This is not the case in my game, was that reverted later? (Or is it maybe VIET+?)
No changes were made to religions at all in VIET(+) as far as I know, and Germanic isn't even a religion in HIP.
Has to be something other than this
Edit:
It's just a modifier which is added by event, looking for a character that is both at war and in command. Lowers fertility.
Hmm... quite simple, actually.
But I guess that's just what a genius does, to find out or do simple things, which
afterwards everyone deems quite obviouse
Edit2: Just wanted to say how awesome the "female flavour" features can be...
* Women can lead troops [...] if they are Iranian Zoroastrian (and have the Martial Lady trait) [...]
As aspiring Emperor of Persia, when I was still just king of Afghanistan, I declared Holy War to subjugate the steppe people around the old Karen lands (Khiva maybe).
Playing a great high martial ruler, I of course rode into battle - but when I checked, my flank commander was my wife! I could find no way to retire her and make her go home, so we fought the first battle together. Moving further into enemy territory, the event pops up telling me I got a daughter - born on the eve of battle, right there in the war camp!
I decided the girl should deserve a special name, so I added "stirrup" as sort of a nickname. Sadly, she died a few days later - guess medical treatment isn't that good in a war camp :/
Anyway, this had great potential for an AAR ^^