National Institute on Drug Abuse
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What about pregnancy: Will smoking marijuana hurt the baby?
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Doctors advise pregnant women not to use any drugs because they might harm the growing fetus. One animal study has linked marijuana use to loss of the fetus very early in pregnancy.
Some scientific studies have found that babies born to marijuana users were shorter, weighed less, and had smaller head sizes than those born to mothers who did not use the drug. Smaller babies are more likely to develop health problems. Other scientists have found effects of marijuana that resemble the features of fetal alcohol syndrome. There are also research findings that show nervous system problems in children of mothers who smoked marijuana.
Researchers are not certain whether a newborn baby's health problems, if they are caused by marijuana, will continue as the child grows. Preliminary research shows that children born to mothers who used marijuana regularly during pregnancy may have trouble concentrating.
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| What happens if a nursing mother uses marijuana? |
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When a nursing mother uses marijuana, some of the THC is passed to the baby in her breast milk. This is a matter for concern, since the THC in the mother's milk is much more concentrated than that in the mother's blood. One study has shown that the use of marijuana by a mother during the first month of breastfeeding can impair the infant's motor development (control of muscle movement).
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| How does marijuana affect the brain? |
THC affects the nerve cells in the part of the brain where memories are formed. This makes it hard for the user to recall recent events (such as what happened a few minutes ago). It is hard to learn while high - a working short-term memory is required for learning and performing tasks that call for more than one or two steps.
Among a group of long-time heavy marijuana users in Costa Rica, researchers found that the people had great trouble when asked to recall a short list of words (a standard test of memory). People in that study group also found it very hard to focus their attention on the tests given to them.
Smoking marijuana causes some changes in the brain that are like those caused by cocaine, heroin, and alcohol. Some researchers believe that these changes may put a person more at risk of becoming addicted to other drugs, such as cocaine or heroin.
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It may be that marijuana kills brain cells. In laboratory research, scientists found that high doses of THC given to young rats caused a loss of brain cells such as that seen with aging. At 11 or 12 months of age (about half their normal life span), the rats' brains looked like those of animals in old age. It is not known whether a similar effect occurs in humans.
Researchers are still learning about the many ways that marijuana could affect the brain. |
