The Influence of Numerous Pregnancies and Lactations on Bone Dimensions in South African Bantu and Caucasian Mothers

Walker, Alexander; Richardson, B. D.; Walker, Faith M.

doi:10.1042/cs0420189

Cited by 86 publications

(22 citation statements)

References 25 publications

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“…The effect of pregnancy on maternal skeletal resorption is unclear. Determination of bone mass by photon absorption in the forearm [23] and radiographs of the metacarpals [24] has shown no change during gestation. However, it is now appreciated that appendicular skeletal loss as determined by photon absorption does not reflect axial skeletal loss [25].…”

Section: Discussionmentioning

confidence: 99%

Influence of pregnancy on immunoreactive parathyroid hormone levels

et al. 1982

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Summary. Parathyroid hormone (PTH) metabo-lism in pregnancy has not been clearly defined. Studies have reported either increased or unchanged values of immunoreactive PTH (iPTH). However, iPTH levels do not necessarily correlate with hormonal bioactivity due to the presence of immunoreactive but nonbioactive PTH fragments. In this study we evaluated PTH metabolism in the third trimester of pregnancy by determining iPTH blood levels as well as the biological effects of PTH, assessed by tubular maximum phosphate reabsorption (TmP) and nephrogenous cAMP (ncAMP) excretion, in 10 young, healthy pregnant patients (mean gestational age 35 weeks) and 10 young, healthy age-matched female controls. Pregnancy was associated with a significant increase in creatinine clearance (146 _+ 13 vs 106 _+ 9 ml/min, P < 0.01), and a significant decrease in total fasting serum calcium (8.4 _+ 0.1 vs 9.0 + 0.1 mg/dl, P < 0.001) and serum albumin (3.6 _+ 0.1 vs 4.2 +_ 0.1 g/dl, P < 0.001). There was no significant difference in iPTH (3.7 + 0.4 vs 4.3 _+ 0.5 /zlEq/ml), serum phosphorus (3.6 +_ 0.1 vs 3.8 __ 0.2 mg/dl), TraP (3.61 _+ 0.13 vs 3.75 + 0.25 mg/100 ml GFR), or ncAMP (1.68 +_ 0.20 vs 1.88 +_ 0.23 nmoles/100 ml GFR) between the two groups. Pregnancy was attended by a significant increase in fasting urinary calcium to creatinine ratio (0.14 +_ 0.03 vs 0.06 _+ 0.01, P < 0.05), an index of bone resorption. The data suggest that the biological effects of PTH are unchanged in pregnancy, and that reported increments in 1,25(OH)2 vitamin D in pregnancy are not regulated by changes in either PTH, calcium, or phosphate. terminal [12] fragments. These differences may reflect the use of different antibodies to PTH. Alternatively, even though serum concentrations of iPTH are normal in pregnant women [11,12], an increased turnover of the hormone is not excluded. Since the carboxy-terminal fragment of PTH is largely removed from the circulation by glomerular filtration [13], and since glomerular filtration increases during pregnancy, iPTH levels as determined by antibodies to the carboxy-terminal fragment may not reflect in vivo hormonal activity. To evaluate the effects of pregnancy on the biological effects of PTH, we have measured nephrogenous cyclic AMP (ncAMP), a sensitive indicator of in vivo PTH activity [14,15], and the tubular maximum phosphate reabsorption (TmP) [16,17] in 10 pregnant and 10 nonpregnant young women and correlated these values with serum levels of iPTH employing an antiserum to the carboxy-terminal fragment. We found that neither iPTH levels, ncAMP, nor TmP was altered during the third 0171-967X/82/0034-0009 $01.00

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Section: Discussionmentioning

confidence: 99%

Influence of pregnancy on immunoreactive parathyroid hormone levels

et al. 1982

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“…However, over five dozen epidemiologic studies of pre-, peri-, and postmenopausal women have found a neutral effect (16,38,63,158,203,214,215,290,292,299,341,356,368,379,383,397,444,445,448,463,481,506,509,541,547,611,619,625,636,648,683,700,761,828,845,846,861,864,865,869,879,934,935,944,951,969,1020) or a protective effect (25,27,71,…”

Section: Human Datamentioning

confidence: 99%

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

Kovacs

2016

Physiological Reviews

383

524

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During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ϳ30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

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“…Some studies reported higher BMD later in life with increased lactation [4][5][6][7], while others found lower BMD [8,9] or no association [10][11][12][13]. Nevertheless, a general view is that breastfeeding does not increase risk of fracture in later life [14][15][16].…”

Section: Introductionmentioning

confidence: 99%