Time to pregnancy: results of the German prospective study and impact on the management of infertility.
Level 3 - non-randomized controlled study
Prospective observational cohort study
PubMed 12923157 · doi:10.1093/humrep/deg366
What was done
A prospective cohort study observed 346 women who used natural family planning (NFP) methods to time intercourse from their first cycle trying to conceive. Cumulative probabilities of conception (CPC) were estimated using Kaplan-Meier survival curves for the total cohort and separately for the subset of couples who achieved pregnancy.
What was found
Of 346 women, 310 conceived and 36 (10.4%) did not. For the total group (n = 340), estimated cumulative probabilities of conception were 38% at 1 cycle, 68% at 3 cycles, 81% at 6 cycles, and 92% at 12 cycles. For the subgroup who ultimately conceived (n = 304), rates were 42% at 1 cycle, 75% at 3 cycles, 88% at 6 cycles, and 98% at 12 cycles. Age had a statistically smaller impact on time to conception in the subgroup of truly fertile couples than in the total cohort.
Why it matters
This study provides prospective benchmarks for spontaneous conception rates under optimal timing conditions, suggesting that infertility workup may be warranted after six failed cycles rather than waiting a full year.
Limits
The study was restricted to German NFP users, who may have higher motivation and compliance than the general population. The abstract does not provide specific age brackets, male factor fertility data, or information on coexisting medical conditions.
Cited by
- partial Among fertile couples having regular intercourse 3 to 4 times a week, 50% conceive within the first 6 months and 90% conceive within the first year.