·To explore the pregnancy complications and adverse pregnancy outcomes, and summarize the pregnancy characteristics of elderly primiparas.

·A total of 300 elderly primiparas who delivered in Shunde Women's and Children's Hospital Affiliated to Guangdong Medical University from January 2017 to December 2018 were selected to form the elderly primipara group, and a total of 2 138 elderly multiparae who gave birth to their second child in the same period were selected to form the elderly multipara group. A total of 2 088 primiparas at the appropriate age were randomly selected according to the discharge date to form the appropriate age primipara group, and 1 839 multiparae at the appropriate age who gave birth to their second child were randomly selected to form the appropriate age multipara group. Univariate analysis was performed by χ² test and analysis of variance, and multivariate analysis was performed by Logistic regression analysis. The differences among the four groups were compared and analyzed, including gestational diabetes mellitus, gestational hypertension, premature delivery, postpartum hemorrhage, and so on.

·Multivariate Logistic regression analysis showed that the elderly primiparas group had the highest risk of gestational diabetes mellitus (aOR=2.938, 95%CI 2.240?3.853), gestational hypertension (aOR=8.579, 95%CI 3.082?23.887), eclampsia (aOR=6.139, 95%CI 2.400?15.985), placenta previa (aOR=3.642; 95%CI 1.551?8.552), turbid amniotic fluid (aOR=4.318, 95%CI 1.852?10.069), premature delivery (aOR=2.573, 95%CI 1.710?3.871), cesarean section (aOR=2.589, 95%CI 1.988?3.373), low birth weight (aOR=3.317, 95%CI 2.111?5.214), neonatal asphyxia (aOR=8.175, 95%CI 2.907?22.992) and respiratory distress syndrome (aOR=10.936, 95%CI 4.400?27.316), compared with the appropriate age multiparae group. The appropriate age primipara group had highest risk of premature rupture of membranes (aOR=1.635, 95%CI 1.337?1.999) and hydramnios/oligohydramnios (aOR=1.730, 95%CI 1.317?2.271), compared with the appropriate age multipara group. The elderly multipara group had the highest risk of developing pelvic adhesions (aOR=1.754, 95%CI 1.030?2.988) compared with the appropriate age multipara group, whereas the appropriate age primipara group had the lowest risk of developing pelvic adhesions (aOR=0.148, 95%CI 0.050?0.439).

·Elderly primiparas confer the highest risks of gestational diabetes mellitus, gestational hypertension, eclampsia, placenta previa, turbid amniotic fluid, premature delivery, cesarean section, low birth weight, neonatal asphyxia and respiratory distress syndrome. Attention should be paid to the perinatal care of elderly primiparas, so that they can receive standardized antenatal visits to improve the quality of their delivery.