Sure this isn't a translation from English and someone messed it up?
One of the drugs where the leaflet contains this sentence is betamethasone:
https://www.msd.de/fileadmin/files/gebrauchsinformationen/GI...If you look for it on UK websites, you get "Always inform your doctor if you are pregnant or
planning a pregnancy, before using any medicine."
https://www.netdoctor.co.uk/medicines/a6306/betamethasone-so...You can search for "pregnant or planning a pregnancy" on UK websites and you'll find a lot more Ghits.
Even on US websites, you'll get: "Tell your doctor if you are pregnant or plan to become pregnant while using this medicine."
https://www.mottchildren.org/health-library/d03561a1As a GNS, I agree that the German sentence is flawed and, as said somewhere else, I am not fond of guesswork based on context. Guessing the right word may work, but it is quite risky most of the time.
Else, they could have just said "bei Schwangerschaft." Phil's version is pretty rare, it seems.
Best