In a First, Study Examines the Effects of Alcohol, Marijuana, and Meth on Human Placenta

By Kelly Tatera

Photo credit: Jules Pecnard/flickr (CC by SA 2.0)

The results weren’t pretty.

It’s no secret that a mother’s health choices while pregnant have a significant impact on her baby. Recent research has found that drinking during pregnancy increases the risk of alcoholism in the next three generations, and if the mother is obese, the baby is 4 times more likely to be autistic.

Now, researchers have looked into the effects of alcohol, marijuana, and methamphetamine exposure on the human placenta. Animal studies have revealed some of the undesirable effects of prenatal alcohol exposure (PAE) on placental development, but few studies have looked at these effects in our own species. This is the first-ever study to investigate the effects of prenatal exposure to meth, marijuana, and cigarettes on human placental development.

The researchers collected placentas from 103 pregnant women of mixed ancestry at their first clinic visit in Cape Town, South Africa. In the sample, 66 heavy drinkers and 37 non-drinkers were interviewed about their alcohol, cigarette smoking, and drug use at three clinic visits.

Then, a senior pathologist, who was blinded to the different statuses of  the women’s substance exposure, performed comprehensive examinations on each placenta sample using a standardized protocol.

The results, which are published in the National Center for Biotechnology Information, revealed that alcohol, marijuana, and methamphetamine were associated with distinct patterns of “pathology,” a term to describe the changes that result from a disease.

Alcohol exposure was linked to decreased placental weight and a smaller placenta-to-birth weight ratio, while methamphetamine and marijuana were associated with larger placental weight.

Additionally, alcohol exposure was linked to a higher risk of placental hemorrhage, which is when bleeding between the uterine wall and placental membrane occurs.

The researchers also found that alcohol use and cigarette smoking were associated with a lower risk of intrauterine passing of meconium, which is a dark green fecal material that is produced in the intestines of a fetus before birth (yep, sounds pleasant).

In a healthy baby, the meconium will be stored in the intestines until after birth, but if it passes through to their lungs during or before delivery, there can be serious health problems, including acute fetal stress and/or hypoxia (oxygen deficiency). While there was a decreased risk linked with alcohol, there was an increased risk associated with methamphetamine.

Teratogens are any drugs or agents that could have a toxic effect on an embryo or fetus and cause birth defects, and the researchers hope that these study findings highlight the importance of long-term teratogenic effects of prenatal alcohol and drug exposure.