According to a report from the U.S. Centers for Disease Control and Prevention's National Center for Health Statistics, the twin birth rate in the country is at 33.9 for every 1,000 births, a record high in 2014.

This rate is up from the 33.7 for every 1,000 recorded in 2013 and is almost double of the rate 18.9 twins for every 1,000 logged in 1980. The National Vital Statistics Report "Births: Final Data for 2014" also showed, however, that triplets and higher-order births have declined for the report period, registering 113.5 cases for every 100,000 in 2014 compared to 119.5 for every 100,000 in 2013. The 2014 birth rate is not only down over 40 percent from the peak rate in 1998 but is also the lowest in 20 years. Back then, the triplet and higher-order birth rate was at 193.5 cases for every 100,000.

There are several factors contributing to the rise in twin births but two of the possible reasons, according to the researchers, are that more women are taking advantage of fertility treatments and having children at older ages. Based on other studies, having children at a later age increases the chances of having twins.

Additionally, tweaks in fertility treatments, like implanting fewer embryos, may have also contributed to the decline in triplet and higher-order births.

While it has been established that more women are giving birth at older ages, the report also saw a record low for the number of women giving birth while in their 20s. From 2013 to 2014, the researchers saw a spike in women giving birth not only in their late 20s and 30s but up to their early 40s as well.

On average, the age at which a woman gives birth to her first child also rose slightly, going from 26.0 to 26.3 years old. This coincided with a drop in teenage births, also an all-time low at 24.2 births for every 1,000 for teenagers between 15 and 19 years old in 2014. In 2013, the birth rate was at 26.5 births for every 1,000 from the same age group.

In 2014, 3.99 million babies were born in America. This is up by about 1 percent from 2013's 3.93 million babies.

Photo: Donnie Ray Jones | Flickr