[A rare increase in the incidence of Siamese twin deliveries (author's transl)].

Between 1964--1978 4 pairs of siamese twin were born among 28,039 deliveries. The incidence was 1 : 7009. Three pairs of siamese twins were delivered vaginally and died during delivery. The fourth patient was delivered by Caesarean section and the infants died a few hours following delivery. Autopsies showed that none of the cases were viable. The problems of the diagnosis and obstetric management of siamese twins are discussed. The antenatal diagnosis is difficult out should ideally be obtained. Vaginal deliveries are difficult and dangerous for the mothers. Caesarean section is the perferred method of delivery. The four personal cases are reviewed.