Will One Drink Hurt the Baby?

Alcohol drinking during pregnancy debate continues

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) One of the common questions pregnant women might wonder is whether they can drink any alcohol at all while pregnant. One glass of wine? One sip? Will it hurt the baby?

A recent study looked at that question in terms of children's cognitive skills and behavior. This study took into account a large range of possible factors that could affect the children's performance.

These researchers found that the children of women who drank one or two drinks a week or less did not appear to suffer any negative brain or behavior effects.

However, this study's findings are contrary to some previous research. The findings also do not mean women should have any drinks during pregnancy.

"Ask your OB/GYN about drinking alcohol."

The study, led by Yvonne Kelly, PhD, of the Department of Epidemiology and Public Health at University College London in the United Kingdom, looked at whether light drinking during pregnancy affected women's children at age 7.

The 10,534 children involved in this study are part of a long-term study that has involved home visits when the children were 9 months, 3 years, 5 years and 7 years old.

At each home visit, the researchers interviewed the mothers about their drinking habits (during and after pregnancy), their children's behavior, the family's socioeconomic circumstances, the family's demographics and the social environment of the child and family.

The researchers also assessed the children's cognitive skills using tests in reading, math and spatial skills when the kids were 7. The children's teachers also filled out mailed questionnaires about the children's behavior.

During the home visit when the children were 9 months old, the mothers described how often they drank alcohol while pregnant: every day, 5-6 days a week, 3-4 days a week, 1-2 days a week, 1-2 times a month, less than once a month or never.

Women who drank any alcohol each week were asked how many units they had each week, and women who drank less than twice a month were asked how much they drank during those times. A unit was defined as "half a pint of beer, a glass of wine or a single measure of spirit or liqueur."

Overall, 13 percent of the women never drank alcohol before, during or after pregnancy, and 57 percent did not drink alcohol during pregnancy but did after pregnancy.

Almost a quarter (23 percent) of the women were considered "light drinkers" who had one to two units of alcohol per week or per occasion (if less than once a week) while pregnant. Seven percent of the women drank more than twice a week while pregnant.

When the researchers analyzed the results of the cognitive tests and behavioral assessments, they took into account a wide number of variables that might affect the results besides the mother's alcohol intake during pregnancy. These included the following:

  • mother’s age
  • whether the pregnancy was planned
  • whether the mother smoked during pregnancy
  • whether the child was a first-born
  • ethnicity
  • single parent family
  • a combined score related to the mother's answers to questions on life satisfaction, relationship quality and social networks
  • number of children in the household
  • child’s age
  • the child's birth weight
  • highest level of the parents' education
  • family income
  • mother’s mental health
  • which discipline strategies the parents used (frequency of ignoring, smacking, shouting, sending to the ‘naughty chair’, removing treats, telling off and bribing)
  • how the mother rated her competence as a parent
  • how the mother rated the closeness of her relationship with her child
  • whether the mother currently drank alcohol
  • how frequently the child was read to
  • whether the child had regular bedtimes

Before adjusting for these variables, the researchers found that the children born to women who were light drinkers during pregnancy had slightly lower (better) behavior scores and slightly higher cognitive test scores than the children of moms who did not drink during pregnancy but did drink afterward.

After the researchers adjusted for those variables, the behavior scores evened out a bit and were no longer "statistically significant" except for the boys' behavior as rated by teachers.

Not being "statistically significant" means that the difference between the kids of light drinkers and the kids of non-drinkers was too small to determine whether those differences were related to the alcohol intake during pregnancy.

The difference in cognitive skills between the kids of light drinking pregnant moms and non-drinking pregnant moms also evened out after adjusting for variables, with one exception. The sons of women who were light drinkers during pregnancy still had slightly higher spatial and reading skills than the boys of women who didn't drink during pregnancy, though the differences were small.

"In this large, nationally representative study of 7-year-olds, there appeared to be no increased risk of a negative impact of light drinking in pregnancy on behavioral or cognitive development," the researchers wrote.

"Prior to statistical adjustment, children born to light drinkers appeared to have more favorable developmental profiles than children whose mothers did not drink during their pregnancies, but, after statistical adjustment, the differences largely disappeared," they wrote.

"Our findings from regression models and PSM support the suggestion that low levels of alcohol consumption during pregnancy are not linked to behavioral or cognitive problems during early to mid-childhood," they wrote.

However, these findings, from a single study, do not change the advice of OB/GYNs and certified nurse midwives to women.

"I am frequently asked about 'just one glass of wine on occasion' and I counsel patients that there are many factors that contribute to fetal alcohol syndrome and developmental deficits," said Jen Mushtaler, an OB/GYN in Austin, Texas, and a dailyRx expert.

"As we do not completely understand how this happens in utero, the American College on Obstetrics and Gynecology advises women to refrain from any alcohol consumption during pregnancy," she said.

Dr. Mushtaler suggests patients ask themselves a question to consider whether having one drink is okay.

"My advice to my patients is to ask themselves if anything were to go wrong, would they blame themselves and feel guilty," she said. "If the answer is yes, then the one glass of wine is not worth drinking."

The study was published April 17 in BJOG: An International Journal of Obstetrics and Gynaecology. The research was funded by the Economic and Social Research Council. The authors declared no conflicts of interest.

Reviewed by: 
Review Date: 
April 16, 2013
Last Updated:
December 30, 2013