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钙、镁、磷三种物质从母体经由胎盘到达胎儿体内。母体血清钙随着妊娠进展逐渐下降,并于以后的连续妊娠时更低,在一年中的头五个月血清钙亦较低。血清钙的下降似乎是钙的离子部分。在分娩时,母体血清钙、镁、磷均比脐带血为低;然而婴儿在分娩后数小时内,血清钙与镁下降,而血无机磷则保持在比母体高的水平。出生后12与72小时的血清钙浓度直接与妊娠年龄有关,出生2一3日后与第1周内的血清钙浓度则主要决定于喂
Calcium, magnesium, phosphorus three substances from the mother through the placenta to reach the fetus. Maternal serum calcium declines gradually with the progress of pregnancy and is lower at subsequent consecutive pregnancies. Serum calcium is also lower in the first five months of the year. The decrease in serum calcium appears to be the ionic part of calcium. Maternal serum calcium, magnesium, and phosphorus were lower than cord blood at childbirth; however, serum calcium and magnesium decreased in infants within hours of delivery, whereas blood inorganic phosphorus remained high at maternal levels. Serum calcium concentrations at 12 and 72 hours after birth are directly related to gestational age, and serum calcium concentrations after 2 to 3 births and during the first week of life are mainly determined by feeding