Koji Nishijima

Aim In this review, We compared clinical characteristics of pregnant women aged 50 and older with those aged 45–49. Pregnant women ≥45 years are strongly associated with pregnancy‐related complications, such as cesarean section rate, gestational hypertension, gestational diabetes mellitus, and preterm birth. Although pregnant women ≥50 years are considered more high‐risk, differences in pregnancy outcomes between those over 45 and 50 years of age are unclear. Methods Our source strategy included using PubMed, the Cochrane Central Register of Controlled Trials, and Web of Science databases to include studies published between January 1, 2010 and September 30, 2022. The study population was pregnant women 50 years and older; the control group was pregnant women aged 45–49 years. Primary outcomes were cesarean section, gestational hypertension, gestational diabetes mellitus, and preterm birth. The secondary outcomes were small‐for‐gestational age, 5‐min Apgar score < 7, neonatal intensive care unit admission (as neonatal outcomes), nulliparity, assisted reproductive technology (ART), and multifetal pregnancy (as maternal backgrounds). Results The incidence of cesarean section, gestational hypertension, and preterm delivery was significantly higher in those 50 years and older; however, significant differences disappeared when pooled analyses were limited to singleton pregnancies. ART was significantly more likely to be used for conception of pregnant women ≥50 years. Infants of women ≥50 years were more likely to be admitted to NICUs. Conclusions The differences in outcomes between the two groups are obviously influenced by multiple pregnancies, therefore, reproductive medicine specialists should aim for singleton pregnancies in ART.