Contribution of cryopreservation in a mandatory SET policy: analysis of 5 years of application of law in an academic IVF center

To analyse treatment outcomes after SET law enforcement and to evaluate the contribution of cryopreservation in a SET policy.Embryo transfer cycles performed after the law enforcement (SET period) was retrospectively compared to the cycles performed before the law enforcement (DET period).Pregnancy and delivery rates after fresh transfer of SET and DET periods were comparable (31.7% versus 33.3% and 24.5% versus 26.2%, respectively, NS). Overall twin delivery rate is significantly decreased after the law enforcement (11.3% versus 22.4%, p 0.001) but not in patients aged 36 to 39 years (20.3% versus 24%, NS). Frozen-thawed embryo cycles allowed similar cumulative pregnancy rate (30.6%, NS). Taking into account all frozen embryos still to be transferred, SET period offers a better overall pregnancy rate than the DET period (36.1% versus 32.3%, p 0.01).The Belgian law allowed a dramatic reduction of twin deliveries especially for patients under 39 years. Cryopreservation maintains a similar cumulative pregnancy rate.