Gnoth C, Godehardt D, Godehardt E, Frank-Herrmann P, Freundl G
Department of Reproductive Medicine and Gynaecological Endocrinology, Staedtische Kliniken Duesseldorf gGmbH, Frauenklinik Benrath, Germany.
Hum Reprod. 2003 Sep;18(9):1959-66. doi: 10.1093/humrep/deg366.
The likelihood of spontaneous conception in subsequent cycles is important for a balanced management of infertility. Previous studies on time to pregnancy are mostly retrospective and biased because of exclusion of truly infertile couples. The study aim was to present a non-parametric estimation of cumulative probabilities of conception (CPC) in natural family planning (NFP) users illustrating an ideal of human fertility potential.
A total of 346 women was observed who used NFP methods to conceive from their first cycle onwards. The couples practising NFP make optimal use of their fertility potential by timed intercourse. The CPC were estimated for the total group and for couples who finally conceived by calculating Kaplan-Meier survival rates.
A total of 310 pregnancies occurred among the 346 women; the remaining 36 women (10.4%) did not conceive. Estimated CPC for the total group (n = 340 women) at one, three, six and 12 cycle(s) were 38, 68, 81 and 92% respectively. For those who finally conceived (truly fertile couples, n = 304 women), the respective pregnancy rates were 42, 75, 88 and 98% respectively. Although the numbers of couples in both groups were similar, the impact of age on time to conception, as judged by the Wilcoxon test, was less in the truly fertile than in the total group.
Most couples conceive within six cycles with timed intercourse. Thereafter, every second couple is probably either subfertile or infertile. CPC decline with age because heterogeneity in fecundity increases. In the subgroup of truly fertile couples, an age-dependent decline in CPC is statistically less obvious because of high homogeneity, even with advancing age.
后续周期自然受孕的可能性对于不孕症的平衡管理很重要。以往关于受孕时间的研究大多是回顾性的，且由于排除了真正不孕的夫妇而存在偏差。本研究的目的是对自然计划生育（NFP）使用者受孕的累积概率（CPC）进行非参数估计，以说明人类生育潜力的理想情况。
共观察了346名从第一个周期开始使用NFP方法受孕的女性。采用NFP的夫妇通过定时性交来最佳利用其生育潜力。通过计算Kaplan-Meier生存率来估计总人群以及最终受孕夫妇的CPC。
346名女性中总共发生了310次妊娠；其余36名女性（10.4%）未受孕。总人群（n = 340名女性）在第1、3、6和12个周期的估计CPC分别为38%、68%、81%和92%。对于最终受孕的女性（真正有生育能力的夫妇，n = 304名女性），相应的妊娠率分别为42%、75%、88%和98%。尽管两组中的夫妇数量相似，但通过Wilcoxon检验判断，年龄对受孕时间的影响在真正有生育能力的夫妇中比在总人群中要小。
大多数夫妇通过定时性交在六个周期内受孕。此后，每两对夫妇中可能就有一对要么是亚生育能力要么是不育。CPC随年龄下降，因为生育力的异质性增加。在真正有生育能力的夫妇亚组中，由于同质性高，即使年龄增长，CPC随年龄的下降在统计学上也不太明显。
