There is a change of hormones in your body during pregnancy, and this change can create swelling and inflammation of your gums, called pregnancy gingivitis. The change in hormones can also make it easier for bacteria to grow, which can lead to the puffy, red and swollen gum tissue. Pregnancy gingivitis can occur in any trimester of pregnancy but is most common in the second and third trimester. With proper oral hygiene, pregnancy gingivitis usually subsides on it’s own after birth and nursing, but in rare cases, if left untreated, it can progress into more severe gum disease, which leaves permanent complications with the supporting structures of your teeth.