<unk>  (PCE), theorized in the 1970s, occurs when a pregnant woman uses<unk>  and thereby exposes her fetus to the drug. Babies whose mothers used<unk>  while pregnant supposedly have increased risk of several different health issues during growth and development. "Crack baby" was a term coined to describe children who were exposed to crack (freebase<unk>  in smokable form) as fetuses; the concept of the crack baby emerged in the US during the 1980s and 1990s in the midst of a crack epidemic. Other terms are<unk>  baby" and "crack kid". Early studies reported that people who had been exposed to crack in utero would be severely emotionally, mentally, and physically disabled; this belief became common in the scientific and lay communities. Fears were widespread that a generation of crack babies was going to put severe strain on society and social services as they grew up. Later studies failed to substantiate the findings of earlier ones that PCE has severe disabling consequences; these earlier studies had been methodologically flawed (e.g. with small sample sizes and confounding factors). Scientists have come to understand that the findings of the early studies may have been overstated. No specific disorders or conditions have been found to result for people whose mothers used<unk>  while pregnant. Studies focusing on children of six years and younger have not shown any direct, long-term effects of PCE on language, growth, or development as measured by test scores. PCE also appears to have little effect on infant growth. However, PCE is associated with premature birth, birth defects, attention deficit hyperactivity disorder, and other conditions. The effects of<unk>  on a fetus are thought to be similar to those of tobacco, and are less severe than those of alcohol. No scientific evidence has shown a difference in harm to a fetus between crack and powder<unk> . PCE is very difficult to study because it very rarely occurs in isolation; usually it coexists with a variety of other factors, which may confound a study's results. Thus, studies have failed to clearly show that PCE has negative cognitive effects, partly because such effects may be due to concurrent factors. Pregnant mothers who use<unk> , often use other drugs in addition, or they may be malnourished and lacking in medical care. Children in households where<unk>  is abused are at risk of violence and neglect, and those in foster care may experience problems due to unstable family situations. Factors such as poverty that are frequently associated with PCE have a much stronger influence on children's intellectual and academic abilities than does<unk>  to<unk>  in isolation. Thus, researchers have had difficulty in determining which effects result from PCE and which result from other factors in the children's histories.
Prenatal cocaine exposure
Maternal hypothyroidism
Y chromosome microdeletion
Chromosomal fragile site
Child-on-child sexual abuse
Chromosome 2q deletion
Haploinsufficiency of A20
Prenatal testosterone transfer