The researchers also found that mothers who continue to smoke cigarettes during pregnancy are not only harming health of the developing fetus but are doubling their own risks of dying from future heart disease or from any cause.
These insights have important public health implications, the researchers continued, because they identify young pregnant women as a previously underappreciated group of patients who would appear to benefit from targeted prevention efforts, including smoking cessation efforts.
"Given the high percentage of women who continue to smoke during their pregnancy, targeting this behavior would not only benefit the health of the fetus but reduce the mother's future risk for early death," said Duke cardiologist Mimi Biswas, M.D. Biswas presented the results of two separate analyses March 13, 2006, during the 55th annual scientific sessions of the American College of Cardiology in Atlanta.
Biswas's research is supported by the National Institutes of Health's Building Interdisciplinary Research Careers in Women's Health (BIRCWH) Fellowship and the ACC Foundation/Guidant Foundation Fellowship and Career Development Award in Women's Cardiovascular Health.
"The complications during pregnancy that we studied could have lasting effects on the cardiovascular system and can be seen as novel early warning signs of future heart disease or mortality risk," she continued. "Typically, younger women tend not to be closely followed for cardiovascular disease – based the results of our analyses, those with difficult pregnancies should be.
"Knowing that these complications may have ramifications later in life gives us a unique opportunity to catch women early," Biswas said. "When women are young, they may tend to focus on the care of their babies and gloss over going to the doctor for their own care.
While population studies have associated complications during pregnancy with adverse outcomes for the mother later in life, few studies have sought to quantify the degree of risk, the researchers said.
In their studies, the researchers used the Perinatal Health Services Outcomes Database -- which includes all women who gave birth at Duke between 1979 and 2005 -- and the Duke Information System for Cardiovascular Care, which included all patients who received a cardiac catheterization since 1969. They searched the databases for patients who appeared on both, and separated them into two groups – one that had complications during pregnancy and one that did not.
For their analyses, pregnancy complications included preeclampsia, gestational diabetes or preterm birth, in utero fetal death, small- and large-for gestational age, post-partum hemorrhage, stillbirth and twins.
In their study, the Duke team performed two analyses – one that looked for association between pregnancy complications and the development of cardiovascular disease seen on cardiac catheterization, while the other looked for association with mortality, both cardiac and from all causes.
In the coronary artery disease analysis, 210 out of 404 patients who appeared on both databases had pregnancy complications; while 183 out of 339 patients in the mortality analysis had complications. In general, the women with pregnancy complications had higher rates of diabetes, hypertension, smoking during pregnancy and confirmed coronary artery disease on catheterization.
"However, after statistically adjusting for those medical risks factors, we still found that pregnancy complications added an independent 1.6-fold risk for the development of cardiovascular disease," Biswas said. "Again, after adjusting for those medical factors, we also found that pregnancy complication was an independent risk factor for all-cause death, increasing that risk over two-fold."
The researchers also found that after adjusting for the other clinical variables, smoking more than doubled the risk of all-cause death, almost tripled the risk of cardiac death, and almost doubled the risk of developing coronary artery disease.
For the coronary artery disease analysis, the average age of delivery was 28 years and 42 was the average age at catheterization. In the mortality analysis, average age of delivery was 27 and 41 years for catheterization.
"We know that in general, when women come to the hospital with a heart attack, they tend to be older and have diabetes and hypertension, and they tend to have worse outcomes," she continued. "But if we could identify them early in life, we could take the appropriate preventative measures and forestall the bad outcomes. Pregnancy history can be a red flag to identify women at increased future risk."
Since the women with the worse outcomes tend to be younger, the Duke team plans further studies looking for genetic factors that may be involved. As older women come to the catheterization labs for treatment, the team is also collecting past obstetric information as well.
Other members of the Duke team included Monique Chireau, M.D., Emily Honeycutt MBI, Haywood Brown, M.D., Kristin Newby, M.D., and Lori Bastian, M.D.
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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