Objective: To estimate the likelihood of live birth and the impact of prognostic factors among untreated infertile couples.
Design: Cohort follow-up study.
Setting: Eleven infertility clinics in academic medical centers.
Patients: Two thousand one hundred ninety-eight couples with infertility of > 1 year in duration. Untreated months of observations on 873 untreated couples (18,364 months) were combined with observations before the first treatment among 1,325 treated couples (9,761 months).
Interventions: Diagnostic tests as indicated.
Main outcome measures: Time to conception for live birth; effect of baseline characteristics estimated by means of proportional hazards analysis.
Results: There were 263 live birth conceptions during 28,125 months of untreated observations. The cumulative rate of conceptions leading to live birth was 14.3% at 12 months. The relevant prognostic factors were pregnancy history, duration of infertility, female partner's age, male defect, endometriosis, and tubal disease. A prediction score based on these factors would be accurate in approximately 62% of cases.
Conclusions: The estimation of live birth among untreated infertile couples is sufficiently accurate to be useful in the clinical management of infertility and in the planning of clinical trials.