New research suggests that marijuana can linger in breast milk for almost a week, raising concerns about mothers using pot during and after pregnancy.

While further research is still needed to determine what impact marijuana use could have on babies, the American Academy of Pediatrics (AAP) has issued a response to the new report recommending that pregnant and nursing mothers avoid the drug altogether.

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In the study, researchers tested breast milk samples from 50 women who used marijuana either daily, weekly or occasionally, and detected THC – the active component of the drug – in 63 percent of the samples for up to six days after the mother's last reported use.

The research was published online Aug. 27 in the journal Pediatrics, a publication of the AAP. Meanwhile, a second troubling report in the same issue of the journal suggested that many pregnant women mistakenly believe that marijuana is harmless.

Prenatal marijuana use is on the rise in the U.S., according to the AAP report. One government study found that about 2.4 percent of pregnant women had smoked pot in the past month in 2002; by 2014, that had increased to almost 4 percent.

At the same time, marijuana is being "touted" on social media as a good remedy for morning sickness, the AAP report authors noted. And as a growing number of U.S. states legalize marijuana, some women may be left with the impression that the drug is safe to use during pregnancy.

More research is needed to determine the long-term effects marijuana in breast milk has on children, but the study’s authors suggest it is “reasonable to speculate” that exposure to THC “could influence normal brain development” in infants and children.

More information

The Academy of Nutrition and Dietetics offers advice on what to eat and drink while breastfeeding.

This content originally appeared on HealthLibrary.