Department of Gynaecological Endocrinology and Fertility Disorders, University of Heidelberg, Vossstrasse 9, 69115 Heidelberg, Germany. petra.frank-herrmann@med.uni-heidelberg.deROR
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.
Methods
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.
Results
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.
Conclusions
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.
time to pregnancy natural family planning prospective study, cumulative probability conception timed intercourse NFP, Gnoth Freundl time to pregnancy German study, subfertility infertility definition time to conception cycles, natural family planning fertility awareness conception rates, Kaplan-Meier survival analysis time to pregnancy, age effect fecundity time to conception, spontaneous conception probability infertility management, timed intercourse fertile window conception rate, human fertility potential natural conception six cycles, fecundability decline age heterogeneity conception
PMID 12923157 12923157 DOI 10.1093/humrep/deg366 10.1093/humrep/deg366
Cite this article
Gnoth, C., Godehardt, D., Godehardt, E., Frank-Herrmann, P., & Freundl, G. (2003). Time to pregnancy: results of the German prospective study and impact on the management of infertility. Human reproduction (Oxford, England), 18(9), 1959-1966. https://doi.org/10.1093/humrep/deg366
Gnoth C, Godehardt D, Godehardt E, Frank-Herrmann P, Freundl G. Time to pregnancy: results of the German prospective study and impact on the management of infertility. Hum Reprod. 2003;18(9):1959-1966. doi:10.1093/humrep/deg366
Gnoth, C., et al. "Time to pregnancy: results of the German prospective study and impact on the management of infertility." Human reproduction (Oxford, England), vol. 18, no. 9, 2003, pp. 1959-1966.
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