One of the 30 + articles in CBI RL files has a very neat title -- "It's Not Your Mother's Marijuana: Effects on Maternal-Fetal Health and the Developing Child".  It states that marijuana today is much more potent that Mj in the 80's and 90's !
Research shows developmental delays if used in pregnancy and Mj is present in mother's milk.

However, 2017 ACOG statement says:there are insufficient data to evaluate the effects of mj use on infants during lactation and breastfeeding, and in the absense of such data, mj use is discouraged".
A 1990 article states that mj exposure via mother's milk during the first month postpartum appeared to be associated with a decrease in motor development at one year.  
Maternal Marijuana Use During Lactation and Infant Development at One Year. Astley & Little, 1990,  Neurotoxicology and Teratology, 12, pp.161-168.
Transfer of Inhaled Cannabis Into Human Breast Milk, Baker et al. 2018, Obstet Gynecol 131 (5),  783-788.  Says "mothers should be cautious using cannabis during pregnacy and breastfeeding."
A survey of Lactation Professionals shows that we vary widely in recommendations about mj use.  {But we also vary widely on other topics too, LOL}Bergeria & Heil.  Surveying Lactation Professionals Regarding Marijuana Use and Breastfeed  2015 Breastfeeding Medicine 10 (7) 377-380.
THC was measurable in a majority of breast milk samples up to ~6 days after maternal mj use.  Study was dnme between 2014 & 2017.Bertrand et all, 2018 Pediatrics142 (3), 

Crume et all. Cannabis 2018. Use during the perinatal period in a state with legalized recreational and medical  marijuana: The association between Maternal characteristics, breastfeeding patterns, and neonatal outcomes,  J of Peds.  Their findings underscore the importance of screening for mj use during screening at prenatal care, counseling about the adverse health consequences of continued use during pg and lactation.
Colorado Dept of Public Health & Environment has a number of handouts for mothers and counselors.
In 1987 Mothering Magazine said Beware.
and so on...I tried to cite the more recent articles, but they go on and on.  Pat in SNJ

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