1. Introduction
The frequency of twin pregnancies is increasing worldwide due to increased maternal age and the use of assisted reproductive techniques, and adverse perinatal outcomes are higher in these pregnancies than in single pregnancies (1-3). Managing this increase in the rate of twin pregnancies is still a major problem. Also twin vaginal birth (VB) presents a unique clinical challenge for obstetricians. Although there is no consensus on the optimal method of birth in twin pregnancies, many researchers suggest that if the first twin has a vertex presentation, both twins are in the range of 1500–4000 g, and the second twin is not significantly larger than the first, VB is recommended (4). Both the American Congress of Obstetricians and Gynaecologists and the Society for Maternal Fetal Medicine recommend VB of twin gestations with the first twin in vertex presentation (5,6).
The reported cesarean rates of cesareans for the second twin range from 0.5% to 10% (7-9) and between 19.6 and 43.8% for both twins (10,11). These large rate ranges show that cesarean sections are associated with heterogeneous indications and some of these procedures are performed when VB is possible.
Many studies in the literature compare the effects of VB and cesarean birth (CB) on adverse pregnancy outcomes to clarify this issue. Although some studies show a reduction in the development of adverse pregnancies with CB (12,13), others report that adverse effects are not different between the two forms of birth (4,14). The differences in study design and the lack of quality randomized controlled trials are important reasons for this obvious debate.
The aim of this study is to evaluate the safety of VB by comparing the results of CB in twin pregnancies with the first twin in vertex presentation.