TLDR; what’s the lowdown?
- The implant (Nexplanon) is more than 99% effective so the chances of getting pregnant with the implant in your arm is fewer than 1 in 100
- You should be protected against pregnancy immediately if the implant in inserted into your arm during the first 5 days of your cycle – any later and you’ll need to use a barrier method
- The implant can cause lighter or fewer periods which is why some women may be concerned they are pregnant – don’t worry, it is a common side effect!
- Certain medications can make the implant less effective so always ask your doctor or get in touch with the Lowdown contraceptive experts
- Nexplanon should be replaced after three years to maintain effectiveness
The contraceptive implant is a method of contraception that stays in the upper arm for three years – perfect for those who don’t want to have to remember to take a daily pill.
But how effective is it, and can you still get pregnant on the implant?
In short, the implant is more than 99% effective. This means that fewer than 1 in 100 women with the implant will get pregnant each year.
There are some other factors to consider when using the implant as contraception such as side effects and its use with other medication.
Below our medical experts answer your most common questions covering the below topics…
What is the contraceptive implant?
The plastic device is about the size of a matchstick. The implant is a highly effective method of contraception but can have some side effects which can include changes to your periods, as well as tender breasts and mood swings for example.
How does the implant work?
The contraceptive implant works by slowly releasing a hormone called progestogen into your bloodstream which stops you from releasing an egg each month.
It will also thicken the mucus in your cervix, making it much more difficult for sperm to travel, and also thin the lining of your womb making it harder for a fertilised egg to implant. This makes the implant more than 99% effective according to the NHS.
Does the implant stop periods?
The implant can have an effect on your menstrual cycle. Periods may become lighter, heavier, longer, irregular or stop completely (also known as amenorrhoea). Whilst this isn’t something to worry about, it’s definitely something to consider before opting for this form of contraception.
When does the contraceptive implant start working to protect against pregnancy?
The implant can be inserted any time during your menstrual cycle. If the implant is inserted at the beginning of your menstrual cycle (the first five days) then you should be protected against pregnancy immediately.
If the contraceptive implant is fitted on any other day of your menstrual cycle then you will need to ensure that you use another method of contraception such as condoms for 7 days.
When does the contraceptive implant start working after giving birth?
After giving birth you are able to have the implant fitted any time and it is fine to use if you are breastfeeding. If fitted up to 21 days after giving birth you will be immediately protected against pregnancy. If the implant is fitted after 21 days, you will need to ensure that you use another method of contraception such as condoms for 7 days after the implant is fitted.
Can the contraceptive implant cause infertility?
The implant will not affect a woman’s fertility. As soon as the implant is removed her underlying fertility will return.
Can you get pregnant on the implant?
As this method of contraception is more than 99% effective, it is very rare that you will get pregnant on the contraceptive implant. As the implant stops ovulation this means that there is also no egg to fertilise.
What about if I am being prescribed certain medications?
There are certain medications that will make the contraceptive implant less effective. This includes some HIV, epilepsy and tuberculosis medications, St John’s Wort and certain antibiotics such as rifabutin or rifampicin.
We recommend having a conversation with your doctor to ensure that any medication you are taking will not affect the effectiveness of your implant. If your medication does affect this method then we would recommend looking for another method of contraception that isn’t affected by your medication.
Unsure which method is right for you? Speak to our doctors at The Lowdown and get personalised contraceptive advice.
Does taking antibiotics effect the implant’s effectiveness?
Most antibiotics are completely safe to take with the contraceptive implant and will not affect its effectiveness. But there are certain antibiotics such as Rifabutin or Rifampicin that may make the implant less effective. Ask your GP for advice about this if you are prescribed new medicines.
How long does the implant last and can you get pregnant on Nexplanon if it has expired?
Nexplanon can be used for three years, at which point it should be replaced to maintain its effectiveness. We recommend contacting your GP or sexual health clinic to discuss the replacement of your contraceptive implant prior to the date it is due to be replaced (so keep a diary or reminder). Due to Covid-19 restrictions you may not be able to attend for a face to face appointment to replace your implant. There is some evidence to say the implant remains effective up until four years, but a discussion with your doctor or nurse will help you work out what is best for you.
How will I know if I’m pregnant with the implant in my arm?
On the rare chance that you may become pregnant on the implant, it is recommended that you look out for certain signs. Looking out for a change in your period is not a good indicator of pregnancy as one of the side effects of Nexplanon is changes in the menstrual cycle. You may experience tiredness, nausea and tender breasts. If you are concerned you may be pregnant, we recommend taking a pregnancy test before contacting your GP.
I want to get pregnant but I have the implant – what next?
If you want to get pregnant and therefore no longer need a form of birth control, you should book an appointment with your GP to remove your implant. Actively trying to get pregnant with the implant still in your arm is not recommended as there is a higher risk of an ectopic pregnancy (see below).
What happens if I get pregnant on the implant?
In the very rare chance you become pregnant whilst using the contraceptive implant then you should contact your doctor. If you become pregnant whilst on Nexplanon, then you have a slightly higher risk of an ectopic pregnancy (outside of the womb). If you experience unusual vaginal bleeding or lower stomach pain then you must call your doctor immediately. The Nexplanon implant should be removed if pregnancy occurs, but there is no evidence to suggest falling pregnant whilst using the implant poses any harm to the developing pregnancy.
Can I get pregnant after implant removal?
Once the contraceptive implant is removed your normal fertility will return to normal and you may be at risk of pregnancy. If you would like to learn more about the process of removing the implant, then check out our full guide on contraceptive implant fitting and removal.
If you’re looking for further information on this form of contraception, then our blog on ‘the contraceptive implant – everything you need to know’ covers fitting and removal plus pros and cons of this method of contraception.
Faculty of Sexual and Reproductive Health
Reviewed and edited on 04/02/21 in line with our content policy.