Following their maiden win of the 2019/20 campaign, a 3-0 victory at Lewes last weekend, the Foxes entertained the Blues in Quorn.
City were behind after 15 minutes as Rachel Williams capitalised on an error at the back before converting well, while Lucy Staniforth doubled the visitors' advantage before the half-time break.
In the space of two second-half minutes, meanwhile, it was four for Birmingham as Williams and then Adrienne Jordan struck, before Leicester were awarded a penalty on the hour-mark.
After herself being brought down in the area, Lachante Paul stepped up to fire her spot-kick into the roof of the net, however, Staniforth's second for Birmingham late on confirmed the 5-1 scoreline.
The Foxes next travel to The Oakwood to face Charlton on Sunday 17 November (2pm kick-off) in the FA Women's Championship, before visiting Manchester United in the Continental League Cup on Thursday 21 November (7:30pm kick-off).
The details...
City: Field, Everett, Morgan (c), Cataldo, Smith (Thomas 72'), Blanchard (Bailey-Gayle 72'), Paul, James (Jhamat 63'), Brown, Johnson, Popple
Subs not used: Lambourne, Taylor
Goal: Paul 62'
All times GMT.