Predicting the chances of a live birth after one or more complete cycles of in vitro fertilisation: population based study of linked cycle data from 113 873 women

Abstract

Objective: To develop a prediction model to estimate the chances of a live birth over multiple complete cycles of in vitro fertilisation (IVF) based on a couple's specific characteristics and treatment information.

Design: Population based cohort study.

Setting: All licensed IVF clinics in the UK. National data from the Human Fertilisation and Embryology Authority register.

Participants: All 253 417 women who started IVF (including intracytoplasmic sperm injection) treatment in the UK from 1999 to 2008 using their own eggs and partner's sperm.

Main outcome measure: Two clinical prediction models were developed to estimate the individualised cumulative chance of a first live birth over a maximum of six complete cycles of IVF-one model using information available before starting treatment and the other based on additional information collected during the first IVF attempt. A complete cycle is defined as all fresh and frozen-thawed embryo transfers arising from one episode of ovarian stimulation.

Results: After exclusions, 113 873 women with 184 269 complete cycles were included, of whom 33 154 (29.1%) had a live birth after their first complete cycle and 48 925 (43.0%) after six complete cycles. Key pretreatment predictors of live birth were the woman's age (31 v 37 years; adjusted odds ratio 1.66, 95% confidence interval 1.62 to 1.71) and duration of infertility (3 v 6 years; 1.09, 1.08 to 1.10). Post-treatment predictors included number of eggs collected (13 v 5 eggs; 1.29, 1.27 to 1.32), cryopreservation of embryos (1.91, 1.86 to 1.96), the woman's age (1.53, 1.49 to 1.58), and stage of embryos transferred (eg, double blastocyst v double cleavage; 1.79, 1.67 to 1.91). Pretreatment, a 30 year old woman with two years of unexplained primary infertility has a 46% chance of having a live birth from the first complete cycle of IVF and a 79% chance over three complete cycles. If she then has five eggs collected in her first complete cycle followed by a single cleavage stage embryo transfer (with no embryos left for freezing) her chances change to 28% and 56%, respectively.

Conclusions: This study provides an individualised estimate of a couple's cumulative chances of having a baby over a complete package of IVF both before treatment and after the first fresh embryo transfer. This novel resource may help couples plan their treatment and prepare emotionally and financially for their IVF journey.

Fig 1 Number of women having a live birth, not having a live birth but continuing in vitro fertilisation (IVF), or not having a live birth and not continuing IVF (during follow-up) over six complete cycles of IVF

Fig 2 Plots showing unadjusted (univariable) relations between the following continuous baseline variables and a live birth in the first complete cycle of in vitro fertilisation. (A) Woman’s age (years); (B) duration of infertility (years); (C) year of first complete cycle, and (D) number of eggs retrieved in first complete cycle. Each panel depicts the probability of live birth (solid curve) with 95% confidence bands as a function of the baseline variable. The degrees of freedom (df) associated with the χ2 statistic in each case depend on the complexity of the relation between the variable and the log odds of live birth. Where df >1, the relation was non-linear and characterised by restricted cubic spline functions. Where df=1, the relation was linear even though the plot shown here, which reflects live birth (rather than the log odds), exhibits a non-linear relation

Fig 3 Example of pretreatment model predicting cumulative probability of live birth over six complete cycles of in vitro fertilisation (IVF) for women aged 30 or 40 with two or five years of primary infertility who have: (A) male factor infertility and had treatment by intracytoplasmic sperm injection; (B) unexplained infertility and underwent IVF

Fig 4 Example of post-treatment model predicting cumulative probability of live birth over six complete cycles of in vitro fertilisation (IVF) for different patient and treatment characteristics (these patients have all had primary infertility for two years)