Multiple Births Multiply During Past Two Decades

Contact: NCHS Press Office, Sandra Smith or Jeff Lancashire, 301-436-7551

MULTIPLE BIRTHS MULTIPLY DURING PAST TWO DECADES

There has been a remarkable rise in the number of triplet and other higher-order multiple births over the past two decades. Up from 1,034 births in 1971 to 4,594 for 1994, the increase in higher-order multiple births (triplets, quadruplets and quintuplets) reflects the rising number of births to women in their thirties, who are more likely to have a multiple birth, and the use of fertility-enhancing drugs and techniques. Yet, babies born in triplet and other higher-order multiple deliveries arrive smaller and earlier than single births and are at greater risk of infant death and life-long health problems.

A new report from the National Center for Health Statistics examines the trends in triplet and other higher-order multiple births (from now on referred to as triplets or triplet births) and their birth outcomes and infant mortality compared with single births.

The number of live births in triplet deliveries tripled between 1980 and 1994 and quadrupled since 1971. Over the last decade, increases in the number of triplet births averaged 11 percent a year. The ratio of triplet births per 100,000 births rose over 200 percent between 1980 and 1994. In 1994, the 4,594 triplet and other higher-order multiple births included 4,233 triplets, 315 quadruplets, and 46 quintuplets and greater births.

The overall rise in the triplet birth ratio can be attributed almost exclusively to the rise in these births among white mothers, for whom the ratio rose by 252 percent between 1980 and 1994. Among black mothers, the ratio rose by only 52 percent and most of this increase is fairly recent, occurring since the mid to late 1980s.

The major factor underlying the increase in triplet births appears to be the use of ovulation-enhancing drugs and assisted reproductive techniques, such as in vitro fertilization. Only one-third of this increase reflects the shift in maternal age, with more babies born to mothers in their thirties. Overall, increases in triplet births were most pronounced among married, college-educated mothers 30 years of age and older.

The report examines ratios by state. Massachusetts reported the highest triplet birth ratio for combined years 1992-94, more than twice as high as the nation as a whole. Other states reporting ratios at least 50 percent higher than the U.S. as a whole were New Hampshire, New Jersey and Iowa. These states also tended to have higher proportion of births to older, non-Hispanic white mothers.

Triplet births are at much greater risk than single births. Infant mortality rates are 12 times higher for these births than for single births. The average birth weight of a triplet newborn is only half that of a single birth and the period of gestation is, on average, 7 weeks shorter. The report, "Triplet Births: Trends and Outcomes, 1971-94, by Joyce A. Martin, Marian F. MacDorman, and T.J.Mathews, concludes that the precarious health status of triplets and other higher-order multiple births and their rising numbers make further research into these births of growing importance.

Data in this report are based 100 percent of the birth certificates registered in all States and the District of Columbia and reported to the NCHS through the National Vital Statistics System. For more information or for a copy of this report, contact the NCHS Public Affairs Office at (301) 436-7551 or by email at: [email protected]. A copy of the full report can be viewed or downloaded from the NCHS Home Page at http://www.cdc.gov /nchswww/ nchshome.htm.