Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA.
Am J Clin Nutr. 2012 Jul;96(1):64-72. doi: 10.3945/ajcn.111.029231. Epub 2012 May 30.
Factors affecting bone calcium deposition across pregnancy and lactation are not well characterized.
The impact of maternal age, calcium intake, race-ethnicity, and vitamin D status on the rate of bone calcium deposition (VO+) was assessed across pregnancy and lactation.
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 ± 1.4 y (mean ± SD; Baltimore cohort); 13 adults from California, aged 29.5 ± 2.6 y (California cohort); and 10 adults from Brazil, aged 30.4 ± 4.0 y (Brazil cohort). The total exchangeable calcium pool, VO+, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D [1,25(OH)₂D], parathyroid hormone, and calcium intake were evaluated.
At trimester 3, inverse associations between 1,25(OH)₂D 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.
Elevated 1,25(OH)₂D 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.
影响妊娠和哺乳期骨钙沉积的因素尚不清楚。
评估母亲年龄、钙摄入量、种族和维生素 D 状态对妊娠和哺乳期骨钙沉积率（VO+）的影响。
在妊娠前或早期妊娠（第 1 孕期）、晚期妊娠（第 3 孕期）和产后 3-10 周，给 46 名妇女服用稳定的钙同位素。纳入了 3 个队列：来自巴尔的摩（马里兰州）的 23 名青少年，年龄 16.5 ± 1.4 岁（均数 ± 标准差；巴尔的摩队列）；来自加利福尼亚的 13 名成年人，年龄 29.5 ± 2.6 岁（加利福尼亚队列）；和来自巴西的 10 名成年人，年龄 30.4 ± 4.0 岁（巴西队列）。评估了总可交换钙池、VO+、25-羟维生素 D、1,25-二羟维生素 D [1,25(OH)₂D]、甲状旁腺激素和钙摄入量。
在第 3 孕期，巴尔的摩（P = 0.059）和巴西（P = 0.008）队列以及整个组（P = 0.029）中，1,25(OH)₂D 与 VO+之间存在负相关；在妊娠期间，钙摄入量在任何组中都不是 VO+的显著决定因素。产后，整个组和巴尔的摩和巴西队列中，VO+与钙摄入量之间存在显著正相关（P ≤ 0.002），VO+与非洲裔之间存在显著正相关（P ≤ 0.004）。
在妊娠晚期，1,25(OH)₂D 升高与骨钙沉积率降低有关，这一发现尤其明显于低钙摄入的妊娠青少年和成年女性。较高的膳食钙摄入量和非洲裔与产后骨钙沉积率升高有关。
