How common are multiple births?
A study published in the January 2003 issue of Obstetrics & Gynecology showed a 59 percent increase in rates of multiple births in the past 20 years, with the highest increase in rates among white women, higher-order births (triplets or more), older women and women in the Northeast. The study also found the twin birth ratio increased more than 59 percent for Caucasian births compared with 34 percent among African-American births; women aged 40 to 44 years experienced the greatest increase in multiple births (110 percent), followed by women aged 35 to 39 years (81 percent) and those aged 30 to 34 years (62 percent). There also was a 423 percent increase in higher-order births (triplets or more) among women of all ages, with the largest higher-order birth ratio in the Northeast (235.2 per 100,000 live births), followed by the Midwest with 212.7, after adjusting for maternal race and age. This dramatic increase in multiple and higher-order births may be highly attributable to the increase
