Table 1.

Summary of the main methodological aspects regarding the three most important longitudinal and prospective clinical studies evaluating the effect of perinatal cannabis exposure.

STUDY	POPULATION	GOALS	FOLLOW-UP	REFERENCES
Ottawa Prenatal Prospective Study (OPPS, started in 1978)	698 middle-class, low risk pregnant women Mostly Caucasian and predominantly Canadian cohort of women	Evaluate the effects of prenatal tobacco, alcohol, and marijuana exposure	The offspring was followed until the age of 18–22 years	(68–71)
Maternal Health Practices and Child Development Study (MHPCD, started in 1982)	564 high-risk predominantly single pregnant women with low socioeconomic status Caucasian (43%) and African American (57%) cohort of women	Evaluate the effects of prenatal alcohol and marijuana exposure	The offspring was followed until the age of 14 years	(72–74)
Generation R Study (Gen R, started in 2001)	9778 women living in Rotterdam (The Netherlands) Multi-ethnic cohort of women	Ongoing population-based, large-scaled study aimed to evaluate the effects of prenatal marijuana exposure on the offspring	The offspring will be followed until early childhood	(75–81)