Analysis of risk factors for very early preterm and early preterm birth in twins following in vitro fertilization and intracytoplasmic sperm injection-assisted pregnancy: A retrospective study

To investigate the risk factors influencing very early preterm and early preterm births in twin pregnancies after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). This retrospective study analyzed 2042 twin pregnancies that underwent embryo transfer via IVF/ICSI at the Reproductive Center of Sir Run Run Shaw Hospital between January 2019 and December 2022. Spontaneous very early, early preterm, and provider-initiated preterm births were examined separately. Based on gestational age, participants were categorized into three groups: very early preterm birth (