The government has a message for women: If you're not using birth control, you shouldn't be drinking.
The Centers for Disease Control and Prevention, in a new report, warns that women who aren't using contraception and who are consuming alcohol are taking unacceptable risks. It estimates 3.3 million women in the US could be endangering the health of a potential child by having unprotected sex and continuing to drink.
Drinking while pregnant can cause children to be born with physical and mental disabilities, sometimes severe ones. The CDC's guidance is trying to prevent that.
But the guidance hits at the intersection of two controversies: whether pregnant women should drink alcohol at all, and whether all women, even those who don't expect or want to have a child, should take precautions in case they become pregnant.
The research is mixed on how much harm a few drinks early in pregnancy might do
It's not clear how many children in the US are born with fetal alcohol spectrum disorders, a range of physical and mental disabilities caused when a woman drinks during pregnancy. Estimates range from three in every 1,000 births to as many as one in five.
Doctors emphasize that no matter how common it is, fetal alcohol syndrome is a preventable disorder, and that genetic factors can play a role. The best way to avoid it is for a woman to abstain from drinking the moment she becomes pregnant (even if she doesn't know it yet) until after she gives birth. That's the firm consensus from the CDC, the American Academy of Pediatricians, and the American College of Obstetricians and Gynecologists.
A 2014 analysis of 34 studies found that binge drinking while pregnant — for women, more than four drinks in one sitting — could harm children's cognitive abilities later on, and that moderate drinking could lead to negative effects on children's behavior.
Fetal alcohol syndrome has a genetic component; not all children of women who drink develop it, and some children are born with it even if their mothers didn't drink much at all. Studies of children with fetal alcohol syndrome in Washington state found 14 percent were born to women who say they had about a drink per day or less.
Still, the evidence of how much harm an occasional drink will probably do is less clear. A 2010 longitudinal study in the United Kingdom found no evidence that light drinking during pregnancy led to differences in children's behavior or cognition at age 5.
For many women, that's translated into a belief that a little light drinking during pregnancy is an acceptable risk. About 10 percent of pregnant women report drinking, according to the CDC, and it's more common among women between ages 35 and 44 and those with college degrees.
Women who aren't pregnant are told to behave like they might be
More than one-third of births in the US are among women who didn't intend to get pregnant: About half of all pregnancies in the US are unplanned, and 60 percent of unplanned pregnancies are carried to term rather than aborted.
That's why the CDC recommends that women who aren't pregnant should still take precautions that could protect a developing fetus. The agency says all women between 15 and 44 should take folic acid, a supplement that can prevent birth defects early in pregnancy, even if they're using contraception.
The new recommendation to avoid alcohol is based on the same rationale. Women might be pregnant without realizing it, and continue drinking, for weeks. The CDC argues women should stop drinking as soon as they stop using birth control.
But the advice strikes a nerve because it appears to treat all women of childbearing age as potential mothers — regardless of whether they have any intention of getting pregnant or carrying a pregnancy to term.