Women who were born preterm are at increased risk of complications during pregnancy compared with those born at term, and the risk almost doubles for mothers born before 32 weeks, according to a study.

Pregnancy complications among women in the study included gestational diabetes, gestational hypertension and preeclampsia or eclampsia.

The findings are based on a study of 7,405 women born preterm and 16,714 women born at term between 1976 and 1995 in the Canadian province of Quebec. Of the preterm women, 554 were less than 32 weeks at birth and 6,851 were at 32 to 36 weeks’ gestation.

For the women born at less than 32 weeks, 19.9% had at least one pregnancy complication, compared with 13.2% for those born between 32 and 36 weeks and 11.7% for those born at term.

As reported in other studies, women who were born small for gestational age, whether preterm or term, also were at greater risk of complications during pregnancy. The risk of complications increased with decreasing gestational age even after the researchers controlled for education level.

Chronic hypertension and type 2 diabetes also were more common among women born preterm even though the study cohort was relatively young (ages 32 and younger). When the researchers controlled for these conditions, the risk of pregnancy complications remained significantly higher in women born preterm.

Anne Monique Nuyt, MD, of Sainte Justine Hospital and Research Center at the University of Montreal, and coauthors suggested the higher rates of pregnancy complications in mothers may be linked to underlying conditions related to their preterm births.

"The impact of the patients’ preterm births on obstetric care should be taken into account in the care of pregnant patients, as well as in the allocation of resources in the healthcare system," they concluded.

The study appeared Sept. 24 on the website of the Canadian Medical Association Journal. A PDF of the study is available at www.cmaj.ca/content/early/2012/09/24/cmaj.120143.