Multiple birth rates for 2007 were released in August 2010. Here are some highlights:
Twin Birth Rate
The 2007 twin birth rate was 32.2 per 1,000. This remained unchanged from 2005 and 2006.
The number of live births in twin deliveries rose 1.3 percent between 2006 and 2007 to 138,961 births. This number has more than doubled since 1980 (from 68,339).
- 137,085 twins were born in 2006
- The twin birth rate in 2006 was 32.2 per 1,000 births
Higher Order Multiples
Overall, the rate of triplet and higher order multiple births (quadruplets, quintuplets, sextuplets and septuplets) continued to decrease in 2007. The 2006 rate was 148.9 per 100,000 births compared to 153.5 in 2006, 161.8 in 2005 and 176.9 in 2004. However, while the number of triplets decreased (5,967 down from 6,118 in 2006), the number of quadruplet and higher births actually increased. (369 quads in 2007, but only 355 in 2006; 91 quints or higher in 2007, but only 67 in 2006.)
In 2007, the number of higher order multiple deliveries were:
- 5,967 triplets
- 369 quadruplets
- 91 quintuplets
- 0 sextuplets or septuplets
Multiple Birth Death Rates
Twins are five times more likely than singletons to die within a month of birth. Triplets are nearly 15 times more likely to die within a month of birth. (From 2005 data.)
Twinning Rates by Race
Twinning rates were essentially unchagned among the three largest racial/origin groups:
- Non-Hispanic White: 36.2 per 1,000
- Non-Hispanic Black: 36.8 per 1,000
- Hispanic: 22.2 per 1,000
Impact of Fertility Treatments
Assisted reproducive therapies (including in vitro, ovulation-inducing drugs and artificial insemination) account for 17 percent of all twins and 40 percent of all triplets born in 2007.
- 17 percent of twins are the result of fertility treatments.
- 40 percent of triplets are the result of fertility treatments.
Maternal Age Factors
Older women are much more likely to give birth to twins or triplets. One of every five births to women 45 years of age and older was born in twin delivery compated with less than two of every 100 births to teenage mothers.
- 20 percent of births to women over age 45 were twins.
- Only 2 percent of teen mothers had twins.
Preterm Birth Rates
A trend towards shorter pregnancies with multiples was observed. The percentage of twins delivered preterm (prior to 37 weeks) rose to 60.4% in 2006. This compares to 11.1% for single birth babies.
In 2007, multiples were more likely to be born small. More than half (57 percent) of all twins and nearly all triplets (96 percent) were identified as LBW (low birth weight) babies, as compared to 6 percent of singleton babies.
- Less than 40% of twins were born at 37 weeks or later.
- More than 12% were born prior to 32 weeks gestation.
- 36.33% of triplets were born prior to 32 weeks.
- About 80% of quads and higher were born befoer 32 weeks.
Highest and Lowest Multiple Birth Rates By State
For the years 2005- 2007, twins accounted for more than 4 percent of all births (more than 40 per 1,000) in Massachusetts, Connecticut and New Jersey. New Jersey, Nebraska and Massachusetts also recorded the highest rates of higher order multiple birth (triplets or more). The lowest rates were reported in New Mexico.
- States with the highest multiple birth rates are Connecticut, Massachusetts and New Jersey.
- State with the lowest rate is New Mexico.
- The highest triplet/+ birth rates were seen in Massachusetts, Nebraska, Connecticut, North Dakota and New Jersey.
- The states with the lowest rate were Alaska, Montana, Mississippi, District of Columbia, Hawaii, Arkansas and Oklahoma.
Source: National Vital Statistics Reports, Vol 58. No. 24, August 9, 2010
|U.S. Multiple Birth Rates 1995 - 2006|
|Year||Twins||Triplets||Quadruplets||Quintuplets or More||Twin Birth Rate per 1,000 total births||Triplet Birth Rate (per 100,000 total births)||Quadruplet and Higher Birth Rate (per 100,000 total births)|