changes in fat mass differed according to breastfeeding status with a slower decline in women who continued breastfeeding. Calcium and vitamin D intake was not associated with BMD changes.
  
  
  CONCLUSIONS
  Pregnancy and breastfeeding cause a reversible bone loss. At 19 months postpartum, BMD has returned to pre-pregnancy level independently of breastfeeding length. Reversal of changes in fat mass depends on breastfeeding status.
authors: Department of Endocrinology and Internal Medicine, MEA, Aarhus Sygehus, Aarhus University Hospital, Tage Hansens Gade 2, DK-8000, Aarhus C, Denmark. kristine.moller@ki.au.dk
authors: U K
authors: UK
authors: Møller
authors: S
authors: S
authors: Við Streym
authors: L
authors: L
authors: Mosekilde
authors: L
authors: L
authors: Rejnmark
references: J Bone Miner Res. 2000 Jan;15(1):129-37
references: 10646122
references: Eur J Endocrinol. 1994 Oct;131(4):369-74
references: 7921225
references: Osteoporos Int. 2001;12(9):732-7
references: 11605738
references: Bone. 2003 Apr;32(4):449-54
references: 12689690
references: Am J Clin Nutr. 1998 Apr;67(4):693-701
references: 9537616
references: Br J Obstet Gynaecol. 1999 May;106(5):432-8
references: 10430193
references: Endocr Rev. 1997 Dec;18(6):832-72
references: 9408745
references: J Clin Endocrinol Metab. 1971 Oct;33(4):661-70
references: 5093770
references: Am J Clin Nutr. 1997 Jun;65(6):1738-46
references: 9174469
references: Horm Metab Res. 2003 May;35(5):313-8
references: 12916002
references: J Nutr. 1998 Feb;128(2 Suppl):381S-385S
references: 9478031
references: Osteoporos Int. 1999;10(1):41-6
references: 10501778
references: J Bone Miner Res. 1995 Sep;10(9):1312-20
references: 7502702
references: Obstet Gynecol. 1999 Oct;94(4):608-15
references: 10511368
references: Osteoporos Int. 2001;12(10):828-34
references: 11716185
references: Am J Clin Nutr. 1997 Feb;65(2):432-8
references: 9022527
references: Am J Clin Nutr. 1995 Mar;61(3):514-23
references: 7872214
references: Osteoporos Int. 1993;3 Suppl 1:44-7
references: 8461575
references: Am J Clin Nutr. 1993 Aug;58(2):162-6
references: 8338042
references: Am J Clin Nutr. 2008 Oct;88(4):1032-9
references: 18842791
references: Bone Miner. 1991 Aug;14(2):153-60
references: 1912763
references: J Bone Miner Res. 1989 Jun;4(3):283-91
references: 2763869
references: Bone. 2004 Mar;34(3):570-8
references: 15003805
references: Br J Obstet Gynaecol. 1988 Sep;95(9):849-54
references: 3191057
references: J Bone Miner Res. 2000 Mar;15(3):557-63
references: 10750571
references: Am J Med. 1986 Sep;81(3):451-6
references: 3755867
references: Osteoporos Int. 2000;11(5):449-54
references: 10912848
references: Arch Gynecol Obstet. 2003 Oct;268(4):309-16
references: 14504876
references: J Clin Endocrinol Metab. 1996 Jun;81(6):2314-8
references: 8964870
references: Clin Sci (Lond). 1998 Apr;94(4):405-12
references: 9640346
references: J Nutr. 2000 Apr;130(4):777-83
references: 10736329
references: Am J Clin Nutr. 1995 Feb;61(2):287-95
references: 7840065
references: Endocrine. 2002 Feb;17(1):49-53
references: 12014704
references: Obstet Gynecol. 1991 Jun;77(6):841-5
references: 2030854
references: Osteoporos Int. 1996;6(2):153-9
references: 8704355