Can weak stomach muscles cause a weak bladder or problems with urinary function?
More likely it is weak pelvic floor muscles. You can do exercises to strengthen them. Just sqeeze/contract all the muscles around your bottom and crotch area as though you are trying to hold in a wee. Hold this for a couple of seconds then repeat the exercise. Do this as many times a day as you can. Sitting, standing when ever you think of it. The more times you do it the better. It would be a good idea for you to discuss this with a doctor as the problem might be caused by something else and you could need other treatment.