Drug & Alcohol Related Birth Defects

Substance use during pregnancy

/ Author:  / Reviewed by: Joseph V. Madia, MD

The National Institute of Child Health & Human Development (NICHD) has released numerous studies investigating the outcomes of alcohol and drug use during pregnancy.

According to data from the Centers for Disease Control and Prevention (CDC), one in 33 babies are born with a birth defect. Birth defects are the leading cause of infant death. They are commonly the result of the baby’s environment in which the mother is exposed to some toxin or hazard or from genetic factors.

The NICHD warns not only about the risks of taking illegal drugs, but also over-the-counter medications. Many are unsafe for women to take while pregnant.

According to the NICHD, women who are trying to become pregnant should avoid drugs and alcohol for up to 3 months before conception to promote a healthy pregnancy.

When a woman is pregnant, whatever she consumes—the baby consumes. There is no dilution from the mother’s system to the fetus.

Birth Defects from Alcohol

When birth defects like physical abnormalities, developmental delays and behavioral difficulties occur due to alcohol exposure they are categorized as fetal alcohol spectrum disorders (FASDs). More serious physical deformities and neurological damage cases qualify as fetal alcohol syndrome (FAS).

In studies performed by the division of epidemiology, statistics, and prevention research (DESPR) at the NICHD, consuming more than two ounces of alcohol per day during a pregnancy is considered ‘heavy’ drinking.

The NICHD gathered data on women who drank alcohol and smoked cigarettes from two months before getting pregnant through the first two months of their pregnancy. They looked at 1,355 drinking/smoking cases from 1999-2003 in California.

Out of this group, 701 children had orofacial clefts where the mouth, lip or roof of the mouth, are misshapen and not formed correctly. Neural tube defects (NTD) were present in 337 children, which is when the brain and spinal cord do not form completely. Spina bifida and anencephaly are the most common NTDs.

Spina bifida occurs when the fetus’ spinal column does not close like it is supposed to in the first month of fetal development. This lack of development leaves the spinal nerves open to damage and can lead to leg paralysis. Anencephaly occurs when the fetus’ brain doesn’t fully develop and usually results in death before or shortly after birth.

Conotruncal heart defects were present in 323 cases, which is when the major blood vessels leaving the heart and the heart’s chambers are not properly connected.

When the drinking cases were compared to 700 nondrinkers, the risk of developing NTDs were 2.1 times higher for the exposed children, and 2.6 times higher for developing orofacial clefts.

Drug Related Birth Defects

In a 2010 study, Barry Lester, PhD, director of psychiatry and human behavior and pediatrics at Warren Alpert Medical School of Brown University, led an investigation into the effects of cocaine usage during pregnancy on later childhood stress response.

A total of 743 11-year-old children (320 who were prenatally exposed to cocaine and 423 in the control group) were followed from birth. Researchers took saliva samples to measure each child’s cortisol levels at rest and then also after inducing psychological stress.

Children exposed to cocaine in the womb had a stunted cortisol response to stress. Cortisol is one of the body’s natural response tools to stress. It is necessary for proper physical and emotional function and its absence or lack could result in both physical and mental health problems.

Surveys administered by the Obstetric and Pediatric Pharmacology Branch have shown results that indicate two-thirds of pregnant women take up to four drugs, including over-the-counter drugs, while pregnant or in labor.

What Causes the Defects?

Scientists have some idea of what can cause certain birth defects, but little is known about why exactly alcohol does damage. The theory that alcohol interfered with the absorption of oxygen by constricting blood vessels to the fetus was proven wrong by the NICHD.

Another study done at the University of Chile looked at the effects of alcohol on growth hormones both pre- and postnatal. This study looked at 69 children of drinking mothers compared to 83 children of nondrinking mothers. They measured each child for different insulin-like growth hormones at 1 month, 1, 2, 3, 4, and 5 years of age.

The growth hormones were different enough in the two groups over time to perhaps explain why low-birth weight and stunted height can result from prenatal alcohol exposure.

This is a good start, but it doesn’t explain everything. Further research is necessary to fully understand all of the reasons associated with the many FASDs and drug-related birth defects that can occur.

The take away message released by the NICHD’s significant research concluded that preconception through the end of breast feeding is a time that drugs, including over-the-counter medications, and alcohol must be avoided for the sake of the baby’s health.

Review Date: 
July 10, 2012