If you can get her trained before you give birth that is great, as they don't recommend training during the time of a new baby's arrival. We were going to train Kameron in the 4wks Andrew had off after Lachlans birth and alot of places said don't do it while there is a new baby, as the child will feel like you are forcing them to get rid of nappies. If you are pregnant now (fingers crossed) 18mths is probably a bit too soon imo.

Love