Pregnancy chances on an IVF/ICSI waiting list: a national prospective cohort study

BACKGROUND: The effectiveness of IVF over expectant management has been proven only for bilateral tubal occlusion. We aimed to estimate the chance of pregnancy without treatment for IVF patients, using data on the waiting period before the start of IVF. METHODS: A prospective cohort study included all couples eligible for IVF or ICSI treatment, registered in a national waiting list in The Netherlands. The cumulative probability of treatment-free ongoing pregnancy on the IVF waiting list was assessed and the predictive effect of female age, duration of infertility, primary or secondary infertility and diagnostic category was estimated using Cox regression. RESULTS: We included 5962 couples on the waiting list. The cumulative probability of treatment-free ongoing pregnancy was 9% at 12 months. In multivariable Cox regression, hazard ratios were: 0.95 (P < 0.001) per year of the woman's age, 0.85 (P < 0.001) per year of duration of infertility, 0.71 (P = 0.005) for primary versus secondary infertility. Diagnostic category showed hazard ratios of 0.7, 1.6, 1.2, 1.7 and 2.6 for endometriosis, male factor, hormonal, immunological and unexplained infertility, respectively, compared with 'tubal infertility' (P < 0.001). The 12-months predicted probabilities ranged from 0% to 25%. CONCLUSIONS: The chance of an ongoing pregnancy without treatment while waiting for an IVF or ICSI is below 10% but may be as high as 25% within 1 year for selected patient groups. Timing of IVF should take predictive factors into consideration.