Gestation Calculator

This calculator has been designed to give you an idea of the treatment options available to you*. If you decide to have an abortion with Marie Stopes UK, one of our nurses will give a more approximate gestation date during your appointment by way of a scan.
*Please note that this online calculator will only give you an estimated gestation based on the details you have provided.

Please select the first day of your last menstrual period.



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The IUS (hormonal coil, Mirena)

The IUS, hormonal coil or ‘Mirena’ is a small plastic device fitted into the uterus through the cervix using a simple procedure that takes a few minutes.

How does the IUS work?

It slowly releases progestogen and works by stopping sperm meeting an egg or it may stop an egg implanting in the uterus. In some cases, it can stop ovulation (stop an egg being released).

The contraceptive implant is a long-acting reversible contraceptive (or LARC). These types of contraception are recommended by Marie Stopes United Kingdom, as they are over 99% effective – they’ve been shown to be 20 times more effective than short-term contraceptive methods such as the pill, patch or vaginal ring.

Long-acting methods of contraception all have the advantage that, once in place, you don’t need to think about them until they need replacing and none of them interrupt sex.

IUS advantages

  • It lasts five years but can easily be removed.
  • Periods usually become lighter, shorter and less painful.
  • Fertility returns immediately after it’s removed.

Things to consider

  • Unlike condoms, it does not protect from sexually transmitted infections.
  • It requires a simple small procedure to fit and remove.
  • There may be some abdominal pain for a few days as the ISU settles.
  • Common temporary side effects include spotty skin, headaches and breast tenderness.
  • You will need to see your GP or family planning clinic 6 weeks after fitting for a coil check.
  • Irregular spotting or bleeding is common within the first six months.
  • After an average of 6 months, periods may be much lighter or even cease completely. This is nothing to worry about and your coil will still be effective.

IUS aftercare advice

If you have an IUS fitted at the time of an abortion or on days 1-5 of a period it will work straight away. If fitted on any other day, use condoms or abstain from sex for seven days. Please see your GP or attend your family planning/sexual health clinic after 6 weeks to have your IUS checked.

checking IUS Mirena threads hormonal coil

Once a month, after your period, gently insert a finger into your vagina during a bath or shower. The neck of your womb (cervix) feels a bit like the end of your nose, and you should be able to feel the threads of your IUS. If you can’t, please see your GP or attend your family planning/sexual health clinic and use condoms or abstain from sex until the presence of the IUS is confirmed.

Your partner should not be able to feel the threads during sex. If this happens, seek advice as above, as your threads might be too long.

You can have this contraceptive fitted after Marie Stopes UK abortion treatment. Marie Stopes UK will only offer removal for medical complications.

Available download:

PDF icon LARC leaflet.pdf1.69 MB