Pregnant mothers over 40 may have elevated risk of preterm birth

Pregnant mothers over 40 may have elevated risk of preterm birth

More mothers are becoming pregnant later in life, and while some pregnancy complications occur with greater frequency among older mothers, whether preterm birth can be independently associated with maternal age has required more investigation.

In a new PLOS ONE study, Florent Fuchs and colleagues found that women of advanced maternal age (40 years and over) had the highest rates of preterm birth (less than 37 weeks) and extremely preterm birth (less than 32 weeks), even when adjusting for known risk factors for preterm birth that may have complicated the analysis. Mothers between 30 and 34 years of age had the lowest risk of preterm birth.

Fuchs’ research team used data that had previously been collected for the QUARISMA clinical trial, which tested a strategy to reduce cesarean sections in 32 hospitals in Quebec, Canada over a three-year period. For the new study, the researchers included QUARISMA data on 165,282 pregnancies and distributed them into five age groups based on maternal age.

Even after accounting for other factors that could influence risk of preterm birth — such as placenta previa, gestational diabetes, never having given birth before, smoking and other risk factors — the analysis showed that advanced maternal age may be independently associated with higher risk of preterm delivery. These results are consistent with similar studies probing this question, Fuchs and colleagues claim.

The researchers note that while their statistical analysis accounted for numerous other factors that could potentially influence preterm birth, data on body mass index  was missing for 28 percent of the patients and was excluded as a result.

Reference: Fuchs F, Monet B, Ducruet T, Chaillet N, Audibert F (2018) Effect of maternal age on the risk of preterm birth: A large cohort study. PLoS ONE 13(1): e0191002.

Image Credit: Antonio Thomás Koenigkam Oliveira, Flickr


Sara Kassabian is the Social Media Programs Manager at PLOS, where she spends a lot of time writing and editing content for different digital platforms, as well as managing social media strategy and editorial operations for the PLOS Blogs Network ( Sara is a former journalist who completed her MS in Global Health at the University of California San Francisco (UCSF), where her research focused on the prioritization of maternal and newborn health in global health policy. She can be reached by email at and on Twitter @sarakassabian.

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