lots of stuff to think about when a woman has children:
are they all by the same father, or by a bunch of different guys? this will tell if maybe she had a long-term husband or boyfriend, or if she was just a little ho
someone else said the kids will always come first, very true. i once dated a girl who was always willing to ditch her responsibilities with her kids for me, this made me not respect her (i literally had to remove her from my house telling her to go home and send her kids off to school, she lived with her mother and expected her mom to take care of her kids).
some woman may use their children as an excuse for everything, so anything that may arise she can just say she has to do something with the kids, and to this you are 'expected' to just say ok.
she may be more stable because of her children, not a wild party girl. stability = better relationships.
she may be looking for a father figure, and being that you are most likely a 'built' guy, she envisions you as this figure. while this is not necessary bad, if its the only reason she wants you its not good.
personally i dont reject a girl who has kids. i get to know them and see whats the deal. some moms are great! some are awful. just gotta be willing to take a bit of time to find out