what factors may exist to aid children who were exposed to cocaine in utero. Whether the effects of PCE are increased once children reach adolescence is unknown, as is whether the neural rewiring that occurs during this developmental period attenuates the effects. A review of 27 studies performed between 2006 and 2012 found that cognitive development was mildly to moderately affected in PCE adolescents, but how important these effects were in practical terms was unclear. Unlike fetal alcohol syndrome, no set of characteristics has been discovered that results uniquely from cocaine exposure in utero. Cocaine exposure in utero may affect the structure and function of the brain, predisposing children to developmental problems later, or these effects may be explained by children of crack-using mothers being at higher risk for domestic violence, deadbeat parenting, and maternal depression. When researchers are able to identify effects of PCE, they are typically small. Pregnancy and birth Studies have found after controlling for other factors that some effects are present in pregnancies involving cocaine: abruptio placenta, prematurity, low birth weight, and small size compared to babies of the same gestational time. PCE newborns have smaller heads and shorter bodies. PCE effects are more severe when the amounts of cocaine are greater. As many as 17–27% of cocaine-using pregnant women deliver prematurely. In association with prematurity, growth in the womb is reduced, and low birth weight is connected to PCE. Also, some data associate spontaneous abortion with cocaine use. Cocaine reduces the appetite and has been linked with reduced maternal weight gain during pregnancy; in addition, constriction of the blood vessels may further limit supply of nutrients to the fetus. Using cocaine while pregnant also heightens the chances of maternal and fetal vitamin deficiencies, respiratory distress syndrome for the baby, and infarction of the bowels. Early reports found that cocaine-exposed babies were at high risk for sudden infant death syndrome; however, by itself, cocaine exposure during fetal development has not subsequently been identified as a risk factor for the syndrome. Some PCE children experience hypertonia (excessive muscle tone), and reduced reflexes and motor function have been found in babies four to six weeks old. While newborns who were exposed prenatally to drugs such as barbiturates or heroin frequently have symptoms of drug withdrawal (neonatal abstinence syndrome), this does not happen with babies exposed to crack in utero; at least, such symptoms are difficult to separate in