A women's birth cohort effect on malformation rates.

A relatively sudden increase in prevalence at birth of gastroschisis was seen in Sweden at the beginning of the 1970s. Case-control studies, looking for a teratogenic factor, have proved negative. This paper presents a hypothesis suggesting that the women's birth cohort has an effect: women born in 1953-5 have an increased probability of having this type of malformed infants. A computer simulation is made indicating that the actually recorded facts can, at least in part, be explained by the hypothesis.