A study in CDC’s Morbidity and Mortality Weekly Report last week reported that the birth rate for US teens aged 15-19 declined by 41% nationwide from 2006 to 2014. Disparities in teen birth rates also narrowed, with the birth ratio for Hispanic teens to white teens dropping from 2.9 to 2.2, and for black teens declining from 2.3 to 2.0. Because teen childbearing comes with a greater risk of negative health and economic consequences for mothers and children, this is good news for public health. But the persistence of disparities — by geography as well as by race and ethnicity — is still of concern.

Lisa Romero and CDC colleagues used data from the National Vital Statistics System to examine teen birth rates at the national, state, and county levels. Nationally, the teen birth rate was 25.4 per 1,000 teens in 2013-2014.

The five states with the lowest teen birth rates were:

• Massachusetts (11.3)
• New Hampshire (11.8)
• Connecticut (12.2)
• New Jersey (14)
• Vermont (14)

The five states with the highest rates were:

• West Virginia (38.3)
• Texas (39.4)
• Mississippi (40.3)
• New Mexico (40.5)
• Oklahoma (40.7)
• Arkansas (41.5)

Romero and her co-authors write about racial and ethnic disparities in the states:

The teen birth rate and racial/ethnic disparities for 2013–2014 ranged widely across states (Table). In some states, these disparities reflected very low rates of birth among white teens. For example, in New Jersey, the teen birth rate among whites (4.8) was well below the national rate for this group (18.0); whereas teen birth rates in this state among blacks (27.4) and Hispanics (31.3) were also lower than the national rates for these groups (blacks: 37.0; Hispanics: 39.8), they were approximately 6–7 fold higher than the rate for whites. In other states, disparities reflected birth rates for black and Hispanic teens that exceeded national rates for these groups. For example, in Nebraska, the birth rate for white teens (16.2) approximated the national rate, whereas rates for black and Hispanic teens (42.6 and 53.9, respectively) far exceeded the national rate for these groups. Finally, other states had smaller disparities, because teen birth rates were relatively high among all racial/ethnic groups. In Arkansas, for example, the teen birth rate was above the national rate for whites (37.7), blacks (54.6) and Hispanics (46.5).

At the county level, they found teen birth rates ranging from 3.1 to 119.0. Counties in the lowest quintile had a median rate of 14.6, while the median for counties in the highest quintile was 57.1. The highest-quintile counties were clustered in the south and southwest. The authors also report, “unemployment was higher, and education attainment and family income were lower in counties with higher teen birth rates.”

There are three main ways for teen birth rates to fall: Fewer teens can have intercourse; more teens can use contraception (or more-effective forms of contraception); and more teens who become pregnant can have abortions.

In an article about the CDC findings, the Washington Post’s Ariana Eunjung Cha considered some potential reasons for the decline in teen births. First, she notes, todays teen’s have better access to highly-effective forms of contraceptions, like long-acting injectables and implantable methods. Increasingly available broadband internet could help teens get information about such contraception, as well as relationship advice and abortion options, she suggests (I’m pretty sure this is the study she’s referencing). She also consulted experts about changes in teens’ sexual behavior. Cha writes:

[T]eens — despite their portrayal in popular TV and movies as uninhibited and acting only on hormones — are having less sex.

“There has been a change in social norms that has happened in the past 20 years, and the idea of not having sex or delaying sex is now something that can be okay,” said Bill Albert, chief program officer for the National Campaign to Prevent Teen and Unplanned Pregnancy.

Veronica Gomez-Lobo, director of pediatric gynecology at Children’s National Medical Center, said the trend of abstinence has been mostly among younger teens rather than older ones. While there’s not good data on why this is happening, she thinks of it as a “contagion” factor: So many teens are waiting to have sex, she suggests, that the peer pressure goes opposite to the way that it might have in the past.

Cha also references a study (probably this one) that found teen births dropped six percent in the 18 months following the first broadcasts of MTV’s reality show “16 and Pregnant.”

Given that the US abortion rate fell by 13% from 2008 to 2011 and that states have passed a slew of abortion restrictions over the past five years, an increase in abortions is unlikely to account for the drop in teen births. A recent study that reported a drop in US intended pregnancies from 2008 – 2011 found a likely explanation to be increased use of more-effective contraception. I noted at the time that statewide efforts in California, Colorado, and Iowa had increased access to long-acting reversible contraceptive (LARC) methods. In those states, the 2013-2014 teen birth rates were 21.9, 22.4, and 21, respectively, compared to the US average rate of 25.4.

The recipe for further reducing the overall teen pregnancy rate as well as racial and ethnic disparities will likely involve a combination of changing social norms while increasing access to contraception and to educational and economic opportunities. I hope the encouraging trends documented in this CDC report will continue.