RANDOMIZED CALCIUM TRIAL IN HIGH RISK PREGNANCIES

根据美国的说法。食物和营养委员会，推荐日报 怀孕期间钙的摄入量(RDA)为1200毫克/天。的RDA 青春期的年龄也是1200毫克/天。没有 建议增加钙的摄入量，以满足假定的 怀孕的青少年或多胎妊娠需要更多的钙 妊娠：特别是在怀孕期间钙和骨代谢的变化 这些高危妊娠，以及钙摄入量对 母体钙和骨代谢尚不清楚。最近的研究表明 怀孕期间传统的膳食钙摄入量可能是 不足以维持正钙平衡和最佳骨骼 新陈代谢，几项研究也证明了 低钙状态与糖尿病高发病率的关系 妊娠期高血压，可能导致显著的新生儿 发病率。从理论上讲，钙失衡可能发生在以下情况下 对胎儿高钙摄取的需求，例如在青少年怀孕期间， 在多胎妊娠中也是如此，因为怀孕发生在 母体骨骼生长活跃期。这样做的总体目标是 纵向随机试验是为了确定是否有 母体血钙显著变化，钙调节 青春期妊娠和成年期间的激素和骨量指数 多胎妊娠，以及这些变化是否受饮食影响 钙摄入量。需要检验的假设是：L)有一个更大的 对钙的需求和血清钙调节的更大幅度增加 青春期妊娠的激素浓度(甲状旁腺素和骨化三醇) 与成年单胎妊娠相比，成人多胎妊娠；以及， 2)怀孕的青少年和多胎妊娠的女性 随机接受补钙(1000毫克/天)会有较少的 血清钙降低，血清甲状旁腺素和甲状旁腺素增加较少 将怀孕期间的骨化三醇与类似的妇女进行比较 安慰剂。骨代谢生化指标的变化 (骨钙素、血清羧基末端前肽和血清交联物 I型胶原的端肽)也将被研究。审判将会 对336名孕妇进行了检查。参与者将包括健康的 怀孕的女性，年龄在21岁到40岁之间，单身和 多胎妊娠，单身母亲年龄在12到20岁之间。本研究 将有助于理解钙和骨代谢以及钙 青春期妊娠和成年多胎妊娠的需求；以及 有助于了解高血压的病理生理机制 在怀孕期间。

According to the US. Food and Nutrition Board, the Recommended Daily Allowance (RDA) of calcium during pregnancy is 1200 mg/day. The RDA for the adolescent during the growing years is also 1200 mg/day. There is no recommendation for an increment in calcium intake to meet the presumably greater calcium needs of pregnant adolescents or for multiple gestation pregnancies: specifically calcium and bone metabolism changes during these higher risk pregnancies, and the effect of calcium intake on maternal calcium and bone metabolism are unclear. Recent studies suggest that conventional dietary calcium intake during pregnancy may be inadequate to maintain a positive calcium balance and optimal bone metabolism, and several studies have also demonstrated a direct relationship between low calcium status and higher incidence of hypertension during pregnancy which may lead to a significant neonatal morbidity. Theoretically, calcium imbalances may occur when there is a need for high fetal calcium accretion, such as in adolescent pregnancy, and also in multiple gestation, because pregnancy occurs during the period of active maternal bone growth. The overall objective of this longitudinal randomized trial is to determine whether there are significant alterations in maternal serum calcium, calcium regulatory hormone, and bone mass indices during adolescent pregnancy and adult multiple gestation, and whether these changes are influenced by dietary calcium intake. The hypotheses to be tested are: l) there is a greater need for calcium and a greater increase in serum calcium regulatory hormone concentration (PTH and calcitriol), among adolescent pregnancies and adult multiple gestations compared to adult singleton pregnancy; and, 2) pregnant adolescents and females with multiple gestation who are randomized to receive calcium supplement (1000 mg/day) will have less of a decrease in serum calcium, and less of an increase in serum PTH and calcitriol throughout pregnancy compared to similar women randomized to placebo. Changes in biochemical indicators of bone metabolism (Osteocalcin, serum carboxyterminal propeptide, and serum cross-linked telopeptide of type I collagen) also will be investigated. The trial will be conducted in 336 pregnant women. Participants will include healthy pregnant females between 21 and 40 years of age, with singleton and multiple gestations, and singleton mothers age 12 to 20 years. This study will aid in the understanding of calcium and bone metabolism and calcium requirements in adolescent pregnancy and adult multiple gestation; and may help in the understanding of the pathophysiology of hypertension during pregnancy.