When a woman carries more than one baby, her risk of premature delivery skyrockets. Each additional baby increases the risk significantly: The preterm rates are approximately 60 percent for twins, 90 percent for triplets, and about 100 percent for quadruplets and beyond.
Why the dramatic risk increase? Additional babies stretch the uterus and compete for limited nutrients. Multiple pregnancies also put extra strain on the mother's body, sometimes leading to complications like anemia, high blood pressure, and early labor, according to the American Congress of Obstetricians and Gynocologists (ACOG).
And if you think you've seen a rise in multiple births in the United States, you'd be right. Women are getting pregnant later in life and moms in their 30s and 40s are most likely to conceive more than one baby. Adding to the odds of giving birth to multiples? Fertility treatments.
Did You Know?
To help stem the tide of multiple births, the American Society of Reproductive Medicine recently issued guidelines limiting the number of embryos that can implanted during in vitro fertilization.