As a point of note, this won’t result in a ghost baby, but due to the miracle of childbirth will instead give you an actual newborn to take care of.
With ghosts being able to have relationships and get married, it seems the logical next step was to have those same ghosts get pregnant. Modder PolarBearSims is the mind behind the Ghost Can Have Babies! mod, so direct any and all disapproving glances at them. Depending on your grip on the delicate nature of gaming realism, you might be curious to see ghosts having babies.