Marijuana is the most commonly used recreational drug during pregnancy, and doctors predict that the ongoing legalization of the drug will make it even more popular. In the near future, the experience of seeing a pregnant woman vape might become akin to seeing one sip on a glass of Cabernet; there’d be a frisson of concern offset by the fact that lots of other women have smoked a little weed during pregnancy and their children seem fine.

As with alcohol, the American Congress of Obstetricians and Gynecologists recommends abstaining from marijuana during pregnancy. And as with alcohol, the research is less conclusive than such recommendations let on. This doesn’t mean nauseous, nervous pregnant women should rush to add items from their local pot dispensary to their baby registry—only a reminder that when it comes to fetuses and weed, there is still a lot we don’t know.

The latest study to complicate our understanding on the subject comes from Shayna Conner, an assistant professor in the division of maternal fetal medicine and ultrasound at Washington University in St. Louis School of Medicine. She and her team reviewed and analyzed 31 previously published studies on marijuana use during pregnancy and found that, once they controlled for tobacco, there was no correlation between a mother’s pot use and adverse neonatal outcomes, including low birth weight and preterm delivery.

The authors conclude that while such findings don’t greenlight marijuana use during pregnancy, they should encourage doctors and public health officials to shift some of their focus away from marijuana and put their energy into discouraging more harmful substances like alcohol and tobacco.

Though as Tara Haelle points out at Forbes, even this modest recommendation might be imprudent. She explains that a number of the papers that Conner’s meta-study relied on were not thorough enough to account for the various possible effects that marijuana use during pregnancy could cause. Also, the recent study is limited to neonatal outcomes; it does not take into account pot-related behavioral problems that might develop later on. A different study published last year found that while studies on marijuana use are generally flawed because of researcher’s inability to separate other variables, including tobacco use and sociodemographic factors, there is “an emerging body of evidence indicating that marijuana may cause problems with neurological development, resulting in hyperactivity, poor cognitive function, and changes in dopaminergic receptors.”

As I’ve written before, there is a dearth of clinical research on pregnant women and drugs, legal and not. We know very little about how to treat the ailments of pregnant women, ailments which don’t, unfortunately, magically disappear upon conception. And then there’s the fact that many women feel the worst they have ever felt during pregnancy and could greatly benefit from some relief. This latest study isn’t cause to incorporate marijuana into one’s prenatal wellness routine, but it’s evidence that the drug, which is increasingly being viewed at as a form of medicine, should be further studied in the context of pregnant women.