A new study from the Institute for Clinical Evaluative Sciences (ICES) and St. Michael’s Hospital shows that features of metabolic syndrome, including obesity, diabetes, and high blood pressure and cholesterol, pose a risk to pregnancy.
The study, led by Dr. Joel Ray, found that pregnant women with metabolic syndrome were more likely to experience placenta-related complications, including pre-eclampsia (new-onset hypertension in pregnancy after 20 weeks gestational age, in association with protein in the urine), gestational hypertension (new-onset hypertension in pregnancy after 20 weeks gestational age, without associated protein in the urine), placental infarction (blockage of blood circulation to a localized area of the placenta), or placental abruption (the premature separation of the placenta from the uterine wall).
Researchers looked at more than one million women in Ontario who had a first delivery between 1990 and 2002, and found that seven per cent of them experienced one or more of these complications. The more features of metabolic syndrome a woman had, the greater her risk of a placenta-related complication. Women with one feature – for example, diabetes – were three times more likely to have a placenta-related problem; women with three or four features were almost eight times more likely to experience a problematic pregnancy.
The study’s researchers believe that the reason for the link between metabolic syndrome and these pregnancy complications may be caused by diseased placental blood vessels. “The placenta is made up of a complex network of tiny blood vessels, and the metabolic syndrome likely creates a problem within these vessels,” says Dr. Ray. “Moreover, if you have problems with the blood vessels of the placenta, which provide oxygen and nutrients, the fetus will not grow properly while in the womb.”
Dr. Ray and his colleagues suggest that placental complications might be detected earlier in women who exhibit more than one feature of the metabolic syndrome. Greater surveillance of women with several features of metabolic syndrome is recommended, including regular testing for high blood pressure and pre-eclampsia at all prenatal visits, and one or two ultrasounds in the third trimester of pregnancy.
The study, published in the December 2005 issue of the Journal of Obstetrics and Gynaecology Canada, closely follows publication of a sister study that demonstrated that women with pregnancy complications related to the placenta are at a higher risk of developing premature heart disease. Both studies are part of a larger effort to identify women with diseased blood vessels and thereby prevent future complications.
Author affiliations: ICES (Drs. Vermeulen, Schull, and Redelmeier); Departments of Medicine, Health Policy, Management and Evaluation, and Obstetrics and Gynecology, and the Division of Endocrinology and Metabolism, St. Michael’s Hospital, University of Toronto (Dr. Ray); Departments of Medicine, and Health Policy, Management and Evaluation, Sunnybrook and Women’s College Health Sciences Centre (Drs. Schull and Redelmeier); Department of Obstetrics and Gynecology, McMaster University (Dr. McDonald).
ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.
St. Michael's Hospital is a large and vibrant Catholic teaching and research hospital in the heart of Toronto. Fully affiliated with the University of Toronto, St. Michael's Hospital leads with innovation, and serves with compassion. Renowned for providing exceptional patient care, St. Michael's Hospital is a regional trauma centre and downtown Toronto's designated trauma centre for adults. For more information, please visit www.stmichaelshospital.com.
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