Twin and Multiple Birth Rate

Multiple birth rates for the United States in 2008 were released in December 2010. Here are some highlights:

Twin Birth Rate

The 2008 twin birth rate in the United States was 32.6 per 1,000. This is up very slightly from 2007, when the twin birth rate was 32.2 per 1,000. The twinning rate rose sharply between 1980 and 2004 (from 18.9 to 32.2) but has been fairly stable in the years since.

In 2008, 138,660 infants were born in twin deliveries. This number is down slightly from 2007 (138,961). This number mirrors the decrease in overall births in the United States, which declined about 2%.

• 138,660 twins were born in 2008
• The twin birth rate in 2008 was 32.6 per 1,000 births.

• 138,961 twins were born in 2007
• The twin birth rate in 2007 was 32.2 per 1,000 births.

• 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) was slightly decreased in 2008. The 2008 rate was 147.6 per 100,000 births compared to 148.9 in 2007, 153.5 in 2006, 161.8 in 2005 and 176.9 in 2004. The number of triplets born in 2008 decreased: 5,877 down from 5,967 in 2007 and 6,118 in 2006. The number of quadruplet and higher order multiple births also decreased. Quadruplets: 345 in 2008, down from 369 quads in 2007, but up from 355 in 2006. The number of quints (or higher) decreased almost by half: 46 born in 2008, down from 91 quints or higher in 2007, but only 67 in 2006.

In 2008, the number of higher order multiple deliveries were 6,268, the lowest number in more than a decade. The number of higher order multiple deliveries by type were:

• 5,877 triplets
• 345 quadruplets
• 46 quintuplets or higher

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

Among the three largest racial/origin groups in the United States, the twinning rates in 2008 are as follows:

• Non-Hispanic White: 36.6 per 1,000
• Non-Hispanic Black: 36.8 per 1,000
• Hispanic: 22.3 per 1,000

For triplets and other higher order multiples, the rates for 2008 are:

• Non-Hispanic White (198.1 per 100,000)
• Non-Hispanic Black 91.3 per 100,000
• Hispanic 80.1 per 100,000

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. In 2008, 6% of all births to women 40-44 years old, and 22% of births to women 45 or older was a twin, compared with less than 2% of births to teenage mothers.

• 22 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 in 2007. 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 2006- 2008, the state with the highest multiple birth rate (for twins, triplets and other multiple births) was New Jersey. The lowest twin birth rate was reported in New Mexico. The state with the lowest triplet+ birth rate is Alaska.

Source: National Vital Statistics Reports, Vol 58. No. 24, August 9, 2010

Click here for 2007 data.

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)
2008	138,660	5,877	345	46	32.6	147.6 (triplet+)	N/A
2007	138,961	5,967	369	91	32.2	138.2	10.7
2006	137,085	6,118	355	67	32.1	143.4	9.89
2005	133,122	6,208	418	68	32.2	150.0	11.7
2004	132,219	6,750	439	86	32.2	164.2	12.8
2003	128,665	7,100	468	85	31.5	173.8	13.5
2002	125,134	6,898	434	69	31.1	171.5	12.5
2001	121,246	6,885	501	85	30.1	171.0	14.6
2000	118,916	6,742	512	77	29.3	166.1	14.4
1999	114307	6,742	512	67	28.9	170.3	14.6
1998	110,670	6,919	627	79	28.1	175.5	17.9
1997	104,137	6,148	510	79	26.8	158.4	15.2
1996	100,750	5,298	560	81	25.9	136.1	16.5
1995	96,736	4,551	365	57	24.8	116.7	10.8