Right around the point where women "seriously" mistimed their pregnancy (meaning that they wanted to have a baby eventually, but not within two years of when it ended up happening), their self-reported ratings of "trying" and "wanting" to avoid pregnancy intersect and diverge. This demonstrates a clear case of wanting one thing while practicing another, of these women not having the insight or the resources to act in accordance with their desires.

Of course it does require two people to get pregnant, and 18.3 percent of the women whose pregnancies fell under the categories of "unwanted" and "unprotected" reported that they chose not to use any form of birth control because their partners didn't want them to. Whether or not a woman thought the baby's father wanted the pregnancy also had a huge impact on how much she reported wanting the pregnancy: 7.9/10 if the father was on board, 2.7/10 if he was believed not to be.

There are 290,000 babies born each year to mothers who believed their coming into existence was a statistical improbability.

So, while 50 percent of all pregnancies in the U.S. are accidental (based on other research cited by the survey), a third of babies who are actually brought into the world were not, nine months earlier, planned for. And while, sure, life doesn't always go as planned, and a mother might decide she's ready even if she didn't think so beforehand, a surprise pregnancy means that she will probably be later in getting prenatal care and in changing her habits -- especially those that are drinking, smoking, and drug-related -- in response.



The survey shows, in fact, that twice the number of women whose pregnancies were unintentional as those who were trying to get pregnant failed to receive prenatal care during the first trimester. Mothers with unintended pregnancies were also more likely to smoke, and their babies were slightly more likely to have a low birthweight.

It was noted as well that 65 percent of deliveries of unintended pregnancies were paid for by Medicaid, as opposed to 35 percent of planned births.

Unintended pregnancies tend to occur to mothers with fewer resources to support the child, and therefore result in direct public health costs through Medicaid more often than intended pregnancies.

My freshman year of college, someone handed me a button that proclaimed, "Sex education is birth control." That's the first thing I thought of when I saw these numbers. Since 1982, the first year in which the National Survey of Family Growth was conducted, there has been no statistically significant change in the overall number of unintended births that occur each year. To bring this number down, a good first step might be the one that seems easiest to carry out.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.