Maternal age and preterm births in singleton and twin pregnancies conceived by XXXX in the United States.

@entity52 @entity1 @entity600
BACKGROUND: Among natural conceptions, advanced maternal age (>= 35 years) is associated with an increased risk of @entity600 . However, few studies have specifically examined this association in births resulting from @entity52 ( @entity52 ). METHODS: A retrospective cohort study was conducted in 97   288 singleton and 40   961 twin pregnancies resulting from fresh non-donor @entity52 cycles using 2006-10 data from the Society for Assisted Reproductive Technology Clinic Online Reporting System. RESULTS: Rates of very early preterm (<28), early preterm (<32), and @entity600 (<37 completed weeks) decreased with increasing maternal age in both singleton and twin births (PTrend <0.01). With @entity1 aged 30-34 years as the reference, those aged <30 years were at an increased risk of all types of preterm births. The adjusted odd ratio (95% confidence interval [CI]) for very early @entity600 , early @entity600 , and @entity600 in @entity1 aged 25-29 years were 1.3 [95% CI 1.1, 1.5], 1.2 [95% CI 1.1, 1.4], and 1.1 [95% CI 1.02, 1.2] in singletons. This increased risk of preterm births among younger @entity1 was even more significant in twin births. However, @entity1 aged >= 35 years were not at an increased risk of any type of preterm births in both singleton and twin births. CONCLUSIONS: In contrast to natural conception, advanced maternal age is not associated with an increased risk of preterm births in pregnancies conceived by @entity52 . @entity1 who seek @entity52 treatments before 30 years old are at higher risk of all stages of preterm births.
