Women who were born preterm are at increased risk of complications during pregnancy compared to those born at term, and the risk almost doubles for mothers born before 32 weeks, according to a study in CMAJ (Canadian Medical Association Journal).
Pregnancy complications include gestational diabetes, gestational hypertension, and preeclampsia or eclampsia.
The findings are based on a study of 7405 women born preterm and 16 714 women born at term between 1976 and 1995 in the province of Quebec. Of the preterm women, 554 were less than 32 weeks at birth and 6851 were at 32 weeks' gestation.
"We found that the risk of pregnancy complication was significantly higher among women born preterm, independently of their own fetal growth," writes Dr. Anne Monique Nuyt, Sainte-Justine University Hospital and Research Center, University of Montréal, with coauthors. "When divided into categories of gestational age, the risk of having at least 1 pregnancy complication nearly doubled among women born before 32 weeks' gestation versus those born at term."
For the women born at less than 32 weeks, 19.9% had at least 1 pregnancy complication compared with 13.2% for those born between 32 and 36 weeks and 11.7% for those born at term.
Women who were born small for gestational age, whether preterm or term, were also at greater risk of complications during pregnancy, a finding reported in other studies. When the researchers controlled for education level, they still found that the risk of complications increased with decreasing gestational age. Chronic hypertension and type 2 diabetes were also more frequent among the women born preterm, even though the cohort studied was still relatively young (maximum age 32 years), which is also a new finding reported by this study. However, when the researchers controlled for these conditions (which are known to increase the risk of pregnancy complications), the risk of pregnancy complications remained significantly higher in women born preterm.
Over the past 30 years, significantly more babies born before 32 weeks' gestation have survived, which may mean that a larger population will be at risk of hypertension, type 2 diabetes and health issues related to these diseases.
The authors suggest that 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 birth on obstetric care should be taken into account in the care of pregnant patients, as well as in the allocation of resources in the health care system," conclude the authors.