No need to duck, a valid point, but actually the baby sits on the hip and isn't often carried with the arms alone, and babies are a little softer than aluminum or steel. So as light as a bike might get, many women of average stature will have trouble carrying it [video] if the bike has to be held out away from the body, requiring upper-body strength. And it's for that reason that I come back to what might seem a counter-intuitive suggestion, a heavier bike but one that is designed to be rolled not carried, and with a handle for when it has to be lifted: the Mobiky Genius has ads showing a woman rolling the folded bike by its extended seat-tube (recognizing this strength issue). And the Strida or Strida Mini as well would be good to consider. Both Mobiky and Strida could be used for leisure rides too, terrain permitting.

Regards
T