MONDAY, June 22, 2015 (HealthDay News) -- Doctors should discourage women from using marijuana during pregnancy, due to the potential effects that pot's active ingredients can have on a child's brain development, new guidelines state.
The recommendation was released Monday by the American College of Obstetricians and Gynecologists (ACOG).
"When you look at the evidence, it leads us to use caution in marijuana use during pregnancy," said Dr. Jeffrey Ecker, chair of the AGOG Committee on Obstetric Practice. "For women who are pregnant or thinking about being pregnant, we would encourage them to discontinue using marijuana."
Ecker is also director of obstetrical clinical research and quality assurance at Massachusetts General Hospital in Boston.
Studies show that children exposed to marijuana in the womb have lower scores on tests of visual problem-solving, visual and motor coordination and visual analysis, compared with kids not exposed to pot, the report states.
Prenatal marijuana exposure also has been associated with decreased attention span and behavioral problems.
"We think that it causes some changes in the development of the brain, and can cause long-term behavioral problems in children," said Dr. Katrina Mark, an OB-GYN instructor at the University of Maryland Medical Center in Baltimore.
Marijuana is the most commonly used illicit drug during pregnancy, with roughly half of female marijuana users continuing to use during pregnancy, the ACOG committee said in its new opinion.
Self-reported prevalence of marijuana use during pregnancy ranges from 2 percent to 5 percent, but increases to between 15 percent and 28 percent among young urban women who are struggling economically, the committee said.
Four states -- Colorado, Washington, Oregon and Alaska -- currently have laws legalizing the recreational use of marijuana. Another 19 states allow marijuana use for medical purposes.
Mark regularly sees pregnant women who use marijuana in her practice. Most use pot recreationally, but some say they are using the drug to deal with nausea or other symptoms of pregnancy.
"When we do universal screening, we find alarmingly high numbers," Mark said. "My personal opinion is that the decriminalization and legalization of marijuana is making it more socially acceptable. But even though it's being legalized in some places, that doesn't make it safe for pregnancy."
The ingredient in pot that causes intoxication, tetrahydrocannabinol (THC), has been shown in animal tests to easily cross the placenta and get into the bloodstream of a developing fetus, the ACOG committee report said.
Besides potentially affecting a child's brain development, exposure to marijuana in the womb also might make the child more susceptible to using the drug themselves when they grow up, the report added.
The nervous system of a human fetus can respond to the chemicals in pot within 14 weeks of gestation, and studies have down that 14-year-olds are more likely to be marijuana users if their mothers used pot during pregnancy.
The ACOG committee opinion, which will be published in the July issue of Obstetrics & Gynecology, recommends that doctors counsel women to not use marijuana during pregnancy or breast-feeding, and to share with their patients the potential risks associated with pot.
However, the opinion also emphasized that women who report they are using marijuana while they are pregnant should be treated and counseled, not reported to the authorities for punishment or prosecution.
Both Ecker and Mark acknowledged that the committee made this recommendation based on evidence that is not overwhelming, given that few studies have been conducted on the effects of marijuana during pregnancy.
"For a lot of reasons, there aren't going to be perfect studies here," Ecker said. "It's not a substance that's generally prescribed, or metered and measured in a way that would allow the kind of analyses we would prefer."
Paul Armentano, deputy director of the pro-marijuana group NORML, agreed that the evidence is scant, but added that "cannabis should not necessarily be viewed as a 'harmless' substance'" for pregnant or nursing mothers.
"Ultimately, treating cannabis like other legal, regulated substances means, in certain circumstances, discouraging its use among certain populations," Armentano said. "Society makes such distinctions often, particularly in regard to the consumption of alcohol and tobacco, and no doubt one can argue that such distinctions also ought to be made for cannabis when the available evidence supports doing so."
Women who are using marijuana to deal with morning sickness or other symptoms of pregnancy can be given other drugs that will deal with those symptoms just as effectively, Ecker and Mark said.
"If they're using it for nausea, I offer them alternative treatments that have been studied and proven to be safe," Mark said of her patients. "Marijuana is not the only medication we have available to treat these symptoms."
For more information on marijuana, visit the U.S. National Institutes of Health.