Pregnancy
A higher level of progesterone can cause exaggerated gingivitis from approximately the second month to the eighth month of pregnancy. Though you take excellent care of your teeth, you may still find that your gums bleed when you brush. For some women, gum tissue becomes so sensitive that an irritant (such as plaque) can make it swell into a large, mostly painless bump (called a pregnancy tumor) that usually goes away within a few months after delivery or can be removed by your dentist if it becomes bothersome.
Whether or not you experience gum sensitivity during your pregnancy, make a dental hygiene visit part of your prenatal care, as periodontal disease has been linked to pre-term birth and low birth weight babies.