Effect of prenatal calcium supplementation on bone during pregnancy and 1 y postpartum (original) (raw)
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Nutrition journal, 2014
Calcium needs are physiologically upregulated during pregnancy and lactation to meet demands of the developing fetus and breastfeeding infant. Maternal calcium homeostasis is maintained by hormonal adaptive mechanisms, thus, the role of dietary calcium supplementation in altering maternal responses to fetal-infant demand for calcium is thought to be limited. However, increased calcium absorption is directly related to maternal calcium intake and dietary supplementation has been suggested to prevent transient bone loss associated with childbearing. In a double-blind, randomized placebo-controlled trial, we randomly assigned 670 women in their first trimester of pregnancy to 1,200 mg/day calcium (N = 334) or placebo (N = 336). Subjects were followed through 1-month postpartum and the effect on urinary cross-linked N-telopeptides (NTx) of type I collagen, a specific marker of bone resorption, was evaluated using an intent-to-treat analysis. Women with a baseline and at least one follow...
The American journal …, 1995
Ten women were followed serially to determine the effect of stages of reproduction on calcium and bone metabolism. The study periods were nonpregnant nonlactating, the end of each trimester of gestation, 3 mo lactation, and postweaning. Comparisons were with nonpregnant nonlactating status for each individual. Fractional calcium absorption (P < 0.0001) and concentrations of 1,25-dihydroxyvitamin D (P < 0.01) were higher in the second and third trimesters. Total urinary calcium was higher during pregnancy and lower postweaning. Parathyroid hormone (PTH) concentrations were higher only postweaning (P < 0.01). Markers of bone turnover increased at the third trimester and during lactation: serum tantrate resistant acid phosphatase and bone specific alkaline phosphatase, and urinary deoxypyridinoline (P < 0.01). Serum procollagen I carboxypeptides increased only in the third tnmesten (P < 0.01). Bone mineral density by single-photon absorptiometry did not differ by period. We conclude that absorption and urinary excretion of calcium increase during pregnancy whereas bone turnover increases during late pregnancy and lactation; only renal changes consistent with an increase in PTH were seen postweaning.
Bone, 2003
This longitudinal study evaluated bone turnover and the interrelationship between changes in bone biomarkers and habitual dietary calcium intake during pregnancy in a group of women ranging widely with regard to dietary calcium intake. Thirty-nine healthy pregnant and 30 nonpregnant women were studied. Calcium, phosphorus, 1␣,25-dihydroxyvitamin D (1,25diHOD), bone alkaline phosphatase (bALP), carboxyterminal propeptides of type I procollagen (PICP) and carboxyterminal telopeptides of type I collagen (CTX and ICTP) were measured in serum and calcium, and creatinine and aminoterminal telopeptide (NTX) were determined in urine. Serum calcium and phosphorus did not change but the urinary Ca/Creat ratio and 1,25diHOD increased throughout pregnancy (P Ͻ 0.001 and P Ͻ 0.0001, respectively). Serum b-ALP and PICP increased during the last two trimesters (P Ͻ 0.0001 and P Ͻ 0.001, respectively). All studied bone resorption markers increased compared to nonpregnant values throughout pregnancy. The highest increment was observed in the third trimester. The level of significance decreased as follows: CTX Ͼ NTX ϾICTP. Serum 1,25 diHOD versus calcium intake showed a positive and significant correlation (r ϭ 0.51, P Ͻ 0.02). A negative correlation between the absolute change in CTX, NTX, and b-ALP between the third and second trimester and calcium intake at the end of pregnancy was observed in pregnant women who did not cover adequately calcium intake requirements (r ϭ Ϫ0.47, P Ͻ 0.03; r ϭ Ϫ0.41, P Ͻ 0.05; and r ϭ Ϫ0.43, P Ͻ 0.05, respectively). These results suggest that skeletal response to pregnancy may not be entirely independent of maternal calcium intake, especially in women with usually low calcium intake. In summary, not only hormonal changes in calcium metabolism that occur during pregnancy but also other considerations, such as low dietary calcium intake, may lead to an increment in the biological activity of the skeleton. Additional studies must be conducted to confirm our findings and to gain a better understanding of skeletal response to a low calcium intake during pregnancy.
