Drinking in Early Pregnancy

Does current science support a zero tolerance policy?

Pregnant woman with glass of red wine
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It has become almost a de facto rule: you do not drink during pregnancy. So vehemently has this message been drilled into the public consciousness that it leaves the impression that a little alcohol, even in the early stages of pregnancy, places a fetus at a significant risk of birth defects.

But is this actually so? And what if you were a drinker — even a heavy drinker — at the time you became pregnant?

Has the damage already been done? When does an occasional drink become a genuine health concern?

Zero Tolerance in the Public Health Message

The first step is to take a deep breath. The vehemence of the public health message, while well intentioned, can sometimes leave a woman feeling that even discussing the subject of alcohol and pregnancy is forbidden. This shouldn't be the case.

The simple fact is that there is no way to where the line is between safe and unsafe is. It is all highly individual in the same way that a person's response to alcohol is highly individual.

But let's put aside the public health message for one moment and look at what the current evidence actually tells us.

Drinking During Early Pregnancy

While it is well known that drinking during pregnancy can lead to the development of fetal alcohol syndrome (FAS) while increasing the risk of miscarriage, birth defects, and other health complications, an occasional drink appears to have less effect during the first trimester than some might assume.

As 2013 study from the University of Adelaide compared birth outcomes in five thousand six hundred and twenty-eight women in England, Ireland, Australia, and New Zealand who were pregnant for the first time between 2004 and 2011. In terms of alcohol consumption, the authors found that:

  • More than half reported drinking alcohol during the first trimester.
  • Thirty-four percent reported at least one binge episode during the first trimester.
  • Twenty-five percent said that they drank three to seven drinks per week.
  • Nineteen percent said that they had one to two drinks per week.  
  • Fifteen reported having eight to fourteen drinks per week.
  • Five percent consumed more than fourteen drinks per week.

(A drink was defined as a glass of wine or less than a twelve-ounce bottle of beer.)

In comparing the participants, both drinkers and non-drinkers, the researchers reported that there was no association between alcohol consumption before fifteen weeks and the number adverse factors at birth. These included low birth weight, small birth size, preterm birth, and preeclampsia (a potentially life-threatening condition in which a pregnant woman develops high blood pressure).

What the study did not show, of course, was whether drinking caused damage to the baby that we cannot see, specifically the impairment of mental function. And this is where things get a little fuzzier.

Patterns of Drinking During the First Trimester

According to an analysis from the Texas A&M University Health Science Center, which extrapolated data from both human and animal trials, the patterns of drinking may be more of a factor in fetal brain developmental problems than the practice of drinking itself.

 

Even during early pregnancy, binge drinking (defined as having more than four drinks within two hours) increases the blood alcohol concentration (BAC) far beyond what would be seen in a casual drinker. This exposes the developing fetus to same levels of alcohol that cause hangover in adults but at a stage where the brain is developing and has less capacity for self-repair.

Long-term studies in humans have confirmed that children of binge-drinking mothers have especially severe cognitive and behavioral problems compared to children of non-binge-drinking mothers.

While this may suggest that mothers who are non-binge drinker are "safe" (or that binge-drinking mothers can continue drinking without further consequence), the research suggests just the opposite.

 

According to the study, early alcohol exposure may have as much ill effect on fetal brain development as alcohol exposure throughout pregnancy. Moreover, the persistent of drinking is associated with a worsening of defects in the second trimester, resulting in a loss of plasticity (ability to change and develop) of fetal brain tissue.

What All of This Tell Us

The bottom line is this: we don't know for sure where the line is between acceptable and non-acceptable drinking during pregnancy. Complicating matters further is the fact that the threshold can vary from person to person, with some women having more of the enzymes needed to break down alcohol than others. For this latter group, the blood alcohol concentration may end up being far higher with only one drink.

Moreover, the choice of drink plays a key role in determining how much or little alcohol your baby is exposed to. It's one thing to have a glass of wine or beer; it's another to have a shot of liquor which can have twenty times more alcohol per serving.

But this doesn't mean you should panic if you're a drinker and suddenly find yourself pregnant. A baby's major organs will don't begin to develop until around the third week of pregnancy, giving you a little cushion before cells begin to specialize and form fetal brain tissue. (Please note that this is around the time a pregnancy test might be done if you missed your period.)

If you have a history of drinking or enjoy the occasional drink every now and then, be honest with your doctor or midwife during your prenatal visits. Don't minimize your alcohol intake or say you're drinking less than you are. This is especially true if you find it hard to stop or cut back. Bending the facts to please your doctor or avoid consternation will help no one, including your baby.

Honesty, by contrast, allows you to make an informed judgment with full information based not on fear but on fact.  

Sources

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