Contraceptive Implant - How it works and who can have it

How does the contraceptive implant work?

The progestogen hormone in the implant is called etonogestrel. It is released into the bloodstream at a slow, steady rate.

The progestogen works mainly by stopping the release of the egg from the ovary. It also thickens the cervical mucus which forms a plug in the neck of the womb (cervix). This stops sperm getting through to the womb (uterus) to fertilise an egg.

It also makes the lining of the womb thinner. This means that if an egg were to fertilise, it would not be likely to be able to attach to the womb (implantation).

In order for you to get pregnant you need all of these things to be working (ovulation, sperm getting through the cervix, and implantation). The contraceptive implant blocks all three stages.

How quickly does the contraceptive implant work?

If an implant is put in during the first five days of your period, you are protected against pregnancy immediately.

If an implant is put in at any other time during your cycle, you are not protected until seven days have passed. You will need to use additional contraception is you wish to be sexually active during this time.

You can only have an implant put in if it is certain that you are not already pregnant.

Is there anyone who should not have a contraceptive implant?

Most women can have an implant fitted but there are a few exceptions. You should not have a contraceptive implant put in if you think you might be pregnant, or if you don't want to use a contraceptive method that might affect your periods.

You also should not use the contraceptive implant if:

  • You are taking medicines which might interfere with the implant.
  • You have heart or liver disease.
  • You have had breast cancer in the previous five years.
  • You are currently experiencing unexplained vaginal bleeding.
  • You have a hereditary blood disorder called porphyria.

There are some conditions which, if you have them, mean that you could use the contraceptive implant, but a different method might be more suitable for you. These include:

  • You are going to have major surgery with prolonged immobilisation.
  • You have an increased risk of blood clots in the veins due to antiphospholipid syndrome, antithrombin deficiency or factor V Leiden. You have previously had a deep vein thrombosis or pulmonary embolism.
  • You have migraines.
  • You have systemic lupus erythematosus.
  • You have gene mutations associated with breast cancer - for example, BRCA1.
  • You have cervical cancer.
  • You have experienced a stroke, angina or heart attack.
  • You have several risk factors for heart disease, such as smoking, high cholesterol, high blood pressure, diabetes.
  • You have had jaundice or itching caused by previous use of a hormonal contraceptive.

Can a contraceptive implant be used straight after having a baby?

You can have an implant after having a baby. If the implant is put in any time up to day 21 after you gave birth, you are protected immediately.

If the implant is put in later than day 21, you can still have it but will need to use additional contraception for the first seven days after it is put in.

Can a contraceptive implant be used when breast-feeding?

Yes, an implant can be used when breast-feeding. The implant will not affect your milk production and will not harm your baby.

Although breast-feeding does slightly reduce the chance of another pregnancy, it is not a reliable contraceptive and it is possible to become pregnant whilst breast-feeding.

Can a contraceptive implant be used after a miscarriage?

Yes, an implant can be used straight after miscarriage or termination of pregnancy if this is what you would like. You will then be immediately protected against pregnancy.

Can the contraceptive implant be used after emergency contraception?

The contraceptive implant is not an emergency contraceptive. However, if you have had unprotected intercourse and take emergency contraception such as the 'morning after' pill, you can have an implant to cover you into the future at the same time.

The length of time for which you need to use additional protection depends which emergency contraceptive you used. It is for seven days after levonorgestrel and 14 days after ulipristal.

If you do not have a period within three weeks you should do a pregnancy test.

If I have a contraceptive implant, what do I do when I want to try to get pregnant?

If you want to try for a baby, you need to have the implant removed. Your periods will return to normal, although it can be up to three months before you get back to your old rhythm. However, it is possible to get pregnant before you have your first period. 

Start pre-pregnancy care such as taking folic acid and stopping smoking beforehand. You can ask your doctor or nurse for further advice.

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Dr Mary Lowth
Peer Reviewer:
Dr Jacqueline Payne
Document ID:
4575 (v42)
Last Checked:
22 August 2017
Next Review:
05 July 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.