I second taking cranberry extract pills. Also, if you can, eat berries--blueberries, raspberries especially, as they also have the same compound as cranberry (which makes it much harder for germs to adhere to the urinary tract--so they flush out instead).
But repetitive UTIs to me is a sign of a chronic systemic imbalance--if you are to get real relief from UTIs, you need to correct your pH as your U-tract (and possibly vagina and possibly your whole system) is too basic, needs to be more acidic.
I would take a high quality probiotic, for one. Also, the cran extract pills for at least a full month if not longer (it's advised against taking them perpetually, however, as it can lead to kidney stones). Drink, drink drink plenty of water--but no need to overdo it either. Yes, avoid sugars and caffiene if you aren't already doing so. Get vinegar into your diet--whether as salad dressing or as 'medicine' (by eating 1-2 tablesp, 1-3 times a day).
DO NOT 'hold your pee til later'--take potty breaks often to keep your system flushing well. Try to pee, and maybe rinse yourself off as well, after sex (semen is very basic).
To help kill off pathogens living in your UTract, a good idea while you're trying to change your pH, consider upping your Vit C to at least 2-3000 mgs a day, and also taking echinacea tincture for a month or so. This will boost your immune system.
Taking antibiotics, especially with any frequency at all, clearly does NOT do a dang thing to 'cure' or 'prevent' UTIs (or frequent ear infections or anything!) and only helps to keep your pH out of whack (which is why ppl get thrush/yeast, which loves basic conditions). Regular/frequent antibiotic use is also very likely to produce antibiotic-resistant strains of bacteria in your system and your environment that can be highly damaging and even deadly ("superbugs"). It also suppresses immune system functioning, another very bad idea and one guaranteed to make you dependent upon antibiotics. (I will add that where MS is concerned, I'm not well-versed--I'm speaking here of 'general population'). Antibiotics do certainly have a place in the 'medicine cabinet'--a VERY small place, one FAR smaller than what most docs and consumers give them.
Their are a host of natural UTI remedies, not all mentioned here. My main point is that repetitive UTIs, while they do occur for some women, are NOT 'normal' in pregnancy or otherwise. It is a sign at least of depressed/suppressed immune system, and also of pH imbalance that only 'feeds' the pathogens while keeping out the beneficial bacteria that we need for health ('acidophilus' family, what is found in yogurt, probiotics). If you can correct your pH, and re-institute colonies of beneficials in your system, you will have far less trouble with UTI or any illness.