A weak pelvic floor is unfortunately a common problem and especially so for women who have had been pregnant and is further compounded by having numerous pregnancies and vaginal deliveries.
Symptoms of a weak pelvic floor can be stress urinary incontinence (leaking urine while laughing, sneezing and/or jumping) and/or pelvic organ prolapse (a pelvic organ descending into the vagina - this could be the bladder, the top of the uterus and/or the colon - and varies in severity based on how far the organ is descending).
Numerous medical studies have shown that activating the pelvic floor with a Kegel Contraction (named after the doctor who started to instruct his patients to activate their pelvic floors) can decrease symptoms of stress urinary incontinence.
Let's do a Kegel....so everyone has heard to squeeze as if you have to stop your urination...try that. Now let's add some imagery to that Kegel and see if you feel your pelvic floor contraction better....Imagine your vagina as a beautiful daisy flower and now draw that flower into a tight bud and lift the bud inside of you.... Did you feel like you activated your pelvic floor better? Hopefully you did!
Gravity matters and especially so if you have pelvic organ prolapse...so think of exercising with gravity eliminated or reduced. For example, having your bottom up on a cushion, or on a Pilates arc barrel or on a BOSU.
Another important concept is to strengthen the muscles which attach to your pelvis because if you strengthen these muscles you can indirectly increase the strength of your pelvic floor. To further increase the strength of your pelvic floor, you could add a Kegel exercise to the exercise. You do not need to do a Kegel on each repetition but every 3rd exercise or so - moderation is key - you want to strengthen your pelvic floor but also allow the pelvic floor to relax.
Here is a link to a Firm In 5 Exercises Workout Focus on Strengthening the Pelvic Floor done on the MINIMAX ( my patented version of the Pilates arc barrel) flipped over.