Table 2.

Summary of findings of 3 important longitudinal prospective studies

Gestational age and birth weight
  • Delivery at earlier gestational age in exposure group

  • No differences in birth weight

  • Shorter gestation for exposure after first trimester only

  • Increased birth weight after third trimester exposure

  • Fetal growth reduced from second trimester onward

  • Lower birth weight in exposed group

  • Increased startle response

  • No differences in neonatal behaviour

  • Not examined

  • 6 mo to 3 y: no neurobehavioural defects

  • Not examined

  • 18 mo: increased aggression and inattention problems in exposed girls only

  • 4 y: poorer performance on verbal and memory subscales

  • No effect on global intelligence

  • 3 y: lower short-term memory and verbal reasoning scores

  • 3 y: no significant deficits in cannabis-exposed group

School age
  • 6 y: poorer sustained attention. No effect on impulse control

  • Higher parental ratings of inattention and misconduct

  • 6 to 9 y: impaired visual perception, visual memory, and language comprehension

  • Increased distractibility

  • 6 y: more impulsivity, hyperactivity, and delinquency

  • 9 y: impaired abstract and visual reasoning

  • Impaired executive functioning

  • Poorer reading, spelling, and academic achievement

  • Depressive and anxious symptoms

  • 6 to 8 y: altered brain morphology in the frontal cortex

Teens and young adults
  • 14 to 16 y: deficits in visual-cognitive functioning

  • 17 to 22 y: deficits in executive functioning, response inhibition, and visual-spatial working memory

  • Increased smoking and early substance use

  • 14 to 16 y: deficits in academic achievement (especially reading), information processing speed, and visual motor coordination

  • Increased rates of delinquency

  • 17 to 22 y: increased rates of smoking and early initiation of substance use

  • Not yet examined

  • MHPCD—Maternal Health Practices and Child Development, OPPS—Ottawa Prenatal Prospective Study.