A new mother in Oregon says she wants to breast-feed her baby even though she regularly smokes marijuana, but experts say they would be concerned about the risks of the drug to the baby's brain.

The mother, Crystal Cain, said she is a medical-marijuana user who smoked the drug during her pregnancy to reduce anxiety and nausea, according to the Portland TV station KATU. Her baby was born 8 weeks premature, and Cain planned on breast-feeding the child because of the known benefits of breast-feeding.

But doctors at the hospital did not allow Cain to breast-feed until she signed a waiver acknowledging the potential risks of using marijuana while breast-feeding, KATU said.

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"There's not enough information [on the risks] because nobody tests it," Cain was quoted as saying. [Trippy Tales: The History of 8 Hallucinogens]

t's true that few studies have looked at the risks of smoking marijuana while breast-feeding, and many of the studies that have examined this question were conducted several decades ago. However, several organizations, including the American Academy of Pediatrics, discourage the use of marijuana by breast-feeding mothers, in part because of concern that the drug may affect the baby's brain development.

What is clear is that the drug can get into breast milk, and into the baby's body.

The active ingredient in marijuana, THC, is fat soluble and can be stored in the fat tissue for quite a while. "Any drug that is fat soluble gets into fat (tissue), and breast milk has lots of fat because that's what's good for the baby," said Dr. David Mendez, a neonatologist at Miami Children's Hospital, who had not treated Cain or her baby. The more marijuana that a woman smokes, the greater the amount of THC in her breast milk, Mendez said.

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Babies who have been breast-fed by a woman who smokes marijuana can have a positive urine test for marijuana for up to three weeks, said Martha Lasley, a lactation consultant from Winnie Palmer Hospital for Women & Babies in Orlando. However, the amount of THC that's transferred to the baby through breast-feeding is not enough to produce a high, Lasley said.

There is also some concern that smoking marijuana can lower women's levels of prolactin, the hormone needed for breast-milk production, Lasley said.

A 1990 study found that a baby's exposure to THC in the first month of life was linked with reduced movement and coordination skills at age 1. Doctors have also observed lethargy, less frequent feeding and shorter feeding times in babies exposed to THC, according to a 2005 review in the journal Canadian Family Physician.

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However, another study conducted in the 1980s found no differences in weaning, growth or mental development between children exposed to marijuana during breast-feeding, and those not exposed, according to a 2009 review. No studies have examined the possible long-term effects of marijuana exposure during breast-feeding. The 2009 review said that there is concern that THC could alter brain cell metabolism as the baby's brain grows in the first month of life.

Mendez agreed, saying that the risk might be particularly concerning for a premature baby.

"For babies born premature, we know they're under more severe neurological stress," Mendez said. "I can't imagine how marijuana would help that at all," Mendez said. "Why would you want to take any risk?"

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Mendez added that a drug that alters mood and perception, as marijuana can, may also affect people's ability to care for their children. "This is at a time when your baby is completely dependent on you," he said.

Smoking in general is also discouraged for new parents because it is linked with an increased risk of conditions such as asthma and sudden infant death syndrome (SIDS), the AAP says.

Still, breast-feeding has many known benefits, including a reduced risk of SIDS, leading some sources to advocate taking a more nuanced approach to marijuana use during breast-feeding, as opposed to a complete ban. LactMed, a database from the National Institutes of Health that has information on drug and chemicals during breastfeeding, says that "marijuana use should be minimized or avoided by nursing mothers." But the database also notes that there is little evidence of serious harm, so "it appears preferable to encourage mothers who use marijuana to continue breastfeeding while minimizing infant exposure to marijuana smoke and reducing marijuana use."

A 2012 review on the topic concludes by saying: "There are no studies that support breastfeeding and use of marijuana. However, with conflicting results [of studies], further studies and case-by-case considerations are warranted in cases of occasional use."

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Some studies have linked marijuana use in pregnancy to an increased risk of having a low-birth weight, small for gestational age, or premature baby. Some studies also suggest a link between marijuana use during pregnancy and the child having attention and learning problems later in life.

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