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Ronnie Falcao, LM MS, a homebirth midwife in Mountain View, CA

Student report on marijuana use during pregnancy or labor and birth

I am attending a 4 day forensics seminar this week. Today the topic was forensic toxicology. The presenter just happened to have done his research project on the effects of marijuana on humans. After the lecture I had the opportunity to ask him what he knew about its effects on pregnancy and the neonate. He said while he could not personally say what the labor experience would be like for the woman who decides to self medicate with marijuana since he had never been pregnant :-), he had, however, smoked marijuana could understand why some might consider it to be helpful. For a scientist, he wasn't an uptight kind of guy! This is what I learned.

THC persists in the adult brain for about 48 hours. This is in an adult with a fully functioning liver who can better metabolize drugs than an infant with its immature liver can, so it is to be expected that the drug would persist for longer in the newborn. THC readily crosses the placenta. THC concentrates in fatty tissue and the brain is made up of a large portion of lipids so THC is sequestered there, as found in adult studies. While studies haven't been done on infants, a higher concentration is expected to be found in infant brains than in adult brains (think of fentanyl and other opioids), particularly since infants have much lower body fat than adults so the only place for THC to go, essentially, is the brain.

Expected effects on the newborn are respiratory depression, sleepiness and feeding problems. Anecdotal stories of "I've had moms who regularly used it and I never saw problems" are not sufficient proof of safety, in part because you can't tell what a particular infant's status would have been like without ingestion of the drug. Maybe the one who had no nursing problems would have been a voracious nurser, for example. Studies on animals have shown decreased birth weights and slow growth but no major malformations. Again, saying you have moms who used but had babies over 8 lbs doesn't mean anything, maybe the baby would have been 9 lbs without the drug - you don't know. The studies look at larger numbers while controlling for the factor of drug use and look at averages. If all other factors match up, the average weights should be similar.

He said, while he would not anticipate any long term problems in babies due to THC and thinks it would clear without much difficulty after several days, but those first few days of life are the most difficult for that baby and making its respiratory adjustment and initiation of breastfeeding more difficult is not the ideal situation. He said this is the same reason doctors are so cavalier about fentanyl as the drug of choice despite its known effects of the neonate. Kind of an, "Oh, well, it will all be OK in a few days and there is no long term harm."

He said THC is found in the urine of occasional users for about 5 days afterward and up to 21 days later in chronic regular users (although it is theoretically possible to find it up to 30 days but he has never seen it past 21). The suggestion would be for those who want to continue marijuana use in pregnancy but not give birth to a drugged baby, especially when they are working hard to protect their babies from the effects of all those legal drugs, is to lay off the pot before term by the times mentioned above to make sure the drug is cleared from the mom's system.