Twin births in United States has become quite common and recent data released by the US Centers for Disease Control and Prevention (CDC), has shown that the twin birth rate hit an all-time high of 33.9 twins per 1,000 births.

The CDC experts said that although the rate of twin birth has reached a record high but are up only .2 from 2013. In 2013 the twin birth rate was 33.7 twins per 1,000 births.

The trend of twin birth in past few decades has been dramatic, said experts. The twinning rate rose 76% from 1980 to 2009, the report said.

As per the report, this trend has been due to highly improved fertility therapies, such as ovulation-inducing drugs, and assisted reproductive techniques like as in-vitro fertilization.

In case of In-vitro fertilization (IVF), conceiving twins has become more common because doctors implant more than one embryo. And when there are multiple embryos, the chances of pregnancy increases and so does the chances of having twins.

A Newsweek investigation in November 2014 revealed that twins that are conceived through IVF are more likely to be born early than single babies. Another report said, “Infants born in twin and triplet deliveries are at higher risk of adverse birth outcomes compared with singletons. In 2014 more than one of every two twins and more than nine of every ten triplets were born preterm or low birthweight”.

In 2014, there were 3,988,076 registered births in United States, almost 50,000 more births than in 2013. The majority of these babies were first or second children for a mother, almost 21,589 were the eighth (or over) child, showed report.