Wow that makes me a ten ton tessie. I'm 5'3 3/4" and weigh about 116lbs.
It's about the heaviest 'healthy' weight I've ever been (fibroids aside, I don't know how much weight they add - I've been told they are 'large' that was 6 yrs ago.) I've weighed more but that wasn't due to fat - due to a malfunctioning body.
I weighed around 105lbs for a couple of years but I looked like a famine victim - not at all healthy. I put on the weight once I started running / swimming / cycling again and not just burning calories at the gym.
Like KK I'm big boned - I did one of those density tests that came out as medium build.
Not that any of this answers the OP's question. I've never had children but I've always had periods even when my weight was under 98lbs
I think Victoria Beckham is the person to ask. There were rumours that she had to gain weight in order to conceive.