Gums bleed when they are irritated and inflamed which is not considered normal. This is due to plaque (a soft film of bacteria) being left on the teeth which causes inflammation called gingivitis and if not addressed can develop into gum disease. Over time, if not cleaned off through daily brushing and interdental cleaning, the plaque can turn into a hard deposit called tartar or calculus which will require professional scaling by your dentist or hygienist to remove it.
It is important even if your gums bleed they are still brushed to keep the mouth clean otherwise the bacteria build up in the mouth will make gum inflammation worse. After a few days of thorough cleaning, your gums should stop bleeding. If this does not happen you will need to ask the advice of your dental team as you may need professional cleaning.
A good oral care regime should be able to prevent your gums from bleeding if done correctly. We would always suggest that you have regular examinations at your dentist. This can help diagnose and treat anything unusual in your mouth so you get the correct care and advice.
You may have to use a softer brush whilst the gums are inflamed until they become healthier. It is also important to clean in between teeth daily using interdental brushes or floss.
Smoking can cover up a gum problem as it restricts the blood flow to the mouth. If you have recently given up smoking this could allow the gums to get a better circulation and therefore start to bleed.