Simpson J L, Elias S, Morgan C D, Andersen R N, Shulman L P, Sibai B M, Mercer B M, Skoll A
Department of Obstetrics and Gynecology, University of Tennessee, Memphis 38163.
Am J Obstet Gynecol. 1991 Mar;164(3):829-36. doi: 10.1016/0002-9378(91)90525-v.
Several reports have suggested that persons with an unexplained maternal serum alpha-fetoprotein elevation at 15 to 20 weeks' gestation are at an increased risk for a variety of other pregnancy complications (e.g., preeclampsia) and adverse perinatal outcomes (e.g., fetal death, low-birth-weight infants). However, ascertainment biases could explain some of these reported findings, and predictive value of unexplained elevated maternal serum alpha-fetoprotein levels in the prediction of pregnancy complications seems limited. If elevated second-trimester levels were truly predictive of pregnancy complications, we reason that third-trimester levels could prove even more useful. We thus studied late second-trimester and early third-trimester (24 to 36 weeks' gestation) maternal serum alpha-fetoprotein levels with the same enzyme immunoassay we use to evaluate routine second-trimester (15 to 20 weeks' gestation) levels. Values rose up to 32 weeks and fell slightly thereafter. Variance was greater than at 15 to 20 weeks but not so great as to preclude clinical usefulness in the third trimester. Of 279 women with a normal (0.4 to 2.49 multiples of the median) maternal serum alpha-fetoprotein value at 15 to 20 weeks' gestation, 270 (96.8%) showed levels in the same range later in gestation; however, none of six singleton pregnancies with unexplained maternal serum alpha-fetoprotein levels greater than 2.50 multiples of the median at 15 to 20 weeks' gestation showed maternal serum alpha-fetoprotein levels in this range at 24 to 36 weeks' gestation. The relationship between second- and third-trimester maternal serum alpha-fetoprotein levels in abnormal pregnancies remains to be elucidated in a large sample. Thus we are conducting not only cohort but also cross-sectional studies. Preliminary findings suggest that women with preterm premature rupture of membranes or with premature labor show elevated late second-trimester and early third-trimester maternal serum alpha-fetoprotein levels; however, larger sample sizes are necessary.
几份报告表明，在妊娠15至20周时母体血清甲胎蛋白升高原因不明的孕妇，发生各种其他妊娠并发症（如先兆子痫）和不良围产期结局（如胎儿死亡、低体重儿）的风险增加。然而，确定偏倚可能解释了这些报告中的一些发现，而且原因不明的母体血清甲胎蛋白水平升高在预测妊娠并发症方面的预测价值似乎有限。如果孕中期水平升高真的能预测妊娠并发症，我们推断孕晚期水平可能会更有用。因此，我们用我们用于评估常规孕中期（妊娠15至20周）水平的相同酶免疫测定法，研究了妊娠晚期（24至36周）和孕晚期（24至36周）的母体血清甲胎蛋白水平。数值在32周前上升，此后略有下降。其方差大于15至20周时，但不至于大到排除在孕晚期的临床实用性。在妊娠15至20周时母体血清甲胎蛋白值正常（中位数的0.4至2.49倍）的279名妇女中，270名（96.8%）在妊娠后期显示水平在同一范围内；然而，在妊娠15至20周时原因不明的母体血清甲胎蛋白水平大于中位数2.50倍的6例单胎妊娠中，没有一例在妊娠24至36周时母体血清甲胎蛋白水平在这个范围内。异常妊娠中孕中期和孕晚期母体血清甲胎蛋白水平之间的关系仍有待在大样本中阐明。因此，我们不仅在进行队列研究，也在进行横断面研究。初步研究结果表明，胎膜早破或早产的妇女在妊娠晚期和孕晚期母体血清甲胎蛋白水平升高；然而，需要更大的样本量。
