What are safe levels for cannabis use during pregnancy and breastfeeding?

Updated Dec. 3, 2015 at 3:59 p.m.

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Hey, Cannabist! 

Limited available research on maternal marijuana use has prompted many health organizations to discourage moms from using cannabis.

If I smoke just a few hits every few days and I wait a few hours to breastfeed my baby, is that going to harm him? Or if I just smoke once a week and then wait three days to give him milk, will that be harmful? How long should I wait after smoking a few hits to feed my baby? He is almost a year old and I’ll wait until I stop breastfeeding to smoke, but I’m curious as to what your opinion is. Thank you. –Nursing Nuggets

Hey, Nursing Nuggets!
Thanks for writing. I received quite a few breastfeeding and child development questions after answering Mother Mary Jane’s delivery-room drug test question. The discussion of marijuana use by pregnant or nursing mothers brings out heated opinions, to say the least.

Simply put, marijuana use by women who are pregnant or nursing is not recommended.  All cited reports acknowledge a lack of clear, solid data and underscore the health and safety of mother and child as the paramount concern.

The Journal of Perinatology published a 2014 study titled “Cannabis, the pregnant woman and her child: weeding out the myths.”  The notable points made: regular marijuana consumption is a widespread issue in western communities but data is limited regarding use by pregnant women; fetal growth may be affected by use during pregnancy; regular marijuana use significantly increases the risk of adverse effects in neurological development and behavioral problems; and pregnant and breastfeeding marijuana consumers should be advised to decrease or stop use completely. In the study recommendations, it says, “There are no known safe threshold limits for cannabis use in pregnancy.”

In Colorado, the Retail Marijuana Public Health Advisory Committee, a state task force, reviewed scientific literature to make public health recommendations. For pregnancy and breastfeeding, the task force reported most of the findings for effects on exposed offspring were mixed, insufficient and limited, and made specific recommendations for studies to fill “research gaps,” including the length of time THC remains in breast milk. RMPHAC also notes about available research: “Marijuana use was illegal everywhere in the United States prior to 1996. Research funding, when appropriated, was commonly sought to identify adverse effects from marijuana use. This legal fact introduces both funding bias and publication bias into the body of literature related to marijuana use.”

The Colorado Department of Public Health and Environment (CDPHE) released a guide in March, “Marijuana and Your Baby,” which clearly discourages marijuana use. One of the reasons is THC passes through breast milk and stores in the fatty tissues of the baby.

The guide makes the following statement:

Breastfeeding has many health benefits for both the baby and the mother. But THC in marijuana gets into breast milk and may affect your baby. Because THC is stored in body fat, it stays in your body for a long time. A baby’s brain and body are made with a lot of fat. Since your baby’s brain and body may store THC for a long time, you should not use marijuana while you are pregnant or breastfeeding.

CDPHE also states that pumping and dumping breast milk after cannabis use “may not work the same way it does with alcohol” because THC is fat soluble while alcohol is not, and breast milk has significant fat content.

In addition to the patient guide, CDPHE released guidelines for health care professionals on maternal cannabis use. More resources for health care providers are available on this CDPHE webpage.

Other health organizations have positions on the topic too.

This fall, the American Medical Association called for health warnings on cannabis products and in marijuana shops and dispensaries regarding use during pregnancy and breastfeeding.

The American College of Nurse-Midwives, which is celebrating its 60th organizational anniversary this year, has a statement regarding marijuana use. ACNM representative Damaris Hay says, “ACNM utilizes Center for Disease Control (CDC) recommendations and other evidence-based information on the safety of substance-use such as alcohol and marijuana.”

The ACNM Position Statement addresses marijuana use as an addiction problem and encourages a compassionate holistic approach, not a punitive one, to counseling pregnant women about illicit substance use.  Their position says substance use can pose health risks for mother and baby and cites the 2005 National Survey on Drug Use and Health finding that substance use occurs in 18 percent of all pregnancies.

Another national women’s health organization, the American College of Obstetricians and Gynecologists released a Committee Opinion this year discouraging marijuana use by pregnant and nursing women or women trying to conceive.

Although the opinion acknowledges insufficient data and a need for more research, the organization is concerned because certain populations consume marijuana during pregnancy and breastfeeding. The ACOG opinion says: “Although roughly half of female marijuana users continue to use during pregnancy, evidence suggests that the drug may have a negative impact on fetal neurodevelopment.” The opinion continues, “Marijuana is the most commonly used illicit drug during pregnancy. The self-reported prevalence of marijuana use during pregnancy ranges from 2 percent to 5 percent, but increases to 15 percent to 28 percent among young, urban, socioeconomically disadvantaged women.”

Absolutely more research needs to happen to isolate and study marijuana’s health impact on mothers and children. In the meantime, many medical organizations, including nurse-midwives, overwhelmingly say not to expose a prenatal or nursing baby to marijuana.

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