Children exposed to maternal cannabis during pregnancy had higher BMI and altered body fat distribution at age 10, but similar patterns for paternal cannabis use suggest shared family lifestyle factors rather than direct fetal programming.
Obstetricians, pediatricians, parents, and researchers studying long-term effects of prenatal exposures.
Similar effects for maternal and paternal use suggest family factors, not fetal programming
What the researchers found
Children exposed to maternal cannabis during pregnancy had higher BMI (0.26 SDS), android/gynoid fat ratio (0.21 SDS), and fat-free mass index (0.24 SDS) at age 10. However, paternal substance use showed similar associations with child cardiometabolic outcomes, suggesting shared family-based social and lifestyle factors rather than direct intrauterine effects.
Why it matters
By comparing maternal and paternal exposure associations, this study provides an important reality check: what looks like a direct effect of prenatal cannabis exposure may actually reflect the environment children grow up in.
The numbers in context
4,792 families. Maternal cannabis exposure: +0.26 SDS BMI, +0.21 SDS android/gynoid fat ratio, +0.24 SDS fat-free mass index. Paternal associations were similar in magnitude.
How the study worked
Population-based prospective cohort of 4,792 mothers, fathers, and children. Parental substance use assessed by questionnaires during pregnancy. Child outcomes measured at age 10: BMI, body fat (DXA), blood pressure, lipids, glucose, and insulin.
What this study cannot tell us
Self-reported substance use. Paternal data used as negative control but may have direct biological effects (epigenetic). Cannot fully rule out direct fetal effects of cannabis. Loss to follow-up over 10 years.
How to read the evidence
Large prospective cohort with objective childhood measurements, strengthened by paternal exposure comparison.
When this study was published
Published in 2022 with outcome measurements at age 10.
The bigger picture
This study illustrates a critical methodological point in prenatal exposure research: when paternal exposures (which cannot directly affect the fetus) produce similar associations as maternal exposures, confounding by shared family factors is the most likely explanation.
Questions still open
- Are the observed differences clinically meaningful? Could epigenetic paternal effects also contribute? Would controlling for diet, exercise, and socioeconomic factors fully explain the associations?
Common questions
Does cannabis during pregnancy cause childhood obesity?
Why does paternal cannabis use matter for this research?
Read the original research
Foetal tobacco and cannabis exposure, body fat and cardio-metabolic health in childhood.
Pediatric obesity, 17(3), e12863
Citation
Cajachagua-Torres, Kim N; El Marroun, Hanan; Reiss, Irwin K M; Santos, Susana; Jaddoe, Vincent W V. (2022). Foetal tobacco and cannabis exposure, body fat and cardio-metabolic health in childhood.. Pediatric obesity, 17(3), e12863. https://doi.org/10.1111/ijpo.12863
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