By Clementine Wallace

NEW YORK (Reuters Health) Mar 29 - Women with multifetal pregnancies have a higher risk of pregnancy-related death than those with singleton pregnancies, according to new findings published in the March issue of Obstetrics & Gynecology.

"This higher risk was seen across the board, regardless of age, race, marital status and level of education," lead author Andrea P. MacKay, from the National Center for Health Statistics at the Center for Disease Control and Prevention in Hyattville, Maryland, told Reuters Health.

In the past 20 years, twin birth rates have increased 55% in the United States and higher order birth rates increased 388%, according to the authors.

"It's believed to result primarily from the increased use of fertility treatments," said MacKay. " A second factor is that women are having pregnancies at older ages, which is believed to increase the risk of multifetal pregnancies."

In 2000, for example, only 18% of triplets and other higher-order births resulted from spontaneous conception, the rest resulted from either ART or ovulation-inducting drugs.

To assess the relationship between pregnancy-related deaths and multiple pregnancies, and identify the risk factors associated with these deaths, the team conducted the first analysis using national data -- the CDC's Pregnancy Mortality Surveillance System.

The team identified 4992 pregnancy-related deaths between 1979-2000, 4.2% of which were among women with multifetal pregnancies.

The risk of pregnancy-related death was 20.8 per 100,000 live multifetal births compared with 5.8 per 100,000 live singleton births. The risk of pregnancy-related death among women with twins and higher-order pregnancies was 3.6 times that seen in women with singleton pregnancies.

"We suspected this higher risk because it's already been shown in the past that risks of morbidity increase with multifetal pregnancies," said MacKay.

The leading causes of death were similar for women who gave birth to a single child and for those with multifetal pregnancies. Embolism, hemorrhage, and hypertensive disorders of pregnancy were the three leading causes, according to MacKay.

Reuters Health Information 2006. © 2006 Reuters Ltd.
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