To investigate the related factors of preterm birth and neonatal outcomes in single pregnancy after in vitro fertilization and embryo transfer (IVF-ET).

A retrospective analysis was conducted in 250 pregnant women in the Sun Yat-sen Memorial Hospital from August 2013 to August 2015. The patients were divided into preterm birth of single pregnancy after IVF-ET (group A, 50 cases), preterm birth of single pregnancy after natural pregnancy (group B, 100 cases) and full-term birth of single pregnancy after IVF-ET (group C, 100 cases). By recording the incidence of gestational diabetes mellitus, gestational hypertension, premature rupture of membranes, placenta praevia or low-positioned placenta, as well as neonatal outcome, analyze the factors related to preterm delivery of single pregnancy after IVF-ET.

There were no significant differences in pregnancy complications, birth weight of premature infants and gestational weeks between group A and group B. The incidences of gestational hypertension in group A and group C were (14% and 3%), premature rupture of membranes (42% and 14%), placenta praevia or low-positioned placenta (12% and 2%), birth weight of newborn [(2225±622) g and (3231±482) g], 1 min Apgar score [(8.61±1.77) and (9.49±0.94)], 5 min Apgar score [(9.66±0.94) and (9.93±0.29)], and the differences between the two groups were statistically significant (P<0.05). Logistic regression analysis showed that gestational hypertension, premature rupture of membranes, placenta praevia or low-positioned placenta, cervical incompetence were associated with preterm birth of single pregnancy after IVF-ET. The incidences of cervical cerclage in pregnancies due to cervical incompetence were 22%, 9% and 4% in group A, group B and group C, respectively. There were significant difference between group A and group B, group C (P<0.05), respectively.

Gestational hypertension, premature rupture of membranes, placenta praevia or low-positioned placenta and cervical incompetence are high risk factors for preterm birth of single pregnancy after IVF-ET. The birth weight, Apgar score at 1 min and 5 min were all worse in preterm infants than in full term infants of single pregnancy after IVF-ET.