Comprehensive Review of 89 Studies Concludes Cannabis Should Be Avoided During Pregnancy | Research

The takeaway

An overview of 89 studies and reviews found potentially harmful effects of prenatal cannabis exposure on fetal growth, some neonatal outcomes, and some later-life outcomes.

Prenatal care providers, pregnant women considering cannabis, public health communicators

89 studies reviewed: prenatal cannabis harmful for all fetal growth measures

What the researchers found

Across 89 included studies/reviews, prenatal cannabis exposure showed potentially harmful impacts on all fetal growth measures, some neonatal outcomes, some later-life developmental outcomes, and some maternal outcomes. Evidence for other outcomes was mixed. The authors concluded cannabis should be avoided during pregnancy.

Why it matters

As prenatal cannabis use rises, this is the most comprehensive evidence synthesis to date. Its clear conclusion, to avoid cannabis during pregnancy, provides the strongest evidence basis yet for clinical guidance.

The numbers in context

89 studies/reviews included. Harmful effects found for: all fetal growth outcomes, some neonatal conditions, some later-life outcomes, some maternal outcomes. Mixed evidence for remaining outcomes.

How the study worked

Umbrella review combining an overview of systematic reviews, evidence gap mapping, targeted review updates, and de novo synthesis, searching PubMed, MEDLINE, Embase, and CINAHL with duplicate risk of bias assessment.

What this study cannot tell us

Cannot fully separate cannabis effects from confounders like tobacco, other substance use, and socioeconomic factors. Cannabis product types and doses vary widely. Publication bias possible. Some outcome areas had limited data.

How to read the evidence

Highest-level evidence synthesis (overview of reviews) with rigorous methodology provides strong conclusions.

When this study was published

2025 umbrella review representing the most comprehensive pregnancy-cannabis evidence synthesis available.

The bigger picture

This review settles the debate at the evidence level: the overall weight of research supports avoiding cannabis during pregnancy. The challenge now is translating this evidence into effective public health messaging.

Questions still open

Which specific cannabinoids drive the harmful effects? Is there a safe amount during pregnancy? How can public health messaging reach pregnant cannabis users effectively?

Common questions

Is it safe to use cannabis during pregnancy?

This comprehensive review of 89 studies concluded cannabis should be avoided during pregnancy. Prenatal exposure was associated with potentially harmful effects on fetal growth, some neonatal conditions, some developmental outcomes, and some maternal outcomes.

What specific harms are linked to prenatal cannabis exposure?

All fetal growth measures (birth weight, length, head circumference) showed harmful effects. Some neonatal conditions, later-life developmental outcomes, and maternal outcomes were also affected, though evidence was mixed for other specific outcomes.

Read the original research

The impact of using cannabis during pregnancy on the infant and mother: An overview of systematic reviews, evidence map, targeted updates, and de novo synthesis.

The Australian & New Zealand journal of obstetrics & gynaecology, 65(3), 312-328

View on PubMed ↗Publisher’s paper ↗

Citation

Munn, Zachary; Pollock, Danielle; Stone, Jennifer; Hasanoff, Sabira; Gordon, Andrea; Price, Carrie; Stark, Michael; Barker, Timothy Hugh. (2025). The impact of using cannabis during pregnancy on the infant and mother: An overview of systematic reviews, evidence map, targeted updates, and de novo synthesis.. The Australian & New Zealand journal of obstetrics & gynaecology, 65(3), 312-328. https://doi.org/10.1111/ajo.13916