Once the Sim is pregnant, the pregnancy will proceed as normal. If you don't have it in your active household (meaning you can't click on the ghost to see it's needs and whatnot) then you can only interact with it between about 11:30 PM to 5:00 AM Sim time. Having the ghost as part of the household makes this process much easier because they are available to interact with them at all times of the day. Have a Sim throw a Ghost Potion during pregnancy.Build the relationship between the ghost and playable Sim until you have the option to pick up the grave and move it to your Sim's home lot.Go to the graveyard at night and invite the ghost Sim to the playable Sim's house.Kill off a Sim and make a playable ghost by accepting the 'Oh My Ghost!' opportunity after the Sim has died.Marry the ghost to add it to the household.Steal their grave (if the Sim has the Kleptomaniac trait) and put it on their current home lot.The trick is to get the ghost to come home with the Sim, first. A Female Sim must interact with a ghost every night when it appears near its urn or tombstone and build a relationship to at least 'romantic interest', then when at home, try for a baby. However, a ghost baby requires some methods that a regular baby does not. There are many ways for obtaining a ghost baby.
