Marijuana Exposure During Pregnancy: Is There a Risk?

Research has shown that some babies born to women who abused marijuana during their pregnancies display altered responses to visual stimuli, increased tremulousness, and a high-pitched cry, which may indicate neurological problems in development. During the preschool years, marijuana-exposed children have been observed to perform tasks involving sustained attention and memory more poorly than nonexposed children do. In the school years, these children are more likely to exhibit deficits in problem-solving skills, memory, and the ability to remain attentive.

http://www.drugabuse.gov/infofacts/marijuana.html