Pregnant women who consume one or two drinks a week may not cause any harm to their fetuses.
Research showed that children born to light drinkers had similar cognitive test scores and levels of behavioral difficulties as children born to mothers who stopped drinking during pregnancy.
"There appears to be no increased risk of negative impacts of light drinking in pregnancy on behavioral or cognitive development in 7-year-old children," co-author Yvonne Kelly, co-director of the ESRC International Centre for Lifecourse Studies (ICLS) at University College London, said in a press release.
The Centers for Disease Control and Prevention state that drinking alcohol during pregnancy can lead to birth defects and disabilities in children called fetal alcohol spectrum disorders (FASD). They are some of the most preventable birth defects and developmental disabilities. The CDC also points out that there is no amount of alcohol that is safe to drink while pregnant, and all drinks with alcohol can hurt a fetus.
Currently about one out of 13 pregnant women admits to using alcohol, according to the CDC.
The study authors point out, however, that while high levels of drinking have been linked to birth defects, not many studies have been done on lighter drinkers. To determine whether low levels of alcohol consumption had an effect, researchers looked at information from 10,534 7-year-olds who were enrolled in the Millennium Cohort Study, a U.K. study of infants born between 2000 and 2002. They visited the subjects at home, as well as interviewed the subjects' parents and teachers and gave them questionnaires to fill out about the child's social and emotional behavior.
The study group was just split up into children whose mothers who never drank (12.7 percent), children whose mothers who drank but not during pregnancy (57.1 percent), children whose mothers were light drinkers during pregnancy (23.1 percent) and children whose mothers drank more when they were pregnant (7.2 percent). The researchers focused on light drinkers and mothers who did not drink during pregnancy.
Children who were born to light drinkers -- meaning up to two drinks a week -- had higher but not significantly different cognitive scores compared to kids whose mothers who stopped drinking while pregnant. In fact, boys were shown to have slightly higher reading and special skills if they were born to mothers who had low levels of drinking.
As for behavioral problems, there was also no statistically significant differences between the groups, though boys were shown to have fewer behavioral problems.
"We need to understand more about how children's environments influence their behavioral and intellectual development. While we have followed these children for the first seven years of their lives, further research is needed to detect whether any adverse effects of low levels of alcohol consumption in pregnancy emerge later in childhood," Kelly said.
Linda Geddes, author of the pregnancy book "Bumpology," told the BBC that the new research could help women decide if they want to drink while pregnant.
"A lot of women are conflicted -- they know their mothers had a little to drink while pregnant with them, and they see friends and relatives drinking -- they may think the occasional drink is OK, but they also know the absolute safest thing to do is not to drink at all as the evidence is limited and they want to do the best by their babies," she said. "So this research is very reassuring for pregnant women - it is probably OK to have a glass or two."
Dr. Keith Eddleman, director of obstetrics at the Mount Sinai Medical Center in New York City, said to HealthDay that the new information makes sense with what other research has shown.
"Doctors have also known that an occasional drink during pregnancy is probably not a problem for your baby, especially if it is after the first trimester," he said. "This is based on the observation that the incidence of Fetal Alcohol Syndrome in countries where light alcohol consumption with dinner is commonplace and is no different from the incidence of the same disorder in countries where any alcohol consumption during pregnancy is considered taboo."
But he warned that doctors are still unsure how much alcohol is safe for the fetus.
"The problem is that no one knows the exact amount of alcohol consumption that is safe, so many doctors in this country choose a conservative approach and tell their patients not to drink any alcohol," he said.
The study appeared in BJOG: An International Journal of Obstetrics and Gynaecology on April 17.