Fetal alcohol spectrum disorders (FASDs) are a group of conditions that can occur in a person whose mother drank alcohol during pregnancy. Symptoms can include an abnormal appearance, short height, low body weight, small head size, poor coordination, behavioral problems, learning difficulties, and problems with hearing and sight. Those affected are more likely to have trouble with school, the legal system, alcohol, other drugs, and other areas of high risk. The several forms of the condition (in order of most severe to least severe) are: fetal alcohol syndrome (FAS), partial fetal alcohol syndrome (pFAS), alcohol-related birth defects (ARBD), static encephalopathy, alcohol-related neurodevelopmental disorder (ARND) and neurobehavioral disorder associated with prenatal alcohol exposure (ND-PAE). Some authorities accept only FAS as a diagnosis, seeing the evidence as inconclusive with respect to other types. Fetal alcohol spectrum disorders are caused by the mother's drinking alcohol while pregnant with the affected person. Surveys from the United States found that about 10% of pregnant women drank alcohol in the past month, and 20% to 30% drank at some point during the pregnancy. 3.6% of pregnant American women met criteria for an alcohol use disorder in a 2001 epidemiological study. The risk of FASD depends on the amount consumed, the frequency of consumption, and the points in pregnancy at which the alcohol is consumed. Other risk factors include the mother's older age, smoking, and poor diet. There is no known safe amount or time to drink alcohol during pregnancy. Although drinking small amounts does not cause facial abnormalities, it may cause behavioral problems. Alcohol crosses the blood–brain barrier and both directly and indirectly affects a developing fetus. Diagnosis is based on the signs and symptoms in the person. Fetal alcohol spectrum disorders are preventable by the mother's avoiding alcohol during pregnancy. For this reason, medical authorities recommend that women completely avoid drinking alcohol during pregnancy and while trying to conceive. Although the condition is permanent, treatment can improve outcomes. Interventions may include parent–child interaction therapy, efforts to modify child behavior, and drugs. FASD is estimated to affect between 1% and 5% of people in the United States and Western Europe. FAS is believed to occur in between 0.2 and 9 per 1,000 live births in the United States. In South Africa, some populations have rates as high as 9%. The negative effects of alcohol during pregnancy have been described since ancient times. The lifetime cost per