Cruikshank D P, Pitkin R M, Reynolds W A, Williams G A, Hargis G K
Am J Obstet Gynecol. 1980 Mar 1;136(5):621-5. doi: 10.1016/0002-9378(80)91013-3.
Concentrations of the hormones and ions involved in calcium homeostasis were analyzed in simultaneous samples of amniotic fluid and maternal blood obtained from normal pregnant women between 14 weeks' gestation and term. Amniotic fluid total calcium, magnesium, and phosphorus levels fell progressively and markedly despite constant or only declining maternal serum levels. Ionized calcium was constant in both amniotic fluid (mean 2.22 mEq/L) and maternal serum (mean 2.33 mEq/L) throughout gestation. Parathyroid hormone levels in amniotic fluid declined after 20 weeks' gestation, despite rising maternal serum levels, consistent with suppressed fetal parathyroid activity secondary to the relative hypercalcemia of late fetal life. Calcitonin levels in both amniotic fluid and maternal serum were unchanged throughout gestation, with amniotic fluid levels being significantly lower than those in maternal serum.
对妊娠14周与足月之间的正常孕妇羊水和母血同步样本中参与钙稳态的激素和离子浓度进行了分析。尽管母体血清水平保持不变或仅下降，但羊水总钙、镁和磷水平逐渐且显著下降。整个妊娠期羊水和母血中的离子钙均保持恒定（羊水平均为2.22 mEq/L，母血平均为2.33 mEq/L）。尽管母体血清水平升高，但妊娠20周后羊水中甲状旁腺激素水平下降，这与胎儿晚期相对高钙血症继发的胎儿甲状旁腺活动受抑制一致。整个妊娠期羊水和母血中的降钙素水平均无变化，羊水水平显著低于母血水平。
