Purpose of review: To examine the existing literature in regards to the relationship between assisted reproductive technologies (ART) and low birth weight (LBW).
Recent findings: In 2017, Martin et al. reported on the incidence of low birth weight in relation to the number of embryos transferred, and showed that incidence of low birth weight in singletons correlates with number of embryos transferred. Meanwhile, several studies have shown increased weight of singletons born after frozen embryo transfers compared with fresh embryo transfers. A recent study published by Sekhon et al., among others, disputes these findings, and claims that frozen and fresh embryo transfers result in comparable birth weights. It is also noteworthy that Mass et al., in 2016, analyzed how birth weight as a result of assisted reproductive technologies has evolved over the years, and concluded that birth weight has not changed significantly over a long period of time.
Summary: Newborns conceived via assisted reproductive technologies are three times more likely to have low birth weight. Although multiple gestation and its associated prematurity are the main risk factors for low birth weight in ART-conceived pregnancies, some of the other processes specific to assisted reproduction also impact perinatal outcomes. Options, such as fresh or frozen embryo transfers, the number of embryos transferred, or endometrial preparation may all importantly affect birth weight and prematurity of ART-conceived newborns.