Effect of maternal age on the risk of preterm birth: A large cohort study

Abstract

BackgroundMaternal age at pregnancy is increasing worldwide as well as preterm birth. However, the association between prematurity and advanced maternal age remains controversial.ObjectiveTo evaluate the impact of maternal age on the occurrence of preterm birth after controlling for multiple known confounders in a large birth cohort.Study designRetrospective cohort study using data from the QUARISMA study, a large Canadian randomized controlled trial, which collected data from 184,000 births in 32 hospitals. Inclusion criteria were maternal age over 20 years. Exclusion criteria were multiple pregnancy, fetal malformation and intra-uterine fetal death. Five maternal age categories were defined and compared for maternal characteristics, gestational and obstetric complications, and risk factors for prematurity. Risk factors for preterm birth <37 weeks, either spontaneous or iatrogenic, were evaluated for different age groups using multivariate logistic regression.Results165,282 births were included in the study. Chronic hypertension, assisted reproduction techniques, pre-gestational diabetes, invasive procedure in pregnancy, gestational diabetes and placenta praevia were linearly associated with increasing maternal age whereas hypertensive disorders of pregnancy followed a “U” shaped distribution according to maternal age. Crude rates of preterm birth before 37 weeks followed a “U” shaped curve with a nadir at 5.7% for the group of 30–34 years. In multivariate analysis, the adjusted odds ratio (aOR) of prematurity stratified by age group followed a “U” shaped distribution with an aOR of 1.08 (95%CI; 1.01–1.15) for 20–24 years, and 1.20 (95% CI; 1.06–1.36) for 40 years and older. Confounders found to have the greatest impact were placenta praevia, hypertensive complications, and maternal medical history.ConclusionEven after adjustment for confounders, advanced maternal age (40 years and over) was associated with preterm birth. A maternal age of 30–34 years was associated with the lowest risk of prematurity.

Risks of preterm birth among non‐Hispanic black and non‐Hispanic white women: Effect modification by maternal age

“…However, this interpretation does not imply that maternal age and race/ethnicity are not associated with PTB. Numerous studies have demonstrated that women at the extremes of age (compared with those in their 20s) and black women (compared with white women) experience increased risk of PTB, which our results confirm. Rather, the findings presented here suggest that the effect of maternal age on PTB and its subtypes among primiparous women does not vary by race.…”

Prevalence and predictors of gestational diabetes mellitus: a nationwide multicentre prospective study

“…The prevalence of GDM increased markedly with increasing maternal age, from ~ 6.9% among women aged < 25 years to 32.7% among women aged ≥ 36 years. Similarly, in a large Canadian retrospective cohort study using data from the QUARISMA trial, the rate of GDM more than doubled (19.4% vs. 8.7%) in women aged > 40 years compared with those aged 30–34 years .…”

“…In line with previous studies [2,15,18], our results showed a strong association of GDM with maternal age. The prevalence of GDM increased [22]. Several studies have reported that pre-pregnancy BMI and obesity are independently associated with a higher prevalence of GDM [15,18,23].…”

Perinatal and familial risk factors for soft tissue sarcomas in childhood through young adulthood: A population‐based assessment in 4 million live births

“…For example, it has been suggested that younger mothers in more recent years may be more likely to experiment with recreational drugs, which is a suspected risk factor for RMS . Additionally, younger maternal age (<25 years) has been associated with some adverse pregnancy and birth outcomes (e.g., gestational hypertension and preterm birth), which could influence STS risk . However, these differences could be due to unmeasured confounding (e.g., socioeconomic status).…”