Hyperemesis during pregnancy and delivery outcome: a registry study.

Delivery outcome was studied in 3068 pregnancies with the diagnosis of hyperemesis in the Swedish Medical Birth Registry for the years 1973-1981. This diagnosis was present in a little over 3 per thousand deliveries in the registry but its prevalence varied enormously between different hospitals, from over 1% to practically nil. The diagnosis was over-represented at low maternal age and first parity and when the infant was a girl. Twinning occurred at a significantly increased rate. Gestational length was somewhat shorter and birthweight was lower than expected but this had no effect on perinatal survival. Congenital malformations were present slightly more often than expected and this was due to three diagnoses: undescended testicles, hip dysplasia, and Down syndrome. Possible explanations for this excess are discussed.