Pregnancy complications up to twice higher in women born preterm

Women who were born premature are more likely to have pregnancy complications than women who weren’t, according to data analyzed by a team lead by Dr. Anne Monique Nuyt, a neonatal specialist and researcher at the Sainte-Justine Mother and Child University Hospital Center and University of Montreal. This is the first study to clearly show the impact of preterm birth (i.e. before 37 weeks of gestation) itself on pregnancy risks. “We knew that to be born with a low birth weight could be associated with increased risk of pregnancy complications, but with this study we isolated the “born preterm factor” and show that being born premature has a major impact on pregnancy complications,” Nuyt said. The results of Nuyt’s studies were published online by the Canadian Medical Association Journal on September 24, 2012.

They examined the data from all women born preterm between 1976 and 1995 and who had delivered at least one infant between 1987 and 2008. “We took all women born preterm and selected twice as many “at-term” women as representative controls for this study,” Nuyt explained. There were 7,405 women in the born preterm group during the study period. “The findings show that just over one in ten pregnancies involves complications in mothers who were carried to full term. However, this figure rises to one in five for women who were born before 32 weeks of gestation.” The researchers were able to undertake their study with high quality data and precise information as all births, with weight and gestational age, and all hospital diagnosis and interventions that take place in Quebec are recorded in universal databases that can be used to generate health statistics. The researchers were able refine their query to include women who were born between 24 and 42 weeks gestation and were also able to correct their statistics to take into account other health conditions and social factors that may influence pregnancy-related complications.

Scientists have known for some time that women whose weight was low at birth have a higher risk of health issues during pregnancy, including gestational hypertension, gestational diabetes and preeclampsia. However, it was unclear whether being born preterm alone had an impact.

This research establishes that, independently of weight at birth (i.e. whether too small or normal for gestational age), baby girls born preterm show a significant increase in their risk of developing pregnancy complications, and that the risk increases the more premature the woman was born.

As the rate of survival of preterm babies has increased significantly over the past 30 years, it is important for researchers to improve the understanding of the health risks for this increasingly large percentage of the population. “Seven per cent of young adults in Quebec were born prematurely,” Nuyt said. “The impact of preterm births on obstetric care should be taken into account by professionals providing care directly to patients and by managers allocating resources within the health care system.”


This work was funded by a Canadian Institutes of Health Research (CIHR) operating grant (no. MCH-97584). The researchers received funding from the Fonds de recherche du Québec – Santé, the CIHR, and the Fonds de recherche du Québec – Société et culture. Sainte-Justine Mother and Child University Hospital and the University of Montreal are known officially as Centre hospitalier universitaire Sainte-Justine and Université de Montréal, respectively.


William Raillant-Clark
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University of Montreal

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