PHGDH and hydronephrosis: In SERa + cycles, three newborns had malformations, one with hydronephrosis originating from the group exclusively derived from SERa + embryo transfer, one with persistent left superior vena cava and one with congenital heart disease originating from the group of mixed SERa + and SERa- embryo transfer, the other 156 newborns were healthy babies.