There are many benefits to breastfeeding your baby, and respected organizations like the American Academy of Pediatrics recommend that new mothers breastfeed their children for the first six months. Breast milk contains vitamins and nutrients, as well as illness-fighting compounds. But what if you're a marijuana user? How will your baby be affected if you use weed and also breastfeed?

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"Virtually anything [a mother consumes] goes through breast milk. Most things go into breast milk in small concentrations," Thomas Hale, a professor with the Department of Pediatrics for the Texas Tech University Health Sciences Center and the founder of InfantRisk, said in an interview with ATTN:. Most drugs find their way into breast milk in low concentrations, he added. But if you use high doses of certain drugs, it could negatively affect the child you're breastfeeding. Hale said that he is aware of children who became opiate-dependent because their mothers used high doses of opiates while breastfeeding.

That said, there isn't enough evidence to be sure that using marijuana while breastfeeding will have a significant effect on your baby, Hale said.

"We know that breastfeeding dramatically enhances the IQ and neurobehavioral development in children," Hale said. "Say the mother chooses to use marijuana and breastfeed. Do the two offset each other? Do you gain a few IQ points but maybe not as many?" He said he can't be sure, because he doesn't know how much THC transfers to the breast milk, though he's hoping to study it soon.

Because of the uncertainty, Hale recommended against using marijuana while breastfeeding, just to be safe. "The brain is about half-created during fetal life, and the other half is after birth," Hale said. That means you don't want to risk damaging your baby's brain development while it's still vulnerable.

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But not everyone agrees with that recommendation. Mothers who use marijuana shouldn't be worried about breastfeeding, according to a 2013 article in Obstetrical and Gynecological Survey, which was cited by The Cannabist.

“Because breastfeeding can mitigate some of the effects of smoking and little evidence of serious infant harm has been seen, it appears preferable to encourage mothers who use marijuana to continue breastfeeding while minimizing infant exposure to marijuana smoke and reducing marijuana use,” the article advised.

The research paints a more nuanced picture.

Some studies point to possible damage from using marijuana while breastfeeding, but their results have been hotly debated in the scientific community, Hale said. One 1990 study found babies exposed to THC through breast milk appeared to have decreased motor development by the time they reached the age of one. That said, the study stopped short of concluding that marijuana use during breastfeeding led to impaired development.

"One cannot infer from the results presented here that marijuana exposure during lactation impairs infant motor development," the study concluded. "Marijuana exposure during lactation appeared to be a better predictor of infant motor development, but it does not necessarily mean that the relationship is one of cause and effect."

A 1985 study from the University of Colorado, meanwhile, found no noticeable negative effects to children who had been breastfed by a mother who consumed marijuana.

Some research has shown negative effects in animals from a mother using marijuana while breastfeeding. A 1980 study looked at how baby mice were affected by a mother that was given marijuana compounds during the lactation period. It found that such mice tended to have lower body weights than normal.

Other studies showed that animals had developmental problems when breastfed by a mother that had been given THC. They concluded that protein growth needed for the proper development of the young brain was altered by THC, leading to impaired growth.

Hale cautioned that animal studies do not reflect what would be seen in human studies. It's a "big jump" to assume that what happens to a baby mouse mirrors what would happen to a baby human, he said. He added that the illegal nature of marijuana makes it difficult to study these things. But he said he's hoping to look into it as soon as he can.