Maternal cannabis use and birth weight: a meta-analysis

Area of Science:

• Reproductive Health
• Perinatal Epidemiology
• Drug Effects on Fetal Development

Background:

• Maternal substance use during pregnancy is a significant public health concern.
• Cannabis use among pregnant women has increased, necessitating an understanding of its impact on fetal development.
• Existing research on cannabis and birth weight has yielded inconsistent results, often confounded by concurrent cigarette smoking.

Purpose of the Study:

• To quantitatively assess the association between maternal cannabis consumption and infant birth weight.
• To differentiate the effects of various frequencies of cannabis use on mean birth weight.
• To determine the odds of low birth weight associated with prenatal cannabis exposure.

Main Methods:

• A meta-analysis was conducted on 10 published observational studies, with data adjusted for cigarette smoking.
• Studies were categorized for analysis based on low birth weight outcomes and mean birth weight differences.
• Data from 32,483 pregnancies were analyzed using fixed and random effects models.

Main Results:

• Any cannabis use during pregnancy was not significantly associated with an increased odds of low birth weight (pooled OR 1.09, 95% CI 0.94-1.27).
• Infrequent cannabis use (≤ weekly) showed a non-significant increase in mean birth weight (62 g).
• Frequent cannabis use (≥ 4 times/week) was associated with a significant reduction in mean birth weight (131 g), though heterogeneity was noted.

Conclusions:

• Current evidence suggests that typical amounts of cannabis consumed by pregnant women are not associated with low birth weight.
• More research is needed to fully understand the nuanced effects of different cannabis consumption patterns on fetal growth.
• The findings indicate a need for cautious interpretation of cannabis's impact, particularly regarding frequency and dosage during gestation.