Effect of calcium supplementation in pregnancy on maternal bone outcomes in women with a low calcium intake

Medical Research Council Keneba, Keneba, The Gambia.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 08/2010; 92(2):450-7. DOI: 10.3945/ajcn.2010.29217
Source: PubMed


Mobilization of maternal bone mineral partly supplies calcium for fetal and neonatal bone growth and development.
We investigated whether pregnant women with low calcium intakes may have a more extensive skeletal response postpartum that may compromise their short- or long-term bone health.
In a subset of participants (n = 125) in a double-blind, randomized, placebo-controlled trial (International Trial Registry: ISRCTN96502494) in pregnant women in The Gambia, West Africa, with low calcium intakes (approximately 350 mg Ca/d), we measured bone mineral status of the whole body, lumbar spine, and hip by using dual-energy X-ray absorptiometry and measured bone mineral status of the forearm by using single-photon absorptiometry at 2, 13, and 52 wk lactation. We collected blood and urine from the subjects at 20 wk gestation and at 13 wk postpartum. Participants received calcium carbonate (1500 mg Ca/d) or a matching placebo from 20 wk gestation to parturition; participants did not consume supplements during lactation.
Women who received the calcium supplement in pregnancy had significantly lower bone mineral content (BMC), bone area (BA), and bone mineral density (BMD) at the hip throughout 12 mo lactation (mean +/- SE difference: BMC = -10.7 +/- 3.7%, P = 0.005; BA = -3.8 +/- 1.9%, P = 0.05; BMD = -6.9 +/- 2.6%, P = 0.01). The women also experienced greater decreases in bone mineral during lactation at the lumbar spine and distal radius and had biochemical changes consistent with greater bone mineral mobilization.
Calcium supplementation in pregnant women with low calcium intakes may disrupt metabolic adaptation and may not benefit maternal bone health. Further study is required to determine if such effects persist long term or elicit compensatory changes in bone structure.

