Objective: To investigate the perinatal maternal and fetal adverse outcomes of cesarean section in the different duration of the second stage of labor. Methods: A retrospective cohort study was conducted on the clinical data of 154 pregnant women with singleton head pregnancy who underwent cesarean section at different times of the second stage of labor due to maternal and fetal factors in the First Affiliated Hospital of Nanjing Medical University from January 1, 2019 to December 31, 2021. According to the duration of the second stage of labor, they were divided into <2 h group (54 cases), 2-<3 h group (61 cases), and ≥3 h group (39 cases). The general data of pregnant women and neonates, preoperative maternal and neonatal conditions related to labor stages, surgical indications, surgical procedures, and perioperative maternal and neonatal adverse outcomes were compared among the three groups. Results: (1) General Information: there were no significant differences in maternal age, gravidity and parity, proportion of primipara, gestational age at delivery, body mass index before delivery, pregnancy complications, labor analgesia rate and the duration of the first stage of labor among the three groups (all P>0.05). The differences of the gender composition, birth weight and incidence of macrosomia of the three groups were also not statistically significant (all P>0.05). (2) Maternal and fetal status and surgical indications: the incidence of intrapartum fever and type Ⅱ and Ⅲ fetal heart rate monitoring in the <2 h group were higher than those in the 2-<3 h group and the ≥3 h group, and the preoperative fetal head position in the ≥3 h group was lower than that in the 2-<3 h group, with statistically significant differences (all P<0.05). The proportion of cesarean section due to "fetal distress" was 40.7% (22/54) in the <2 h group, which was higher than that in the 2-<3 h group (4.9%, 3/61) and the ≥3 h group (2.6%, 1/39). The proportions of surgical indication of "relative cephalo-pelvic disproportion" were 98.4% (60/61) and 94.9% (37/39) in the 2-<3 h group and ≥3 h group, respectively, and the surgical indication of "fetal head descent arrest" were 41.0% (25/61) and 59.0% (23/39), respectively. Compared with <2 h group [63.0% (34/54), 13.0% (7/54)], the differences were statistically significant (all P<0.05). There were no significant difference in surgical indications between 2-<3 h group and ≥3 h group (all P>0.05). (3) Intraoperative conditions and perioperative complications of cesarean section: the puerperal morbidity rate of <2 h group was 37.0% (20/54), which was higher than those of 2-<3 h group (18.0%, 11/61) and ≥3 h group (7.7%, 3/39), the difference was statistically significant (P<0.05). There were no significant differences in operation time, intraoperative blood loss, incidence of fetal head inlay, uterine incision tear, modified B-Lynch suture for uterine atony, postpartum hemorrhage, perioperative blood transfusion, preoperative hemoglobin (Hb) level, perioperative Hb change, and postoperative hospital stay among the three groups (all P>0.05). (4) Adverse neonatal outcomes: non-hemolytic neonatal hyperbilirubinemia in ≥3 h group was 35.9% (14/39), which was significantly higher than that in <2 h group (13.0%, 7/54; P<0.05). Among the neonates admitted to neonatal intensive care unit (NICU) within 1 week after birth, the proportion of neonates admitted to NICU due to neonatal hyperbilirubinemia in ≥3 h group (15/19) was significantly higher than that in <2 h group (9/17) and 2-<3 h group (10/19), and the differences were statistically significant (all P<0.05). However, there was no significant difference between the <2 h group and the 2-<3 h group (P>0.05). There was no perinatal death in the three groups. Conclusions: The rate of puerperal morbidity is higher in patients who were transferred to cesarean section within 2 hours of the second stage of labor. In the early stage of the second stage of labor, the monitoring of fetal heart rate and amniotic fluid characteristics should be strengthened, especially the presence or absence of prenatal fever. In good maternal and neonatal conditions, conversion to cesarean section after 2 hours of the second stage of labor does not significantly increase the incidence of serious adverse maternal and neonatal outcomes. For the second stage of labor more than 3 hours before cesarean section, it is necessary to strengthen the monitoring of neonatal bilirubin.