Periods during pregnancy

Periods cycle explained

In a non-pregnant woman, there's a monthly cycle of female hormones which controls the release of an egg and causes the lining of the womb to thicken. If that egg isn't fertilised, hormone levels fall at the end of the month, and the womb lining breaks down and is shed as a period.

When a woman becomes pregnant, the cycle of hormones is usually lost. Hormone levels increase to stimulate the womb and make it ready to support the developing foetus. So, no womb lining is shed - and there are no periods during the pregnancy.

Periods during pregnancy

There are two possible explanations for periods during pregnancy:

Hormone levels. In some women, the hormone levels in pregnancy aren't high enough to prevent the lining of the womb being lost in those areas where the placenta isn't attached. So sometimes a woman will have one episode of bleeding or more in the first month or two of pregnancy (and, rarely, throughout the pregnancy).

The bleeding is because of something other than a period. For example, a pregnancy-related cause of bleeding, such as a tubal pregnancy, or another cause, such as polyps on the cervix. In these cases the bleeding isn't usually regular like a period.

If you are concerned, talk to your doctor. You may also want to do a pregnancy test. If your doctor suspects that the bleeding is because of another cause (besides periods), they may want to examine you or do further tests.