Of all the available therapies, in adequately selected patients, bariatric surgery (BS) is the most efective treatment for severe obesity and its complications. Despite the numerous benefits of BS, even in reproductive performance, women who have undergone BS have higher rates of small-for-gestational age (SGA) fetuses and preterm births than non-intervened women with the same body mass index (BMI). The mechanisms involved are not known, but nutritional defciencies, common after BS, have been identifed as one of the factors that could contribute to these pregnancy complications.