Lots of things can happen to you while you're pregnant and your mouth is no exception. Bleeding and swollen gums are common. It's sometimes very challenging to keep your mouth clean when you are feeling ill and brushing can bring on gagging and even worse.
Still, it's important to have your teeth cleaned in the second trimester and home care is more important than ever. I recommend a very mild toothpaste and frequent short brushing throughout the day if the standard two minutes is too much. If you do get sick, don't brush right away. Rinse well with water and wait 20 minutes before brushing. This will insure that all of the stomach acid is off your teeth.
Of course you'll want to see a dentist right away especially if you haven't been in a while. The doctor won't advise you have dental x-rays unless there is an emergency dental infection such as an abscess. Dental treatment won't be done unless it is necessary to alleviate pain or infection.
If you do have periodontal disease it is necessary to perform the proper cleaning to protect your baby from the germs present in the mouth. The placenta is a great barrier, however, bacteria can cause inflammation in the body that could result in a premature delivery and your baby may be underweight.