You can lie down and drink water all you want and lose a pregnancy, or go hang-gliding
and hop
on a pogo stick
and keep a pregnancy; it all depends
on whether the myriad millions of connections that have to be made as the embryo develops, all connect right. If something does not, the embryo will grow until that thing is needed, and then it will fade because that thing is not there. Not the mommy's fault, nothing she did or didn't do.