What is implantation bleeding?
Our panel of health writers.
Once your egg is fertilised by sperm in your fallopian tube, it becomes a rapidly dividing bundle of cells called a blastocyst. The blastocyst travels down the tube towards your uterus.
Once there, it burrows into the wall of your uterus so that it can start developing into an embryo and placenta. As the blastocyst plants itself into your uterus wall, it can cause a small amount of bleeding.
It's hard to be certain about implantation bleeding happening, as it can occur around the same time that your period would have been due. Bleeding when your period is due is called breakthrough bleeding. As implantation bleeding and breakthrough bleeding can both cause a light bleed, it's hard to tell the difference between the two. It's thought that breakthrough bleeding is more common.
If you notice any bleeding, it is always best to see your midwife or doctor. Although early light bleeding, whatever the cause, is common, it may need further investigation.
Your midwife or doctor may recommend that you visit an early pregnancy assessment unit (EPAU) in hospital. Staff at this unit specialise in early pregnancy and can help to identify the cause of your bleeding.
At the unit you may have:
- your urine or blood tested to check your hormone levels
- an examination of your cervix
- an ultrasound scan to check your baby's heartbeat
Even if you think that your bleeding may be caused by implantation, it is always best to get it checked out.
ReferencesThis article was written using the following sources:
Everett C. 1997. Incidence and outcome of bleeding before the 20th week of pregnancy: prospective study from general practice. BMJ 315: 32-34
NGC. 2009. First trimester bleeding. National Guideline Clearinghouse (USA). www.guideline.gov [Accessed August 2013]
NHS.2013. What causes bleeding during pregnancy? http://www.nhs.uk/chq/Pages/938.aspx?CategoryID=54&SubCategoryID=134[accessed August 2013].
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