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 progestogen-only pill (mini pill)

There are two types of progestogen-only or POP pill.

How does the progestogen-only pill work?

One type mainly works by preventing sperm entering the womb and has a 3 hour ‘missed pill’ window. The other (any pill containing desogestrel only) mainly works by preventing an egg from being released and has a 12 hour ‘missed pill’ window.

Typical user failure rate is up to 9%. (Up to 9 women in 100 will have an unplanned pregnancy in the first year of use.)

Progestogen-only pill advantages

  • It may be suitable for women who do not want to or cannot take oestrogen for health reasons.
  • It may be suitable for women who are over 35 and women who smoke.
  • It can be used by women who are breastfeeding.

Things to consider

  • It has to be taken every day. If you miss a pill or take it late your risk of becoming pregnant will increase.
  • Women may experience irregular bleeding or their periods may stop.
  • Some medicines may affect the POP's effectiveness.
  • Vomiting or severe diarrhoea can make it less effective.
  • Does not protect against sexually transmitted infections.

Progestogen-only pill aftercare advice

If you start the pill after an abortion, or on the first day of a period, it will work straight away. If you start on any other day, use extra precautions or abstain from sex for 2 days. Do not stop taking it.

Irregular bleeding is a common side effect and periods can also stop which is nothing to worry about.

You can use this contraceptive following Marie Stopes UK abortion treatment