Download full-text


Available from: PubMed Central, Dec 17, 2014 · License: CC BY-NC
  • Source
    • "Among healthy American women, studies utilizing dual-energy X-ray absorptiometry (DXA) indicate that extended lactation (6 months) is associated with BMD losses of about 5% at the lumbar spine, with restoration of BMD to pre-pregnancy values by 12 months post-partum (Sowers et al., 1993). In contrast, DXA studies of rural Gambian women, who have high fertility , closely spaced births, on-demand breastfeeding for approximately 2 years, and low calcium intake, indicate incomplete restoration of lumbar spine BMD to prepregnancy values by 12 months post-partum (Jarjou et al., 2010). Complete BMD restoration among Gambian women may occur later in lactation or after weaning (Sawo et al., 2013). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Evolutionary theories of aging posit that greater reproductive effort causes somatic decline given a fundamental trade-off between investing energy in reproduction and repair. Few studies in high fertility human populations support this hypothesis, and problems of phenotypic correlation can obscure the expected trade-off between reproduction and somatic condition. This cross-sectional study investigates whether greater reproductive effort is associated with reduced calcaneal bone mineral density (BMD) among female Tsimane forager-farmers of lowland Bolivia. We also investigate whether female Tsimane BMD values are lower than sex- and age-matched US reference values, despite the fact that Tsimane engage in higher physical activity levels that can increase mechanical loading. To measure calcaneal BMD, quantitative ultrasonography was performed on 130 women (mean ± SD age = 36.6 ± 15.7, range = 15 – 75) that were recruited regardless of past or current reproductive status. Anthropometric and demographic data were collected during routine medical exams. As predicted, higher parity, short inter-birth interval, and earlier age at first birth are associated with reduced BMD among Tsimane women after adjusting for potential confounders. Population-level differences are apparent prior to the onset of reproduction, and age-related decline in BMD is greater among Tsimane compared to American women. Greater cumulative reproductive burden may lower calcaneal BMD individually and jointly with other lifestyle and heritable factors. Fitness impacts of kin transfers in adulthood may determine the value of investments in bone remodeling, and thus affect selection on age-profiles of bone mineral loss.
    Full-text · Article · Apr 2015 · American Journal of Physical Anthropology
  • Source
    • "For example, in Nigeria low calcium concentrations in breast milk have been documented in mothers who have produced children with bone malformation, specifically rickets (Thacher et al., 2006). For humans, calcium concentrations in breast milk have little, if any, rela- tionship to immediate maternal diet or to supplementation during lactation, but may be more reflective of long-term dietary conditions (reviewed in Power et al., 1999; L€ onnerdal, 2000; Prentice, 2000, 2003; Jarjou et al., 2010). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Mother's milk provides building blocks necessary for infant development and growth postnatally. Minerals in milk are particularly important for infant skeletal development and may reflect maternal characteristics that are associated with the capacity to synthesize milk and sex-specific developmental priorities of the infant. Using a large sample of mother-infant dyads assigned to the outdoor breeding colony at the California National Primate Research Center (N=104), we investigated the relationship of milk calcium (Ca) and phosphorus (P) concentrations and the ratio of Ca/P to maternal and infant characteristics and to other milk variables. Ca and P are largely associated with casein micelles, and as expected, both Ca and P were positively correlated with protein concentrations in milk. Neither Ca nor P concentrations were associated with maternal parity. Mothers rearing daughters tended to produce higher mean Ca concentration in milk, and consequently a higher Ca/P ratio, than did mothers rearing sons, even though protein concentration was not elevated. These results suggest that the Ca/P ratio in rhesus milk may have been under separate selective pressure from protein content to facilitate the accelerated rate of skeletal calcification that has been observed in female Macaca mulatta infants. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.
    Full-text · Article · May 2013 · American Journal of Physical Anthropology
  • Source
    • "Little change in the maternal bone mineral status (bone mineral density or content) is observed, although an increase in bone remodelling is reported [3, 4]. During lactation, bone resorption and renal calcium conservation are increased in both Western and Gambian women with concomitant decreases in bone mineral status [1, 5–7]. Changes in maternal bone mineral status and bone resorption during pregnancy and lactation appear to be independent of calcium intake in populations with a wide range of habitual calcium intakes [3, 4]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: This pilot study in women from The Gambia with low habitual calcium intakes showed differences in calciotropic hormones between pregnant, lactating and non-pregnant, non-lactating women similar to those in Western women. The response to oral calcium loading indicates a high degree of calcium conservation independent of reproductive status. Introduction In pregnancy and early lactation, parathyroid hormone (PTH) concentrations may be suppressed. Uncertainty exists about how calcium metabolism is regulated, particularly when calcium intake is low. Methods We investigated fasting markers of calcium metabolism and the acute calcemic and calciuric responses after an oral calcium load in 30 pregnant, lactating or non-pregnant, non-lactating (NPNL) Gambian women with low habitual calcium intakes. Women received 1 g elemental calcium (CaCO3) at 0 min. Blood was collected at −30 and 180 min. Urine was collected from −60 to 0, 0–120 and 120–240 min. Samples were analysed (blood: ionized calcium (iCa); plasma (p): total calcium (tCa), phosphate (P), creatinine (Cr), PTH, 1,25-dihydroxyvitamin D (1,25(OH)2D), osteocalcin (OC), β C-terminal cross-linked telopeptide of type 1 collagen (βCTX), cyclic adenosine monophosphate (cAMP); urine (u): Ca, P, Cr, cAMP). Results Pre-loading, groups did not differ significantly in iCa, pP, uCa/Cr and uP/Cr. pOC concentrations were significantly lower and NcAMP and p1,25(OH)2D higher in pregnant women; pPTH and pβCTX in lactating women were higher than in NPNL women. Post-loading, iCa, ptCa and uCa/Cr concentrations increased; pPTH, NcAMP, βCTX and uP/Cr decreased in all groups, but the magnitude of change did not differ significantly between groups. Conclusion Differences between pregnant, lactating and NPNL Gambian women in pPTH, NcAMP and p1,25(OH)2D and bone markers were similar to Western women. However, the response to calcium loading indicates that there may be no differences in renal and intestinal calcium economy associated with reproductive status, potentially due to a high degree of calcium conservation associated with low intakes.
    Preview · Article · Feb 2013 · Osteoporosis International
Show more