Children born after assisted fertilization have an increased rate of major congenital anomalies.

To study the occurrence of major congenital anomalies (CAs) among children born after IVF (IVF, microinjections, and frozen embryo transfers) and after ovulation inductions with or without insemination (other assisted reproductive technologies [ART]). Register-based study. Data regarding CAs were obtained from the Register of Congenital Malformations. Children from IVF (n = 4,559), children from other ART (n = 4,467), and controls (n = 27,078, a random sample of naturally conceived children) from the Medical Birth Register. In vitro fertilization and other ART treatment in ordinary practice. Rate of major CAs. Children from IVF and other ART were compared with control children, both overall and by plurality, controlling for confounding factors by logistic regression. For IVF children, the adjusted odds ratio (OR) was 1.3 (95% confidence interval [CI], 1.1-1.6). Stratifying by gender and plurality showed that the risk was only increased for boys, and the risk was decreased for multiple IVF girls (OR = 0.5, 95% CI 0.2-0.9). The crude OR of major CA for other ART children was 1.3 (95% CI 1.1-1.5), but adjusted differences by gender and plurality were statistically insignificant. In vitro fertilization was associated with an increased risk for major CAs among singleton boys and a decreased risk among multiple girls. The risk after other ART was only slightly increased.