Prenatal nicotine, cannabis exposures not a hazard to neurodevelopmental outcomes

Neither prenatal nicotine nor cannabis exposure adversely affects offspring intelligence quotient (IQ), a study reports. However, cannabis exposure appears to have unfavourable effects on attention in early childhood.

Researchers conducted a secondary analysis of two parallel multicentre randomized controlled trials of treatment for hypothyroxinaemia or subclinical hypothyroidism among pregnant individuals enrolled at 8–20 weeks of gestation.

The study population included 1,197 maternal–child dyads. All mothers provided a urine sample at baseline to screen for the presence of nicotine (ie, cotinine), cannabis (ie, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol [THC-COOH]), or both metabolites.

Child IQ at 60 months was the primary outcome. Cognitive, motor and language, attention, behavioural and social competency, and differential skills were also assessed at 12, 24, 36, and 48 months as secondary outcomes.

Results showed that out of 1,197 pregnant individuals, 99 (8.3 percent) had positive cotinine samples, 47 (3.9 percent) had positive THC-COOH samples, and 33 (2.8 percent) had samples positive for both cotinine and THC-COOH. These three groups varied in terms of self-reported race and ethnicity, education, marital status, insurance, and thyroid status.

Median IQ was comparable between cotinine-exposed and -unexposed children (90 vs 95; adjusted median difference, −2.47, 95 percent confidence interval [CI], −6.22 to 1.29) and THC-COOH-exposed and -unexposed children (89 vs 95; adjusted median difference, −1.35, 95 percent CI, −7.76 to 5.05).

On further analysis, children with THC-COOH exposure compared with those who were unexposed had poorer attention scores at 48 months of age (57 vs 49; adjusted median difference, 6.0, 95 percent CI, 1.11–10.89).

More studies that examine associations between child neurodevelopmental outcomes and prenatal nicotine and cannabis exposure, with a focus on timing and quantity of exposure, are required.