American Journal of Clinical Nutrition, 2012
Background: Factors affecting bone calcium deposition across pregnancy and lactation are not well characterized. Objective: The impact of maternal age, calcium intake, raceethnicity, and vitamin D status on the rate of bone calcium deposition (VO+) was assessed across pregnancy and lactation. Design: Stable calcium isotopes were given to 46 women at pre-or early pregnancy (trimester 1), late pregnancy (trimester 3), and 3-10 wk postpartum. Three cohorts were included: 23 adolescents from Baltimore (MD), aged 16.5 6 1.4 y (mean 6 SD; Baltimore cohort); 13 adults from California, aged 29.5 6 2.6 y (California cohort); and 10 adults from Brazil, aged 30.4 6 4.0 y (Brazil cohort). The total exchangeable calcium pool, VO+, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D [1,25(OH) 2 D], parathyroid hormone, and calcium intake were evaluated. Results: At trimester 3, inverse associations between 1,25(OH) 2 D and VO+ were evident in the Baltimore (P = 0.059) and Brazil (P = 0.008) cohorts and in the whole group (P = 0.029); calcium intake was not a significant determinant of VO+ in any group during pregnancy. At postpartum, a significant positive association was evident between VO+ and calcium intake (P 0.002) and between VO+ and African ethnicity (P 0.004) in the whole group and within the Baltimore and Brazil cohorts. Conclusions: Elevated 1,25(OH) 2 D was associated with decreased rates of bone calcium deposition during late pregnancy, a finding that was particularly evident in pregnant adolescents and adult women with low calcium intakes. Higher dietary calcium intakes and African ethnicity were associated with elevated rates of bone calcium deposition in the postpartum period.
The American Journal of Clinical Nutrition, 2006
Background: Few data exist on longitudinal changes in bone calcium turnover rates across pregnancy and lactation. Objective: Our aim was to characterize calcium kinetic variables and predictors of these changes across pregnancy and early lactation in women with low calcium intakes. Design: Stable calcium isotopes were administered to 10 Brazilian women during early pregnancy (EP; weeks 10-12 of gestation), late pregnancy (LP; weeks 34-36 of gestation), and early lactation (EL; 7-8 wk postpartum). Multicompartmental modeling was used to assess the rates of bone calcium turnover in relation to calcium intakes and circulating concentrations of parathyroid hormone (PTH), insulin-like growth factor 1, and 1,25-dihydroxyvitamin D. Results: Rates of bone calcium deposition increased significantly from EP to LP (P ҃ 0.001) and were significantly associated with serum PTH during LP (P ͨ 0.01). Rates of bone calcium resorption were also higher during LP and EL than during EP (P ͨ 0.01) and were associated with both PTH (P ͨ 0.01) and IGF-1 (P ͨ 0.05) during LP but not during EL. Net balance in bone calcium turnover was positively associated with dietary calcium during EP (P ͨ 0.01), LP (P ͨ 0.01), and EL (P ͨ 0.01). The mean (ȀSD) calcium intake was 463 Ȁ 182 mg/d and, in combination with insulin-like growth factor 1, explained 68-94% of the variability in net bone calcium balance during pregnancy and lactation. Conclusions: Net deficits in bone calcium balance occurred during pregnancy and lactation. Increased dietary calcium intake was associated with improved calcium balance; therefore, greater calcium intakes may minimize bone loss across pregnancy and lactation in women with habitual intakes of 500 mg calcium/d.
Role of calcium during pregnancy: maternal and fetal needs
Although the demand for additional calcium during pregnancy is recognized, the dietary reference intake for calcium was lowered for pregnant women in 1997 to amounts recommended for nonpregnant women (1,000 mg/day), and recently (November 2010) the Institute of Medicine report upheld the 1997 recommendation. It has been frequently reported that women of childbearing age do not consume the dietary reference intake for calcium and that calcium intake in the United States varies among ethnic groups. Women who chronically consume suboptimal amounts of calcium (<500 mg/day) may be at risk for increased bone loss during pregnancy. Women who begin pregnancy with adequate intake may not need additional calcium, but women with suboptimal intakes (<500 mg) may need additional amounts to meet both maternal and fetal bone requirements. The objective of this review is to elucidate the changes in calcium metabolism that occur during pregnancy as well as the effect of maternal calcium intake on both maternal and fetal outcomes.
Maternal calcium supplementation and fetal bone mineralization
Obstetrics and Gynecology, 1999
Objective: To determine the effect of maternal calcium supplementation during pregnancy on fetal bone mineralization.Methods: Healthy mothers with early ultrasound confirmation of dates and singleton pregnancies were enrolled in a double-masked study and randomized before 22 weeks’ gestation to 2 g/day of elemental calcium or placebo until delivery. Maternal dietary intake at randomization and at 32–33 weeks’ gestation was recorded with 24-hour dietary recalls. Dual-energy x-ray absorptiometry measurements of the whole body and lumbar spine of the neonates were performed before hospital discharge.Results: The infants of 256 women (128 per group) had dual-energy x-ray absorptiometry measurements during the first week of life. There were no significant differences between treatment groups in gestational age, birth weight, or length of the infants, or in the total-body or lumbar spine bone mineral content. However, when bone mineral content was analyzed by treatment group within quintiles of maternal dietary calcium intake, total body bone mineral content (mean ± standard error of the mean) was significantly greater in infants born to calcium-supplemented mothers (64.1 ± 3.2 versus 55.7 ± 2.7 g in the placebo group) in the lowest quintile of dietary calcium intake (less than 600 mg/day). The effect of calcium supplementation remained significant after adjustment for maternal age and maternal body mass index and after normalization for skeletal area and body length of the infant.Conclusion: Maternal calcium supplementation of up to 2 g/day during the second and third trimesters can increase fetal bone mineralization in women with low dietary calcium intake. However, calcium supplementation in pregnant women with adequate dietary calcium intake is unlikely to result in major improvement in fetal bone mineralization.
