Alcohol use by a pregnant woman may interfere with the development of her fetus. Newborns whose mothers are intoxicated during delivery can experience withdrawal symptoms, such as tremors and even seizures. It is likely that withdrawal also can occur during fetal development. Thus, the possibility exists that withdrawal by the pregnant woman may exacerbate alcohol's adverse effects on her fetus. One potential mechanism through which alcohol withdrawal might damage the fetus involves the receptor for the neurotransmitter glutamate (i.e., the N-methyl-D-aspartate [NMDA] receptor). This receptor plays a crucial role during neuronal development. Excessive activation of the NMDA receptor, which occurs during withdrawal, may lead to neuronal cell death. Animal studies suggest that these effects may contribute to behavioral deficits following prenatal exposure to alcohol.
KEY WORDS: fetal alcohol syndrome; AOD withdrawal syndrome; symptom; gestation; fetus; neonate; mother; prenatal alcohol exposure; heavy AOD use; binge AOD use; congenital anomaly; fetal development; central nervous system; NMDA receptors; cytolysis; cell growth and differentiation; teratogenesis; brain damage; AOD abstinence; animal model; literature review
A woman who drinks alcoholic beverages during pregnancy exposes not only herself but also her fetus to alcohol. Alcohol readily crosses the placenta; consequently, the blood alcohol levels (BAL's) of the fetus are similar to those of the mother. Likewise, if the woman suddenly abstains from alcohol, both she and her fetus may undergo withdrawal. This article briefly describes the withdrawal symptoms observed in pregnant women and newborns, discusses the birth defects associated with prenatal alcohol exposure, and explores the possibility that alcohol withdrawal (AW) may contribute to the adverse effects of prenatal alcohol exposure on fetal brain function and behavioral development.
WITHDRAWAL SYMPTOMS IN PREGNANT WOMEN AND NEWBORNS
Despite warning labels on alcoholic beverages and an increased awareness among the general population of alcohol's deleterious effects on the developing fetus, the women who are the heaviest alcohol abusers frequently do not change their drinking practices during pregnancy. Such women are at the greatest risk for giving birth to a child with alcohol-related problems. In the United States, approximately 3.3 percent of pregnant women are estimated to consume two or more drinks per day (Abel 1990).
One of the consequences of heavy alcohol use is the potential for experiencing withdrawal symptoms during periods of abstinence. Symptoms of mild to moderate withdrawal from alcohol may include tremors, sweating, stomach pain, anxiety, and sleep disturbances. Severe withdrawal symptoms may include delirium tremors and violent agitation (i.e., seizures). These effects may begin within hours of the last drink and may persist for several days. Various tranquilizers and sedatives, including alcohol itself, have been used to manage these symptoms (Thorp 1995).
When a pregnant woman undergoes AW, so does her fetus. To date, no studies have analyzed the symptoms and effects of withdrawal on fetuses in utero. However, researchers have studied withdrawal in newborns whose mothers were intoxicated during delivery. For example, Beattie (1986) reported the case of a newborn who had a BAL of more than 200 milligrams per deciliter (mg/dL) (i.e., over 0.2 percent1) and exhibited signs of AW-including tremors, irritability, frequent mouth movements, and vomiting-between 24 and 48 hours after delivery.
The onset of withdrawal symptoms in newborns may be delayed compared with adults, because alcohol metabolism in newborns is slower than in adults. Neonatal AW typically manifests itself as hyperexcitability of the central nervous system (CNS) and gastrointestinal symptoms. CNS hyperexcitability results in symptoms such as tremors, excessive muscle tension, irritability, increased respiratory rate, poor sleeping patterns, and increased sense of hearing (i. …