Smoking both marijuana and tobacco during pregnancy may cause greater health risks than tobacco or pot use alone, according to a recent study from Baylor College of Medicine in Houston.
While researchers found marijuana use did not cause significant health problems around the time of birth, co-use of marijuana and tobacco increased the risk of several negative health outcomes for the mother and baby.
The study confirmed tobacco and pot use during pregnancy may increase the risk for:
“Tobacco use is clearly detrimental to fetal health, and therefore baby health,” said Dr. Carri Warshak, an associate professor at the University of Cincinnati who studies how marijuana use affects pregnancy. “It is very likely that marijuana use shares some of the untoward effects.”
Although the study results showed no significant health differences between women who used marijuana and those who did not, the researchers expressed concern about the prevalence of concurrent cigarette and marijuana use during pregnancy and the negative effects.
“To optimize fetal health and the health of the child, it is best to avoid use of marijuana and tobacco in pregnancy,” Warshak said.
To learn more about how marijuana and tobacco use affects the health of mothers and babies, the study followed the outcomes of 12,069 pregnancies from January 2011 to June 2015. Researchers surveyed participants around the time of birth about their use of pot, tobacco and other nicotine-containing products during pregnancy.
While less than 1 percent of participants reported marijuana use during pregnancy, 45 percent of that group smoked pot and cigarettes concurrently.
Study results showed women who smoked marijuana and tobacco while pregnant were 2.5 times more likely to deliver prematurely and about three times as likely to have babies with decreased head size or low birth weight. They were also more than twice as likely to experience asthma and 2.5 times as likely to experience pregnancy-related high blood pressure.
Women who used only tobacco, only marijuana or both were four to seven times more likely to have depression or anxiety than women who used neither.
Study participants who smoked cigarettes alone during pregnancy were more likely to have babies with smaller head size, lower birth weight and premature delivery. However, these risks were significantly higher when marijuana and cigarettes were used together.
Many past studies have examined the effects of prenatal marijuana exposure on children, and some have identified links to emotional and behavioral issues later in life.
A 2015 study published in the American Journal of Obstetrics and Gynecology sought to determine the prevalence of marijuana use in pregnant and nonpregnant women of reproductive age. Out of more than 90,000 participants between the ages of 18 and 44, 3.9 percent of pregnant women and 7.6 percent of nonpregnant women reported using marijuana in the past month.
Multiple studies cited in a 2011 review article about prenatal exposure to tobacco, marijuana and various other drugs have identified the potential for future developmental problems and vulnerability to substance abuse.
One such study found that 10-year-olds exposed to marijuana in the womb showed more symptoms of depression than those who weren’t exposed. In addition, study participants between the ages of 16 and 21 who experienced prenatal marijuana exposure were twice as likely to use tobacco and marijuana, and they were 1.3 times as likely to be high-frequency marijuana users.
The U.S. National Library of Medicine has cited several studies linking prenatal marijuana use to deficiencies in school achievement, such as reading and writing. The studies showed exposure to marijuana in the womb also had negative effects on problem solving skills, memory, planning, impulsivity and attention span.