Have you discussed this with your obstetrician? A boil is usually an infected hair follicle, but repeated boils can be caused by an overgrowth of staph on your skin. Staphylococcus is a bacteria that is normally on everyone's skin. If you have an overgrowth for some reason, perhaps the changes in body chemistry that come with pregnancy, or a depressed immune system, then a tiny opening in the skin can let the staph go in and cause a little infection or boil. You can try keeping those areas extra clean, but that may not be enough. Your obstetrician may want to prescribe a special body wash or other treatment.
This is not an unusual problem, as one internet search will tell you. But staph can cause many infections even though it is a normal part of skin flora, so ask the obstetrician just to cover all your bases. We have a page on boils: https://www.empowher.com/condition/boils and so does Mayo Clinic: http://www.mayoclinic.com/health/boils-and-carbuncles/DS00466
Good luck, and congratulations on your pregnancy!