Congenital malformations and season of birth: A brief review

Seasonal cycles in the births of infants with certain congenital malformations have been reported by several investigators. There have been conflicting reports regarding months of greatest frequency of each group of defects. Congenital malformations of the cardiovascular system have been noted to vary with seasonal infections of mothers with rubella. Variations in other maternal infections during early pregnancy and the drugs given in treatment may be significant. Sex differences have been noted, with congenital malformations of the musculoskeletal system more common in females. Central nervous system malformations generally show a winter excess in frequency. Some cardiovascular malformations seem to have a summer or autumn peak and be more frequent in female infants.