Disturbed intrauterine growth in twins: etiological aspects

Factors presumed to influence intrauterine growth were analyzed among 192 twin pairs. Mean birthweight was considerably reduced compared to single pregnancies, and a high proportion of twins were growth retarded (12.4%). One fifth of the twin pairs presented an intrapair birthweight difference exceeding 20%. DZ twins were slightly heavier than the MZ, while dichorionic twins had a somewhat higher birthweight than the monochorionic. The intrapair weight differences were greater in twins with fused dichorionic placentae than in those with separate ones. The umbilical cord insertion seemed to influence intrauterine growth. Fetuses with velamentously or marginally inserted cords presented more frequently retarded growth than twins with centrally inserted umbilical cords. Though a total of 13 cases of twin transfusion syndromes were observed, these were not characterized by great intrapair weight differences.