Can marijuana cause neurological development problems in infants?

The test will be positive if THC (tetrahydrocannabinol) (one of the psychoactive constituents of marijuana) is detected in a blood or urine sample. Bear in mind that the body stores THC in lipids (fat) from which it is released into blood or urine over a period of weeks and even months.
So, a newborn can test positive for marijuana if his or her mother has ingested enough of it (more than a few joints) in the month or two preceding giving birth.