How does alcohol affect pregnancy?

Fetal Alcohol Syndrome

Fetal alcohol syndrome (FAS) in children is the most widely recognized consequence of alcohol use during pregnancy. The syndrome was first recognized in the late 1960s as a pattern of physical abnormalities and mental impairment in children of alcoholic women.

Since the 1960s, other terms have been developed to encompass the broad spectrum of milder disorders associated with the effects of alcohol use on the fetus during pregnancy. These terms include fetal alcohol effects (FAE), fetal alcohol spectrum disorders (FASD), and alcohol-related neurological disorders.

According to the CDC, as of 2015, FAS affects approximately 0.2 to 1.5 infants for every 1,000 live births of mothers who drink heavily while pregnant. The estimates of children with neurological impairment from prenatal alcohol exposure (not classified as FAS) are much higher. The statistics on the numbers of children with FAS may be underestimates, because the diagnosis of FASD is largely dependent on disclosure from the mother of her own alcohol abuse. Thus, the diagnosis of FAS is difficult to make and is determined primarily through reports of the mother’s alcohol use during pregnancy in conjunction with a group of identifiable abnormalities in the child. The condition is characterized in a child by abnormal prenatal and postnatal growth, dysmorphic facial features, and central nervous system damage.

Alcohol use by pregnant women has been associated with growth deficiencies in both the fetus and the child after birth. Newborns have lower birth weights, and children with FAS demonstrate growth retardation even with sufficient nutrition. Weight and height remains in the lower one-tenth percentile for the child’s age group. Additionally, the child may have a low weight-to-height ratio and a short stature.

There are characteristic abnormal facial features in children with FAS, most noticeably small head size. Also present is maxillary hypoplasia, the underdevelopment of the jawbones that, when combined with an underdeveloped midface, gives the illusion of a protruding lower jaw. This may also be accompanied by a small separation between the upper and lower eyelids (palpebral fissures); a small, flat, upturned nose; thin upper lip; and characteristically folded “railroad track” ears. These facial features may become less obvious as the child matures.

Neurological deficiencies are the most severe consequence of FAS. Fetuses of women who drink heavily have been found to have a lower prenatal cranial-to-body growth ratio, with brain abnormalities continuing throughout early childhood. It is believed that every episode of consumption of two or more alcoholic drinks by the pregnant woman leads to the death of a quantity of fetal brain cells. Children with FAS generally have IQs about ten points lower than average; those with the most extreme FAS symptomology can have IQs of 60 to 70. Delayed speech and speech and language difficulties may be present throughout childhood.

Maternal alcohol use during pregnancy has been associated with attention deficit hyperactivity disorder (ADHD) in children, with the degree of severity of the ADHD directly related to the amount of alcohol consumed by the mother while pregnant. Impaired or delayed development of fine motor skills has also been observed in toddlers with FAS. Psychiatric disorders such as substance abuse, paranoia, personality disorder, aggressiveness, and behavioral dysfunction occur at increased rates in children with FAS. Unlike the abnormal facial features that improve as the child matures, neurological deficiencies persist into adulthood and throughout life.

Less apparent effects of maternal alcohol abuse on the child after birth include abnormalities of the hand. The pinky finger is bent inward toward the other fingers, and the upper crease of the palm is prominent, ending between the index and ring fingers. Other possible symptoms of FAS are cardiac defects and excessive hair growth. Various types of hearing loss have also been attributed to FAS and may contribute to the developmental and social delays that children with FAS often experience.

The manifestations of FAS symptoms are highly variable among children and dependent upon the amount of alcohol consumed by the mother while pregnant. Relationships have been observed between the amount and frequency of alcohol consumed and the gestational age of the fetus. The first six weeks are critical to embryonic development, as are the last few months of pregnancy, when the fetus undergoes a period of extensive growth. Therefore, alcohol consumption during these periods of pregnancy poses a higher risk to the fetus.

Binge drinking appears to be particularly deleterious to the fetus, as it is exposed to a high level of alcohol. During binge drinking, the pregnant woman’s liver takes longer to metabolize the large amount of alcohol, thereby also exposing the fetus to alcohol for an extended time.

Other factors may influence the severity of FAS symptoms exhibited by a child. It is theorized that the unique sensitivity of the pregnant woman to alcohol may moderate the effects of alcohol on the developing fetus. Variations in genes have been identified that influence the inclination to abuse alcohol, the rate of alcohol metabolism, and the tendency to develop FAS. Other factors present during pregnancy, such as maternal age, use of other drugs, nutrition, and even birth order, may influence the severity of FAS symptoms.

Prevention

Because no level of alcohol consumption by pregnant women has been determined to be safe for the developing fetus, the US surgeon general has recommended that women who are pregnant or intend to become pregnant in the near future, and those who are not using birth control, abstain from drinking alcohol entirely. This guidance is based on statistics showing that many pregnancies are unintentional, and women may drink alcohol before they realize they are pregnant.

The early weeks of pregnancy, including the time from conception to recognition of the first missed menstrual period, are critical to neurological development. Although alcohol use has been shown to decline after a woman realizes she is pregnant, the use of any alcohol during this time may be especially harmful to the embryo.

FAS is caused only by alcohol consumption by pregnant women and is a completely preventable cause of birth defects. Although FAS is not hereditary, the tendency to abuse alcohol may be. Health care providers can perform alcohol screening as part of routine prenatal care and can provide alcohol abuse information for their patients.

Alcohol use in the three months prior to pregnancy is also a good predictor of the pattern of alcohol use during the first three months of pregnancy. This information can be used to provide pregnant women with information on early intervention and abstinence programs. Women at high risk for alcohol abuse during pregnancy, however, frequently do not receive adequate prenatal care.

Bibliography

Centers for Disease Control and Prevention. “A 2005 Message to Women from the US Surgeon General: Advisory on Alcohol Use in Pregnancy.” Centers for Disease Control and Prevention. CDC, 2005. Web. 22 Mar. 2012.

Ethen, Mary K., et al. “Alcohol Consumption by Women Before and During Pregnancy.” Maternal and Child Health Journal 13 (2009): 274–85. Print.

"Fetal Alcohol Spectrum Disorders (FASDs): Data and Statistics." Centers for Disease Control and Prevention. CDC, 24 Sept. 2015. Web. 28 Oct. 2015.

Gray, Ron, Raja A. S. Mukherjee, and Michael Rutter. “Alcohol Consumption During Pregnancy and Its Known Effects on Neurodevelopment: What Is Known and What Remains Uncertain.” Addiction 104 (2009): 1270–73. Print.

O’Leary, Colleen M. “Fetal Alcohol Syndrome: Diagnosis, Epidemiology, and Developmental Outcomes.” Journal of Paediatric and Child Health 40 (2004): 2–7. Print.

Ornoy, Asher, and Zivanit Ergaz. “Alcohol Abuse in Pregnant Women: Effects on the Fetus and Newborn, Mode of Action and Maternal Treatment.” International Journal of Environmental Research and Public Health 7 (2010): 364–79. Print.

Wattendorf, Daniel J., and Maximillian Muenke. “Fetal Alcohol Spectrum Disorders.” American Family Physician 72 (2005): 279–82. Print.