Changes in calcitropic hormones, bone markers and insulin-like growth factor I (IGF-I) during pregnancy and postpartum: a controlled cohort study

Osteoporos Int. 2013 Apr;24(4):1307-20. doi: 10.1007/s00198-012-2062-2. Epub 2012 Aug 2.


Pregnancy and lactation cause major changes in calcium homeostasis and bone metabolism. This population-based cohort study presents the physiological changes in biochemical indices of calcium homeostasis and bone metabolism during pregnancy and lactation

Introduction: We describe physiological changes in calcium homeostasis, calcitropic hormones and bone metabolism during pregnancy and lactation.

Methods: We studied 153 women planning pregnancy (n=92 conceived) and 52 non-pregnant, age-matched female controls. Samples were collected prior to pregnancy, once each trimester and 2, 16 and 36 weeks postpartum. The controls were followed in parallel.

Results: P-estradiol (E2), prolactin and 1,25-dihydroxyvitamin D (1,25(OH)2D) increased (p<0.001) during pregnancy, whereas plasma levels of parathyroid hormone (P-PTH) and calcitonin decreased (p<0.01). Insulin-like growth factor I (IGF-I) was suppressed (p<0.05) in early pregnancy but peaked in the third trimester. Postpartum, E2 was low (p<0.05); prolactin decreased according to lactation status (p<0.05). 1,25(OH)2D was normal and IGF-I was again reduced (p<0.05). P-PTH and calcitonin increased postpartum. From early pregnancy, markers of bone resorption and formation rose and fall, respectively (p<0.001). From the third trimester, bone formation markers increased in association with IGF-I changes (p<0.01). Postpartum increases in bone turnover markers were associated with lactation status (p<0.001). During lactation, plasma phosphate was increased, whereas calcium levels tended to be decreased which may stimulate PTH levels during and after prolonged lactation.

Conclusion: The increased calcium requirements in early pregnancy are not completely offset by increased intestinal calcium absorption caused by high 1,25(OH)2D since changes in bone markers indicated a negative bone balance. The rise in bone formation in late pregnancy may be initiated by a spike in IGF-I levels. The high bone turnover in lactating women may be related to high prolactin and PTH levels, low E2 levels and perhaps increased parathyroid hormone-related protein levels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomarkers / blood
  • Bone Remodeling / physiology
  • Bone and Bones / metabolism*
  • Calcitonin / blood
  • Calcium / blood
  • Case-Control Studies
  • Estradiol / blood
  • Female
  • Homeostasis / physiology
  • Hormones / blood*
  • Humans
  • Insulin-Like Growth Factor I / metabolism*
  • Lactation / blood
  • Osteogenesis / physiology
  • Parathyroid Hormone / blood
  • Postpartum Period / blood*
  • Postpartum Period / physiology
  • Pregnancy / blood*
  • Pregnancy / physiology
  • Prolactin / blood
  • Vitamin D / analogs & derivatives
  • Vitamin D / blood


  • Biomarkers
  • Hormones
  • Parathyroid Hormone
  • Vitamin D
  • Estradiol
  • 1,25-dihydroxyvitamin D
  • Insulin-Like Growth Factor I
  • Prolactin
  • Calcitonin
  • Calcium