Finding the cause for serious pregnancy disorder marks first step towards treatment
Healthy development – Preeclampsia
The high blood pressure drugs that are currently prescribed to women suffering from preeclampsia act like a hammer aimed at a pinhead.
“The drugs knock out other things as well, with inevitable side effects,” says Dr. Margie Davenport, who is co-leading a study of preeclampsia, a serious condition that affects about eight per cent of pregnant women in developed countries and puts both mothers and babies at risk.
Preeclampsia has increased by 25 per cent in the past two decades, partly as a result of increasing maternal age (in Canada, a third of first-time mothers are 35 or older) and obesity. It occurs after the 20th week of pregnancy, causing high blood pressure, stiffer arteries and decreased heart and kidney function. Women who develop the disorder are at high risk for future cardiovascular disease.
Despite the seriousness and growing incidence of preeclampsia, its causes are still unknown and there is no cure other than trying to control mom’s high blood pressure and inducing delivery of the baby.
Research has shown that the sympathetic nervous system (which controls the body’s fight or flight stress response) is hyperactive in women with preeclampsia. This is important because other research has demonstrated a close connection between sympathetic nervous system hyperactivity and high blood pressure and cardiovascular problems in other diseases.
Dr. Davenport and Dr. Craig Steinback, co-leaders of the study, aim to determine the reason for sympathetic hyperactivity in preeclampsia. They are specifically looking at the peripheral chemoreflex, which normally controls minute-by-minute breathing. This mechanism is also crucial for controlling the activity of the sympathetic nervous system and has been successfully targeted in treating hypertension in other diseases. They suspect that this mechanism may be hyperactive in women with preeclampsia as well, causing blood vessels to contract and raising blood pressure.
“The initial data appears to support this hypothesis,” says Dr. Steinback. If the findings are confirmed, this would be a prerequisite step in work on a specific therapy that targets the chemoreceptors in order to stabilize blood pressure. Identifying the cause will enable the researchers to develop a more directed, effective drug or other treatment, with fewer side effects than the broad-based approach now used that hammers the whole sympathetic nervous system.
Drs. Davenport and Steinback are pleased to be working together on what they see as “an essential first step” to developing an earlier diagnosis, better treatment and possible preventions for preeclampsia. The two researchers not only share professional interests, but parenting responsibilities for two young daughters, aged 2 ½ and six months. It’s been something of a relay race for the husband-and-wife team: Dr. Davenport has just completed her maternity leave and is returning to the study, while her husband goes on paternity leave and picks up the child care.
The two-year study was supported by generous supporters of the Lois Hole Hospital for Women through a WCHRI Innovation Grant.