Brushing and flossing your teeth is an important part of your daily health routine. This should not change in pregnancy. However, due to the increase in pregnancy hormones, specifically progesterone, you may notice that your gums become swollen and may even bleed when you brush or floss. This does not mean that you should stop brushing or flossing.
The bacteria that causes plaque is active in your mouth all the time. During pregnancy your body reacts differently to it and your gums become swollen, pregnancy gingivitis. So the "force" of the tooth brush or dental floss can irritate this area.
You should continue to brush your teeth with a soft sided tooth brush. This will clean your teeth and be gentle on your gums. Flossing is still important. Perhaps flossing with a more gentle motion is called for in your daily routine, but you should continue to floss. You should also see your dentist for any regularly scheduled cleanings or to ask for advice on handling pregnancy gingivitis.
Some studies indicate that improper oral hygiene in pregnancy can lead to preterm labor or premature birth from chronic periodontitis, an infection of the surrounding tissues in the gums. You may also notice a small nodule or cyst in your gums in pregnancy called a pyogenic granuloma. Your dentist can confirm that is what it is and it should not be painful but it may bleed.
Source:
Possible association between mother's periodontal status and preterm delivery. Radnai M, Gorzó I, Urbán E, Eller J, Novák T, Pál A. J Clin Periodontol. 2006 Nov;33(11):791-6. Epub 2006 Sep 13.
