If you read the one you've linked, after the dramatic abstract and introduction (to justify their funding), it comes clean and says that the studies are extremely limited but may point to harm. May. Point to.
"The risks of smoking EC during pregnancy are still largely unknown."
"First of all, the risks of smoking EC during pregnancy need to be thoroughly elucidated; in particular, further studies are needed to evaluate the placental vulnerability to EC exposure. Secondly, prenatal effects of the chemical components of e-vapors have not been thoroughly defined in human studies so far. Research gaps also include lack of generalizability and adjustment for confounders like tobacco use, given that most of the subjects enrolled in the aforementioned studies are dual users."
"Little information is available regarding the effect of EC exposure on children's respiratory health. Available data are mainly self-reported and may be subjected to recall bias."
Literally from the link you posted.
So it wasn't hard to find but was apparently hard to read.
Pro-tip for future forays into science literature (which I strongly encourage), when the word "may" appears in an article 37 times, it's not very conclusive.