Objective To investigate the effects of premature rupture of membranes (PPROM) or oligohydramnios on in-hospital outcomes of preterm infants with gestational age<32 weeks. Methods The clinical data of preterm infants with gestational age<32 weeks who were hospitalized from January 2019 to December 2022 were retrospectively analyzed. The patients were divided into PPROM group and normal group according to the presence or absence of PPROM. PPROM patients combined with oligohydramnios were further included in the oligohydramnios group. The clinical features were compared among the groups. Multivariate logistic regression was used to analyze the effects of PPROM and oligohydramnios on in-hospital outcomes of preterm infants<32 weeks of gestational age. Results A total of 195 preterm infants were included, 83 in the PPROM group, 22 in the oligohydramnios group. There were 112 neonates in the normal group. The median gestational age of PPROM was 29.5 (28.5-30.5) weeks, and the median duration was 48.0 (13.8-85.8) hours. Multivariate logistic regression analysis showed that oligohydramnios was an independent risk factor for death before discharge, hemodynamically significant patent ductus arteriosus (hsPDA) and persistent pulmonary hypertension (PPHN) (P<0.05). The PPROM duration≥168h significantly increased the incidence of PPHN (P<0.05). Compared with the group with only PPROM, the group with both PPROM and oligohydramnios had a longer duration of PPROM, a smaller gestational age at the time of PPROM, and a smaller gestational age at birth, with statistically significant differences (P<0.05). Conclusions The effects of PPROM and oligohydramnios on neonatal prognosis are different. There was no significant correlation between PPROM and premature death and neonatal related diseases. However, PPROM with long duration and oligohydramnios is potentially dangerous for premature infants. Oligohydramnios is closely related to premature death, PPHN and other adverse outcomes.