Predicting ongoing pregnancy chances after IVF and ICSI: a national prospective study.

BACKGROUND The Dutch IVF guideline suggests triage of patients for IVF based on diagnostic category, duration of infertility and female age. There is no evidence for the effectiveness of these criteria. We evaluated the predictive value of patient characteristics that are used in the Dutch IVF guideline and developed a model that predicts the IVF ongoing pregnancy chance within 12 months. METHODS In a national prospective cohort study, pregnancy chances after IVF and ICSI treatment were assessed. Couples eligible for IVF or ICSI were followed during 12 months, using the databases of 11 IVF centres and 20 transport IVF clinics. Kaplan-Meier analysis was performed to estimate the cumulative probability of an ongoing pregnancy, and Cox regression was used for assessing the effects of predictors of pregnancy. RESULTS 4928 couples starting IVF/ICSI treatment were prospectively followed. On average, couples had 1.8 cycles in 12 months for both IVF and ICSI. The 1-year probability of ongoing pregnancy was 44.8% (95% CI 42.1-47.5%). ICSI for severe oligospermia had a significantly higher ongoing pregnancy rate than IVF indicated treatments, with a multivariate Hazard ratio (HR) of 1.22 (95% CI 1.07-1.39). The success rates were comparable for all diagnostic categories of IVF. The highest success rate is at age 30, with a slight decline towards younger women and women up to 35 and a sharp drop after 35. Primary subfertility with a HR of 0.90 (95% CI 0.83-0.99) and duration of subfertility with a HR of 0.97 (95% CI 0.95-0.99) per year significantly affected the pregnancy chance. CONCLUSIONS The most important predictors of the pregnancy chance after IVF and ICSI are women's age and ICSI. The diagnostic category is of no consequence. Duration of subfertility and pregnancy history are of limited prognostic value.