This retrospective observational study reports on the higher incidence of cardiac defects in newborns after in vitro
fertilization (IVF) at a single center. The incidence of major congenital malformations of 379 children born between
1985 and 1989 (group A) following IVF after culture in medium containing human serum was compared to that of 441
children born between 1993 and 1997 (group B) after IVF using commercially produced media in which serum is substituted
by synthetic serum replacement/ human serum albumin. In group A, major birth defects were noticed in 4.2% of
cases with 2.9% clinically apparent congenital heart defects (CHD) at birth compared to an incidence of major birth defects
of 0.7% in group B with no clinically apparent CHD (P < 0.001). Components in the in vitro culture system containing
serum are likely related to the congenital malformations observed in this study.