Initially, claims about crack babies were based primarily on studies of women who used or were addicted to crack during pregnancy. A study in New York City in 1989 compared the outcomes of 44 newborns to women who used crack during pregnancy to those in a control group. The control group and the group whose mothers used crack during pregnancy had similar infant characteristics. The number of low birth weight babies and the number of premature babies were not more than in the control group, leading the authors to conclude that any effect of crack on fetal growth was not great. A second study in 1989 examined the outcomes of 497 newborns and concluded that males born to women who used crack during pregnancy had a slightly lower mean gestational age, higher rates of low birth weight, and were more likely to come from a lower socioeconomic class than were males born to women with a negative urine test for cocaine. However, the groups were similar in other outcomes such as the percentage of birth defects.
A later study of 99 newborns in New York City from 1994-1997, as well as studies in Florida and New Mexico, did not show any effects of crack on birth weight or gestational age; instead, they found no effects on adverse outcomes of children exposed to crack in utero. However, they found higher rates in cocaine-positive women of low birth weight and premature infants, suggesting that cocaine affected intrauterine growth. They also found an increased rate of respiratory distress amongst cocaine-positive women and premature infants. Two other studies, one of children born in Indiana and one of children born in San Francisco, have also found no long-term effects of in utero cocaine exposure on children; they found no effect on infant death rate, birth defects, or IQ when they followed the children up.
The 1992-1993 National Health and Nutrition Examination Survey (NHANES) assessed the association between substance exposure and low birth weight. The survey included 641 children, including 13 who were cocaine positive, nine of whom were born preterm. Researchers found no difference in birth weight between babies born to women with prenatal cocaine exposure and babies born to women without cocaine exposure. The study concluded that "the literature does not support the suggestion that crack is associated with lower birth weight or prematurity". d2c66b5586