FDA: What You Should Know About Using Cannabis, Including CBD, When Pregnant or Breastfeeding: https://www.fda.gov/consumers/consumer-updates/what-you-should-know-about-using-cannabis-including-cbd-when-pregnant-or-breastfeeding
The U.S. Surgeon General recently advised consumers that marijuana use during pregnancy may affect fetal brain development, because THC can enter the fetal brain from the mother’s bloodstream. The Surgeon General also advised that marijuana may increase the risk of a newborn with low birth weight. Research also suggests increased risk for premature birth and potentially stillbirth1.
https://mothertobaby.org/fact-sheets/marijuana-pregnancy/pdf/
https://www.medicinenet.com/script/main/art.asp?articlekey=225263
https://www.vogue.com/article/is-cannabis-safe-during-pregnancy-more-expecting-mothers-are-wondering