Cholesterol, inflammation tied to preterm birth
By Amy Norton
NEW YORK (Reuters Health) - High cholesterol and inflammation during pregnancy may increase a woman's odds of premature delivery, a study suggests.
Researchers found that pregnant women with elevated levels of cholesterol or C-reactive protein -- a marker of inflammation in the body -- were at increased risk of having their baby prematurely. Elevations in both measures raised the risk even further.
The findings suggest that metabolic abnormalities, together with inflammation, may contribute to preterm birth, the researchers report in the American Journal of Epidemiology.
Researchers have suspected that low-grade inflammation in the body may contribute to premature births. Studies have shown that women who give birth preterm are more likely than other women to develop heart disease later in life. Women who deliver prematurely have been shown to have relatively high blood levels of C-reactive protein (CRP), and elevated CRP levels are known to be linked to an increased risk of heart attack.
Inflammation normally occurs during pregnancy, explained Dr. Janet M. Catov of the University of Pittsburgh in Pennsylvania, the lead researcher on the new study.
But women who deliver prematurely may have excess inflammation, she told Reuters Health. When this occurs along with elevated cholesterol or triglycerides (another type of blood fat), the two may act together to increase the odds of preterm birth.
For their study, Catov and her colleagues compared 109 women who gave birth prematurely with 228 who went full-term (about 40 weeks). During pregnancy, all of the women had their cholesterol and triglyceride levels tested; elevations in either are collectively known as dyslipidemia. CRP levels were also measured.
The researchers found that women with dyslipidemia early in pregnancy -- before the 21st week -- were twice as likely as women with normal cholesterol and triglycerides to deliver between the 34th and 37th week of pregnancy.
This risk was three-fold higher in women with elevated CRP levels early in pregnancy, versus women with normal levels. When women had both dyslipidemia and high CRP, the risk of delivering very early -- before the 34th week -- increased six-fold, the researchers found.
The reasons for the findings are uncertain. One possibility, according to Catov's team, is that inflammation and high cholesterol or triglycerides disrupt the normal development of the placenta.
Catov said it's too soon to talk about possible treatment implications -- whether, for instance, lowering a woman's cholesterol might cut the risk of preterm delivery.
"Our results need to be confirmed by others, and ideally we need to know if inflammation and dyslipidemia might be present before pregnancy," she explained.
It will also be important to see whether the two conditions persist after pregnancy, according to Catov. If they do, that might affect a woman's subsequent pregnancies, or possibly her risk of heart disease later in life.
SOURCE: American Journal of Epidemiology, December 1, 2007.