Odds or Chances of Having Twins

What are the odds or chances of having twins?

The chances of having twins in 2003 was 3.1% or 1 in 32. The odds of having twins naturally was 2.11% or 1 in 47. The probability of having twins overall has risen drastically since 1980 when it was 1.89% or 1 in 53. So the chances of conceiving twins in 2003 rose 67% from 1980. This drastic increase in twin birth rate has been widely attributed to women waiting longer to conceive, the use of fertility drugs, and the use of in vitro fertilization(IVF).

A study done in the year 2000 estimated that approximately 67% of all twins were conceived without the use of IVF or fertility drugs such as Clomid.

The chance of having identical twins is approximately 1 in 250 or 0.4%. Historical twin statistics show that identical twins made up roughly 33% of all twin births. Currently only about 12% of all twin births are identical twins. The use of fertility drugs or in vitro fertilization does not increase the probability of having identical twins.

So what are some of the ways to increase the chances of having twins? As mentioned above, the use of fertility drugs can increase the odds of having twins to as high as 20% or 1 in 5. In vitro fertilization has a 25% chance of having twins or 1 in 4. In 1980, the majority(65%) of twins were conceived from a mother ages 20-29.

Year	Births	Twins	Triplets or More
2003	4,089,950	128,665	7,663
2002	4,021,726	125,134	7,401
1997	3,880,894	104,137	6,737
1996	3,891,494	100,750	5,939
1995	3,899,589	96,736	4,973
1994	3,952,767	97,064	4,594
1993	4,000,240	96,445	4,168
1992	4,065,014	95,372	3,883
1991	4,110,907	94,779	3,346
1990	4,158,212	93,865	3,028
1989	4,040,958	90,118	2,798
1988	3,909,510	85,315	2,385
1987	3,809,394	81,778	2,139
1986	3,756,547	79,485	1,814
1985	3,760,561	77,102	1,925
1984	3,669,141	72,949	1,653
1983	3,638,933	72,287	1,575
1982	3,680,537	71,631	1,484
1981	3,629,238	70,049	1,385
1980	3,612,258	68,339	1,337

Source: US Census Bureau