Women with multiple pregnancies are at a higher risk of pregnancy-related death than those with single pregnancies. Researchers from the National Center for Health Statistics at the Center for Disease Control and Prevention in Maryland, USA, found that this higher risk was seen across the board, regardless of age, race, marital status and level of education. In the past 20 years, twin birth rates have increased by 55 percent in the United States and other higher order birth rates increased 388 percent. It's believed to result primarily from the increased use of fertility treatments. A second factor is that women are having pregnancies at an older age, which is believed to increase the risk of multiple or multi-fetal 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 the researching team identified 4,992 pregnancy-related deaths between 1979-2000, nearly 4 percent of which were among women with multiple pregnancies. The risk of pregnancy-related death was much higher for multiple pregnancies (21 per 100,000 live multi-fetal births) than for singleton births (6 per 100,000 live singleton births). The risk of pregnancy-related death among women with twins and higher-order pregnancies was nearly 4 times that seen in women with singleton pregnancies. This higher risk was suspected because it's already been shown in the past that risks of morbidity increase with multiple pregnancies. The leading causes of death were similar for women who gave birth to a single child and for those with multiple pregnancies. Embolism (blood clot), haemorrhage, and hypertensive disorders of pregnancy were the three leading causes.
Obstetrics and Gynecology,
March 2006