RESUMO
PURPOSE: Fetal sex is independently associated with pregnancy complications and impacts neonatal outcomes. Evidence suggests that females have an advantage over males, with a better outcome in the perinatal period. In addition, fetal outcome in twin gestations is also related to the intrauterine position of the fetus, such as the first, the presenting or second twin. It has been demonstrated that the neonatal outcome of the second fetus is worse than that of the first fetus. This study aimed to examine the influence of fetal sex on obstetric outcomes in twin pregnancies based on the location of the fetus in the uterus. METHODS: Retrospective study. Maternal and obstetric outcomes were compared among three groups: maleâmale, femaleâfemale, and maleâfemale groups. Comparisons of neonatal outcomes were performed among the four groups: male A-male B, male A-female B, female A-male B, and female A-female B. RESULTS: A total of 1073 twin gestations were included, comprising 288 maleâmale, 288 femaleâfemale, and 497 maleâfemale gestations. A greater percentage of neonates admitted to the NICU was observed for male fetuses than for female fetuses. Adverse composite neonatal outcome was more common in the maleâmale group than in the femaleâmale group and in the femaleâfemale group. CONCLUSION: Twin gestation with a first twin male tends to have worse neonatal outcomes than does twin gestation with a first twin female. The presence of a male co-twin increases the risk of adverse outcomes.