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 combined pill

The combined pill works by preventing the ovaries from releasing an egg each month (ovulation). It thickens cervical mucus so that it is harder for a sperm to reach the womb and thins the lining of the womb.

Typical use failure rate is up to 9%. (Up to 9 women in 100 will have an unplanned pregnancy in the first year of use). Most combined oral contraceptives are taken every day for 21 days followed by a 7 day break. Some preparations are taken slightly differently. 

Combined pill advantages 

  • The combined pill can sometimes be used to treat period pain, heavy periods, premenstrual syndrome, acne and endometriosis.

Things to consider about taking the combined pill

  • The combined pill is not suitable for women with high blood pressure.
  • It is not suitable for women over 35 who smoke.
  • It may not be suitable for women who have migraines.
  • Missing pills, taking some other medications, vomiting, or severe diarrhoea can make it less effective.
  • Side effects include mood swings, breast tenderness and headaches.
  • There is a small risk of blood clots.
  • It does not protect against sexually transmitted infections.

Aftercare advice

If you start the combined pill on the first day of a period or after an abortion, it will work straight away. If started on any other day of the cycle, extra precautions such as condoms or abstaining from sex should be used for seven days.

Take it for 21 days at about the same time each day, and then have a 7 day break. During the break you should have a bleed but it is usually lighter, shorter and less painful than a usual period. On the 8th day, start the next pack (the starting day of the week for each pack should always be the same if you are taking it correctly). It is common to spot bleed during the first pack of pills. Do not worry, it will still be effective.

You can use this contraceptive after Marie Stopes United Kingdom abortion treatment.