PREDICTING PROBABILITIES OF PREGNANCY AND MULTIPLE GESTATION FROM IN-VITRO FERTILIZATION - A NEW MODEL

Objective: To develop a statistical model that adjusts for variation b etween patients and adequately predicts the observed distribution of p regnancies among singletons and multiple gestations of various orders. Methods: All in vitro fertilization (IVF) cycles from the inception o f the IVF program at Women and Infants' Hospital on May 26, 1988, unti l December 31, 1993, were evaluated using logistic regression in selec ted subsets. Results: A new cycle-one specific model uses three differ ent probabilities: P1, the probability of pregnancy (predicted by age and total embryo score); P2\P1, the conditional probability of finding a second implantation in those who had become pregnant with at least one (predicted by total embryo score); and P3\P2, the conditional prob ability of finding a third implantation in those who had become pregna nt with at least two (with no significant predictors). This is the fir st model to use these three adjusted probabilities. Conclusion: P1 inc reases with increasing total embryo score but decreases with increasin g age. P2\P1 increases with increasing total embryo score but does not depend on age. Embryo scoring is useful because the total embryo scor e is a better predictor of P1 and F2\P1 than the number of embryos alo ne. By using patient-specific information (age and total embryo score) and cycle-specific tables, an estimate of the probability of pregnanc y and multiple gestation can be provided before embryo transfer. (C) 1 998 by The American College of Obstetricians and Gynecologists.