Effects of Drinking in the First Few Weeks of Pregnancy

Young couple raising a toast with announcement of pregnancy to family during outside family lunch

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If you were consuming alcohol in the weeks before you learned that you were pregnant, you might be worried about the possible consequences. The early weeks of pregnancy are critical to embryo development but the research on the effect of drinking alcohol during this period is conflicting.

Research on Alcohol in Early Pregnancy

Some studies have suggested that consuming alcohol during the first few weeks of pregnancy can harm the development of the fetus. However, other studies have suggested that drinking during the early days of pregnancy does not harm a developing fetus.

Research has also provided evidence that it's a person's pattern of drinking (for example, having one drink per day as opposed to binge drinking) that wields the most influence on the effect alcohol consumption has on fetal development.

The Centers for Disease Control and Prevention (CDC) states that no amount of alcohol is safe during pregnancy.

Key Time of Development

Body systems and organs are developing during the embryonic stage of pregnancy which begins at fertilization and lasts through week 8.

The heart, central nervous system, eyes, arms, and legs of the fetus are developing during the first four weeks of pregnancy—when many people are not yet aware that they are pregnant. These developing organ systems are more vulnerable to damage during the early stages of development.

Drinking Pattern Is Significant

Over the years, studies of fetal alcohol syndrome have found that a pregnant person's pattern of drinking has the greatest effect on a fetus. The most dangerous drinking patterns are chronic drinking, heavy drinking, and binge drinking.

The pattern and timing of prenatal alcohol use can greatly influence the impact of adverse effects on the fetus, according to the CDC.

Study Finds No Adverse Effects

A study of 5,628 pregnant women in England, Ireland, New Zealand, and Australia found that women who drank during the early weeks of pregnancy were not at an increased risk for premature birth or low birth weight babies. The women also did not have an increased risk for high blood pressure complications during pregnancy.

This study was met with a great deal of controversy when it was published in October 2013.

The rates of premature birth and low-birth-weight babies for women who reported having seven or more drinks per week (about 15% of the group) were the same as the rates in women who did not drink.

Is Low-Level Drinking Dangerous?

A study of 1,264 pregnant women conducted a year later by the University of Leeds in England found that women who drank even low-level amounts of alcohol during the first weeks of pregnancy were at risk for having premature or unexpectedly small babies.

Women who drank as few as two drinks a week had a greater risk of premature birth and low-weight birth than women who did not drink.

A Word From Verywell

It's unclear how alcohol consumed during early pregnancy will affect a fetus, but most health organizations advise people to stop drinking alcohol as soon as they intend to become pregnant or as soon as they find out that they are pregnant.

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  1. Johns Hopkins Medicine. The first trimester.

  2. Nykjaer, C. et al Maternal Alcohol Intake Prior to and During Pregnancy and Risk of Adverse Birth Outcomes: evidence from a British cohort. J Epidemiol Community Health. 2014;68:542-549. doi:10.1136/jech-2013-202934

  3. The Centers for Disease Control and Prevention (CDC). Alcohol Use in Pregnancy. Updated April 30, 2020.

  4. Centers for Disease Control and Prevention. Fetal development chart.

  5. McCarthy, FP, et al Association Between Maternal Alcohol Consumption in Early Pregnancy and Pregnancy Outcomes. Obstet Gynecol. 2013;122(4):830-837. doi:10.1097/AOG.0b013e3182a6b226

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