Carrying multiple babies risky for mom: study

By Clementine Wallace

NEW YORK (Reuters Health) - Women with multifetal pregnancies have a higher risk of pregnancy-related death than those with singleton pregnancies, according to a report in the journal Obstetrics and 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 percent in the United States and other higher order birth rates increased 388 percent, 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 percent of triplets and other higher-order births resulted from spontaneous conception, the rest resulted from either assisted reproductive technology (ART) or ovulation-inducing drugs.

Using U.S. national data from the CDC's Pregnancy Mortality Surveillance System, MacKay's team identified 4,992 pregnancy-related deaths between 1979-2000 -- 4.2 percent of which were among women with multifetal pregnancies.

The risk of pregnancy-related death was much higher for multifetal pregnancies (20.8 per 100,000 live multifetal births) than for singleton births (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 (blood clot), hemorrhage, and hypertensive disorders of pregnancy were the three leading causes, according to MacKay.

SOURCE: Obstetrics and Gynecology March 2006.