Harlap S, Shahar S, Baras M
Am J Hum Genet. 1985 Nov;37(6):1206-15.
Multiple births were studied in a sample of orthodox Jewesses for whom an estimate could be made of the day of ovulation and the earliest possible day of conception. The overall rate of twinning was 14.5/1,000 deliveries, and of triplets, 0.40/1,000. Twinning rates varied significantly from 11.4 in the 5,976 "early" conceptions (day -1 or earlier relative to the estimated day of ovulation) to 26.9 in the 1,498 "late" conceptions (day 0 or later). Triplets varied significantly from 0 to 2.01 in early and late conceptions, respectively, and unlike-sexed multiple sets, 2.8 and 12.8, respectively. The excess of multiple births in late conceptions was seen within different ages and origin groups, in women with different menstrual characteristics, and in those with and without treatment for anovulation. While the excess of unlike-sexed sets seems to lead to the conclusion that late conceptions are associated with dizygosity, polar body twinning and uniovular dispermatic twinning should also be considered.
对一群遵守教规的犹太女性样本进行了多胞胎研究，这些女性的排卵日和最早受孕日是可以估算的。双胞胎的总体发生率为每1000例分娩中有14.5例，三胞胎为每1000例中有0.40例。双胞胎发生率在5976例“早期”受孕（相对于估计排卵日的-1天或更早）中为11.4，在1498例“晚期”受孕（0天或更晚）中为26.9，差异显著。三胞胎在早期和晚期受孕中的发生率分别从0到2.01有显著差异，而异性多胞胎在早期和晚期受孕中的发生率分别为2.8和12.8。在不同年龄和出身群体、具有不同月经特征的女性以及有无无排卵治疗的女性中，均可见晚期受孕中多胞胎的发生率过高。虽然异性多胞胎的发生率过高似乎得出晚期受孕与双合子性有关的结论，但也应考虑极体孪生和单卵双精孪生。
