Last Updated on Tuesday, July 03, 2012 Tuesday, July 03, 2012
By Caryn Rogers, Foundation Science Writer - For decades, doctors informed women that preeclampsia was temporary. Even though women might get very sick, if delivery set the healing process in motion quickly enough, their bodies would heal. They were expected to recover completely. Although their babies may have been affected by the resulting prematurity, the preeclampsia itself was not confirmed to cause any direct health concern to the children either. That is to say, preeclampsia was considered “transient.”
However, recent research suggests that not only are preeclamptic mothers more likely to develop cardiovascular disease (CVD) but the offspring of these pregnancies may have higher body mass index (BMI) and blood pressure readings and be at higher risk for later effects such as stroke or heart disease than children born to normotensive - that is, normal blood pressure - pregnancies.
Physician-researchers who work on preeclampsia have described it as a “stress test for life.” Under the added physical strain of pregnancy, women get a glimpse of what their future health challenges may be.
Is preeclampsia an indicator that we're predisposed to develop heart disease? Or does it cause damage that results in this long term impact? In any case, what do we do with this information, for ourselves and for our children?
Genetics may provide part of the explanation. Women who develop preeclampsia often have genes that make them more likely to develop chronic hypertension than the average population. Since chronic hypertensives pass their genes on to their children, their children would likewise have a higher risk for hypertension and related problems.
According to an explanation known as the Barker Hypothesis, those genetic susceptibilities might be related to development of the baby during pregnancy. Children who develop in a uterine environment where nutrition is scarce, whether that's the result of famine or IUGR, are developmentally programmed to "expect" that calorie shortage to continue and store additional fat accordingly. In our modern environment where calories are abundant, those children might easily grow into overweight adults. Though this doesn't always result in obesity - many people are adept at controlling their weight - but the underlying tendency of the body to expect food scarcity is still present. It’s called the "thrifty phenotype."
"Many women with a thrifty phenotype end up with partners who also have a thrifty phenotype," explains Dr. Thomas Easterling, Professor of Medicine and Director of the Maternal Hypertension Clinic at the University of Washington (Seattle) and Director of the Preeclampsia Foundation's Medical Advisory Board. "That means the children are carrying genes from both parents that put them at higher risk of these conditions, making cardiovascular disease more likely."
Children from preeclamptic pregnancies may appear physically the same as children from normotensive pregnancies. Statistically, however, there appears to be a small but significant difference in their blood pressure and BMI measurements. For example, an average ten-year-old male child born to a normotensive pregnancy and in the 50th percentile for height and weight should have a blood pressure of 102/61. The same child born to a preeclamptic pregnancy would score just slightly higher, at around 104/63.
That seems like such a slight variation that could easily be explained by a number of factors, like a rushed reading or a bulky shirt. But when it shows up in a population of over 45,000 children, as was seen in recent research, the odds that difference appears by chance drop to less than one in ten thousand. Over the long run, that difference can grow to be a major risk marker for CVD.
What about the other alternative - the possibility that preeclampsia itself is causing some damage?
Endothelial damage caused by preeclampsia may not be entirely reversed post-preeclampsia. It may cause permanent hyperreactivity in the immune system, which could be why some women exhibit new or exacerbated autoimmune disorders or chronic hypertension following a pregnancy complicated by preeclampsia.
"We really need a population-based study to answer this question," says Dr. Vesna Garovic, Professor of Medicine at the Mayo Clinic in Rochester, Minn. "The studies, to date, have not addressed the role of preeclampsia as a possible cause of cardiovascular disease. However, absence of evidence isn't evidence of absence - future studies focusing on this particular issue are needed."
Dr. Easterling agreed. "There are some studies that might be interpreted as showing damage from preeclampsia. However, we know we can explain most of this with regular genetics. In the long run, we might find that the Barker Hypothesis -- the idea that the way these babies develop in utero is altered by the environment they experience -- helps to explain these findings."
So what can we do about this risk marker for heart disease that appears in us and perhaps in our children?
"Lifestyle impacts are substantial," says Audrey Gardner, director of echocardiography at CHOC - Children's Clinical Specialists cardiology division in Orange, Calif. She experienced Class I HELLP in her pregnancy with her daughter Rebecca. "There are so many factors that can affect our children - complicated pregnancies, NICU time, surgeries, anesthesia, genes - where we have no control. But we can continue to make careful diet and exercise choices, we can quit smoking, and we can monitor our own health and follow up with appointments as necessary. And yes, it's hard to find the time to do that with young children. But it could mean we catch our arterial changes before we have bad outcomes."
"We don't have data suggesting women with a history of preeclampsia, or their children, need aggressive monitoring or treatment, but they do need to be followed as at risk, and supported in healthy lifestyles," added Dr. Garovic. "One positive is that this disease serves as an early marker of risk, so that we can catch people at a younger age."
The American Heart Association’s 2011 Guidelines for the Prevention of Cardiovascular Disease (CVD) in Women continue to prioritize lifestyle approaches for the prevention of CVD. Known as "Life"s Simple 7," the AHA has defined what it means to have ideal cardiovascular health, identifying the most important health and behavior factors that impact health and quality of life. These 7 simple, small changes can make a big difference in living a better life - for you and your children - and getting ahead of the risks presented by your preeclampsia history.