PREGNANCY WITH STILLBIRTH OF BOTH TWINS

Objective To identify and evaluate clinical characteristics in pregnan cy leading to stillbirth of both twins. Material and methods All 68 tw in deliveries in Sweden from 1973 to 1989 inclusive, where both twins were dead at birth, were identified by extracting information filed at the Medical Birth Registry (MBR), the National Board of Health and We lfare, Stockholm. Information in the MBR was used for analysis. A ques tionnaire was also distributed to each delivery unit to obtain informa tion on ultrasound scan made before either or both twins died, and typ e of placentation.Results The relative risk for like-sexed (M = 66) vi s-a-vis unlike-sexed fetuses (n = 2) to suffer intrauterine death was 12.6 (95% confidence limits 4.3, 37.5). The rate of like-sexed twins w as 97.1% versus 72.2% for the general twin population; monochorionic p lacentation was identified in 50.0% of these pregnancies. In only seve n was there a cause of death evident, including five pregnancies with lethal malformation. The median gestational duration was 33 weeks (ran ge 26 to 41). For the smaller twin in the pair there was an obvious tr end toward low birthweight and 16.1% were by definition small for gest ational age, whereas the larger twins seemed to have a normal birthwei ght distribution. The proportion of pregnancies with both twins stillb orn increased significantly with increasing discordance in weight (lin ear trend chi(2) = 4.5; P = 0.03). The interval between ultrasound exa mination showing two living fetuses and delivery was nine days or less in half the cases. Conclusion The major risk factor for fetal deaths seems to be a like-sexed pregnancy with a monochorionic placenta. Abou t half of pregnancies with available information had no more than nine days between an ultrasound examination, confirming two living fetuses , and birth. The great majority of these twins did not show evidence o f growth retardation, but birthweight discordance may be a risk factor for fetal death.