Waldenström U, Axelsson O, Nilsson S
Department of Obstetrics and Gynecology, Falu Hospital, Falun, Sweden.
Ultrasound Obstet Gynecol. 1993 Jan 1;3(1):23-5. doi: 10.1046/j.1469-0705.1993.03010023.x.
A total of 358 women succeeded in conceiving in the first cycle after stopping oral contraception. The estimated day of delivery was calculated from both an ultrasonographically measured fetal biparietal diameter, in the second trimester, and from the date of the withdrawal bleed. According to the biparietal diameter measurement, the estimated day of delivery was postponed more than 1 week in 138 cases (38.5%). For 304 women who delivered after the spontaneous onset of labor, the biparietal diameter estimate gave the best prediction of the day of delivery in 175 cases (57.6%), the date of the withdrawal bleed gave the best estimate in 91 (29.9%) (p < 0.001) and they were equally good in 38 (12.5%). The estimated day of delivery using a biparietal diameter measurement was within +/- 14 days of the day of delivery for 267 of these 304 women (87.8%). The corresponding figure for the withdrawal bleed date was 218 (71.7%) (p </= 0.001). According to the withdrawal bleed date estimate, 68 women (22.4%) delivered beyond the estimated 42 weeks, compared to only 2.6% according to the biparietal diameter estimate. The median length of a pregnancy from the first day of the withdrawal bleed was 286 days and from the biparietal diameter was 281 days.
共有358名女性在停止口服避孕药后的第一个周期成功受孕。分娩预估日期是根据孕中期超声测量的胎儿双顶径以及撤药性出血日期来计算的。根据双顶径测量结果，138例（38.5%）的分娩预估日期推迟了1周以上。对于304名自然发动分娩的女性，双顶径估计在175例（57.6%）中对分娩日期的预测最为准确，撤药性出血日期在91例（29.9%）中预测最佳（p<0.001），两者同样准确的有38例（12.5%）。在这304名女性中，有267名（87.8%）通过双顶径测量得出的分娩预估日期与实际分娩日期相差在±14天内。撤药性出血日期的相应数字为218名（71.7%）（p≤0.001）。根据撤药性出血日期估计，68名女性（22.4%）在预估的42周后分娩，而根据双顶径估计这一比例仅为2.6%。从撤药性出血第一天算起的孕期中位数为286天，从双顶径算起为281天。
