Objectives: Multiple pregnancies are known to be associated with adverse maternal and perinatal complications. How­ever, data regarding the outcomes of spontaneously reduced twin pregnancies are limited. In the current study we aimed to evaluate the consequences of the vanishing twin syndrome (VTS) in dichorionic diamniotic twin pregnancies for both mother and baby in our perinatal center.

Material and methods: A total of 711 pregnancies were included into the study. 51 cases of vanishing twin syndrome constituted Group 1, 235 cases of normal twins constituted Group 2, and 425 singleton pregnancies formed Group 3. The pregnancies that had multifetal reduction and monochorionic twinning were excluded from both study group and twin control group. The collected data were as follows: age, gravidity, parity, gestational week at birth, delivery route, birth weight, obstetric complications, and maternal and perinatal outcomes.

Results: No significant difference was observed between the groups regarding mean maternal age (p > 0.05). Mean birth weight, gestational age at birth and preterm birth ratio were significantly lower in the Group 2 when compared with Group 1 and Group 3 (all p < 0.001). Adverse perinatal outcomes including very low birth weight (VLBV) and low Apgar scores were more common in Group 1 (p < 0.05), but no significant difference was found between the groups in terms of neona­tal intensive care unit admission and perinatal mortality ratios (p > 0.05). Obstetric complications such as preeclampsia, gestational diabetes and intrauterine growth restriction were significantly higher in Group 2 than in Group 1 and Group 3 (all p < 0.05). However, severe maternal morbidities were similar among three groups (p = 0.141).

Conclusions: VTS is seems to be associated with VLBV and low Apgar scores. However, the incidence of severe maternal and perinatal morbidity and mortality in pregnancies with VTS is similar to other pregnancies.