Many girls or women who carry the altered factor VIII (8) or IX (9) gene causing haemophilia (the "haemophilia gene") do not have symptoms of a bleeding disorder. If at least one of their X chromosomes has a factor VIII or IX gene that works, their body can usually produce normal or near normal levels of factor and they do not have bleeding problems.

However, some girls and women who carry this gene may have a bleeding tendency. They used to be described as “symptomatic carriers”. If their factor levels fall in the range for mild haemophilia (5 – 40% of normal clotting factor), they are now recognised as having mild haemophilia. In very rare cases, some girls or women have particularly low factor levels causing them to have moderate or severe haemophilia. Some women with factor levels between 40% and 60% of normal also experience abnormal bleeding.

Examples of having a bleeding tendency or symptoms may include:

  • Bruising easily
  • Heavy bleeding with menstrual periods (menorrhagia). This may lead to low iron levels or anaemia
  • Excessive bleeding after dental surgery or extractions, other surgery and medical procedures, injuries or accidents
  • Prolonged bleeding after childbirth (particularly with delayed or late postpartum haemorrhage)
  • Females with very low clotting factor levels may also have joint or muscle bleeds.

All females who carry the gene should have testing for their clotting factor levels. Ideally this should be done early in life so that females with low factor levels are identified and managed appropriately before they have problems with bleeding.

Unlike males with haemophilia, where the factor level is nearly always the same within the same family, the factor level in females who carry the gene is unpredictable and varies between family members.

Women and girls with lower levels should have theirs checked periodically, as their factor levels may change with age, pregnancy and hormonal medications. If their factor level is low, they will need a treatment plan to prevent bleeding problems and manage any situations that occur.

Date last reviewed: June 2016