Pregnancy-induced hypertension in twin pregnancy.

A prospective study of 54 primigravid twin pregnancies in Durban showed that pregnancy-induced hypertension occurred in 37%. This was more than twice the expected rate for singleton pregnancies in this Black African population. The babies born in the group of patients with pregnancy-induced hypertension were significantly lighter and had a higher rate of fetal growth retardation than the babies born in a normotensive control group of patients matched for age and parity. Monozygotic twins, identified by HLA typing, occurred significantly more often in the group with pregnancy-induced hypertension than in the control group. A possible immunological explanation for this finding is presented.