A possible folkloric connection

In West African folklore and that of Iran, Armenia, the Caucasus, and Central Asia there are stories about evil forces that cause miscarriages and replace one's child with their own evil offspring. These changeling/imp forces are called "Al" or "Abiku" (see Ben Okri's THE FAMISHED ROAD). Water plays a role, but in the case of the Al, it is a force of escape for the evil spirit, sealing the mortal's fate; whereas in other traditions, evil spirits can't cross water. These traditions might offer more tools to try to grasp this film's very thin plot. I think the acting in this was great, as was everything else except for the writing regarding the child. I wanted to have a few more clues on to how it functioned and a sense of whether or not Louise had sought this actively in any way. We've all seen Rosemary's Baby, the Ring, etc. before and the ending and movie logic here was far too vague to be completely satisfying. I also wondered why Elena didn't do more to try to research what might be happening to her--especially if she felt it was malevolent.