Twin and Multiple Birth Rate

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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)
2007	138,961	5,967	369	9`	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