Nat Med: Marijuana use during pregnancy increases the risk of autistic children.

Surveys show an increase in cannabis use during pregnancy, with many women continuing to use cannabis throughout their pregnancy.
with the legalization of recreational marijuana in many jurisdictions in the United States and Canada, there are concerns about the potential adverse effects of prenatal exposure to marijuana on fetuses.
previous studies have shown that cannabinol, including tethydrocannabinol, can easily pass through the placenta and into the blood of the fetus.
exposure to cannabinin in the womb can disrupt the fetus' endologic cannabinin signaling system, which has several roles in embryonic development.
and animal studies have shown that disrupting endologic cannabinin signaling can lead to defects in neuron circuits and affect fetal neurodevelopment.
, researchers recently published a retrospective analysis of all live births in Ontario, Canada, between April 1, 2007 and March 31, 2012, using provincial birth registration information that contained information about marijuana use during pregnancy.
researchers linked pregnancy and birth data to the provincial health administration database to determine neurodevelopmental outcomes in children.
researchers used matching techniques to control confuse factors and used Cox-scale risk regression models to examine the association between prenatal marijuana use and neurodevelopment in children.
between 1 April 2007 and 31 March 2012, a total of 689,071 newborns were registered in BORN in Ontario.
excluded some cases, the final group was based on 508,025 newborns.
primary analysis of autism spectrum disorder (ASD) and secondary analysis of neurodevelopmental outcomes excluded children who had lost their Ontario health insurance eligibility or died before 18 months (n-4,960) or 4 years of age (n-10,204), resulting in a final analysis of 503,065 and 497,821 people, respectively.
the average age of the mothers of these children was 30.1 years (s.d. , 5.6), the average gerensity at the time of delivery was 38.9 weeks (s.d. , 1.7), and 51.4 per cent of the children were male.
reported 0.6 per cent use of cannabis during pregnancy.
analysis comparing excluded records with the analysis group shows that there are some moderate differences in maternal age, regional income, status, maternal health status, rural residence and drug use during pregnancy.
found a link between marijuana use by pregnant mothers and the rate of autism spectrum disorder in offspring.
In children exposed to cannabis, the rate of diagnosis of autism spectrum disorder was 4.00/1000 years, compared with 2.42 years for unexposed children, and the fully adjusted risk ratio in the matching queue was 1.51 (95 percent confidence interval: 1.17-1.96).
of mothers who use cannabis during pregnancy have a higher rate of intellectual and learning disabilities, although statistically unreliable.
, the researchers note that these results should be interpreted with caution, given the potential for residual conferring factors.
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