Deliveries and children born after in-vitro fertilisation in Sweden 1982-95: a retrospective cohort study

Background In-vitro fertilisation is an effective treatment for infertility , but there is concern about the health of children. We investigated, in a retrospective registry study, malformations, cancers, and deaths In the com plete Swedish in-vitro-fertilisation birth cohort compared with the general population. Methods We collected data from all in-vitro-fertilisation clinics in Sweden and compared the obstetric outcomes of babies (n=5856) born between 1982 a nd 1995 with all babies born in the general population (n=1 505 724) during the same period, according to data from the Swedish Medical Birth Registry and the Registry of Congenital Malformations. We investigated the incidenc e of childhood cancer through the Swedish Cancer Registry. Data were strati fied for maternal age, parity, previous subfertility, year of birth, and mu ltiple of pregnancies. Findings Multiple births occurred in 27% of pregnancies compared with 1% in the control group. In the in-vitro-fertilisation group, more babies were b orn preterm (<37 weeks) than controls (30.3 vs 6.3%) and more had low birth weights (<2500 g, 27.4 vs 4.6%). The perinatal mortality was 1.9% in the in -vitro fertilisation group and 11% in the controls. For in-vitro-fertilisat ion singletons, the risk ratios, adjusted for year of birth, for very prete rm birth (<32 weeks) and very low birthweight (<1500 g) were 3.54 (95% CI 2 .90-4.32) and 4.39 (3.62-5.32), respectively. Malformations occurred in 5.4 % of all babies in the in-vitro fertilisation group (1.39 [1.25-1.54]), and the rates of neural-tube defects and oesophageal atresia were higher than those in the controls. There was no increase in childhood cancer in the in- vitro-fertilisation group. Interpretation A high frequency of multiple births and maternal characteris tics were the main factors that led to adverse outcomes, and not the in-vit ro-fertilisation technique itself. The clinical practice of in-vitro-fertil isation needs to be changed to lower the rate of multiple pregnancy.