In 1980 one in every 53 babies born in the United States was a twin. That rate has jumped to one in every 30 babies born in 2009.
Though an increase in maternal age is partly responsible for the trend, experts suggest that the rise in fertility treatments also plays a role. Approximately ⅓ of the rise is due to maternal age, while the remaining ⅔ is due to fertility treatments.
It’s estimated that 12% of all women have undergone some form of fertility treatment.
The rates of multiples pregnancy (2 or more babies) has also increased: from 1 in 2,702 in 1980 to 1 in 651 babies in 2009.
These findings are significant, as multiples pregnancies and births are associated with greater morbidity and mortality risks to both mother and baby and higher healthcare costs.