Loose skin/pudge between ducks legs?

[Beanfox]

Wondering about my female ducks with loose skin or pudge between their legs? I suppose lower bellies would be more accurate.

I just really noticed it this week. Only showing in 5 of our females (we have 14) - our 3 youngest and 2 others

Is this a sign of overweight? Health issues? Or is it just something that happens when the females are laying eggs?

Ours started laying again late January/beginning February.

I tried to google but was getting results for unrelated things

 

[Beanfox]

Just to add, I do have calcium out for them. The oyster flakes, seems to be their fav