Pregnancy complications are more common among women who were themselves born early, a new study finds.
In the report, 19.9 percent of women who were born before 32 weeks of pregnancy had at least one complication, such as gestational diabetes or high blood pressure, when they became pregnant. In contrast, only 13.2 percent of women born between 32 and 36 weeks of pregnancy, and 11.7 percent of women who were born at full-term (at least 37 weeks), experienced a complication during their pregnancy.
"Our study showed that preterm birth was a substantial risk factor for pregnancy complications, especially among women who were born before 32 weeks," the researchers wrote in their study, published today (Sept. 24) in the in the Canadian Medical Association Journal.
Over the past 30 years, the survival of babies born preterm has improved, which may mean that the rates of pregnancy complications will rise in the coming years, the researchers said. Women who experience those complications may in turn face more health problems later on.
"Pregnancy can be considered a stress test for future cardiovascular and metabolic health," the researchers said. For example, studies have shown that women who experience complications during pregnancy are more likely to later develop metabolic syndrome, which is a cluster of medical issues that can include high blood pressure, a large waist and low levels of "good" cholesterol.
Increased survival of preterm babies could also mean that, as those babies age, conditions like cardiovascular disease will increase in the general population.
In the study, the researchers looked at data gathered on women born between 1976 and 1995 in the province of Quebec who delivered at least one baby between 1987 and 2008. The study included 7,405 women who had been born preterm and 16,714 women born at term. The women's average age when they gave birth was 25.
In the U.S., 12 percent of babies are born preterm, according to the World Health Organization.
Results in the recent study showed that the earlier a woman had been born, the greater were her chances of having a complication during pregnancy, even after the researchers took into account factors such as the mother's year of birth, chronic high blood pressure, kidney disease and type 1 or 2 diabetes.
The study also showed that women who were born small for their gestational age, whether they were born preterm or at full-term, were more likely to have pregnancy complications.
While the reason for the link between preterm birth and pregnancy complications isn't exactly clear, it could be that women born preterm have undiagnosed risk factors for complications before they become pregnant, the researchers said. Studies have shown that children and young adults born preterm have higher insulin resistance and blood pressure, which are risk factors for cardiovascular diseases.
While previous studies have shown that babies born with low birth weight are at an increased risk of high blood pressure as adults, the new findings show that preterm birth, independent of birth weight, may be linked to such conditions in adulthood.
"The impact of the patients’ preterm birth on obstetric care should be taken into account in the care of pregnant patients," the researchers said.
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