The Effects of Pregnancy and Lactation on Bone Mineral Density
Osteoporosis International, 2001
We performed a prospective study of bone mineral density (BMD) in 38 women during their first full-term pregnancy until 12 months postpartum. BMD measurements at lumbar spine [L2-L4 (LS)] and forearm [distal 33% (RD) and ultradistal (RUD) region of the radius] were made within 3 months before conception, after delivery, and at 6 and 12 months postpartum. In mid-pregnancy the DXA examination was carried out only at the forearm. Patients were grouped according to duration of lactation as group I, II or III (0-1, 1-6, 6-12 months respectively). During pregnancy there was a significant difference between baseline and delivery (p< 0.001) in the LS, RUD and RD BMD values. In group I there was no statistically significant difference in LS BMD between visits following pregnancy. The RUD BMD loss was recovered by 6 months postpartum (PP6). Group II showed continuous bone loss from delivery until PP6 at LS and RUD. In group III the LS BMD loss continued throughout the lactation period. The RUD BMD dropped (4.9%) until PP6 then increased by 3.0% as measured at 12 months postpartum (PP12). There was no significant change in RD BMD in any of three groups during lactation. At LS bone loss between delivery and PP12 correlated well with the duration of lactation (r = 70.727; p<0.001). We suggest that calcium needed for fetal skeletal growth during pregnancy was gained from maternal trabecular and cortical sites and that calcium needed for infant growth during lactation was drawn mainly from the maternal trabecular skeleton in our patients. The effect of pregnancy and lactation on the maternal bone mass was spontaneously compensated after weaning.
Journal of Bone and …, 1995
A randomized clinical intervention trial to determine effects of lactation and 1 g of calcium (Ca) on bone remodeling was conducted in 15 women (calcium = 7, placebo [PI = 8) consuming 13-2.4 g of Ca/day from diet + prenatal supplement. Study periods were baseline, 5 2 weeks postpartum; lactation, 3 months lactation; and postweaning, 3 months postweaning. Bone mineral density (BMD) corrected for body weight was determined by dual-energy X-ray absorptiometry (DXA). Indicators of calcium metabolism, bone turnover, and lactation were measured: calcium metabolism, parathyroid hormone (PTH), 25-hydroxyvitamin D (25 [OH] D), 1,25-dihydroxyvitamin D (1,25 [OH],D); bone turnover, formation, procollagen I carboxypeptides (PICP), osteocalcin, and bone alkaline phosphatase (B-ALP), resorption, tartrate resistant acid phosphatase (TRAP); and lactation, prolactin (PRL). Mean BMD changes differed by site: baseline to lactation-43% (P) (p < 0.04) and-63% (Ca) (p < 0.01) at the lumbar spine (L2-U) and 5.7% gains of the ultradistal (UD) radius (Ca) (p < 0.04); lactation to postweaning,-6% to-11% at all sites of the radius and ulna (Ca, P) (p < 0.04) +3% at L2-U (Ca) (p < 0.03); baseline to postweaning, (UD) radius-5.2% (P) (p < 0.03), UD radius + ulna-6% to-8% (Ca, P) (p < 0.04) but no significant loss of L2-L4 or total body. Bone turnover markers were higher at lactation than postweaning: PICP (+34%,p < 0.001), osteocalcin (+25%,p < 0.01), TRAP (+ll%,p < 0.005) as was PRL (+81%,p < 0.001). Indicators of calcium metabolism were higher postweaning than lactation for PTH (+4wo,p < 0.01) and 25(OH)D (+45%, p < 0.02) but not for 1,25(OH),D. There were no differences between P or Ca for indices of calcium metabolism, bone turnover, or PRL. An increase in markers of bone turnover and a loss of BMD of the spine during lactation appears to be part of the physiological changes of lactation and not preventable by increasing calcium intake above the recommended dietary allowance (RDA). A return of BMD toward baseline of the spine but not the arm, was associated with an increase in PTH without an increase in 1,25(OH),D postweaning. Loss of estrogen during lactation and a return postweaning may play an important role.