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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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What medicines might affect my contraception?

There are some medicines that can affect how your combined pill, patch, ring, progesterone-only pill or implant works. Be aware of them.

They are as follows.

  • Phenytoin
  • Phenobarbital
  • Primidone
  • Carbamazepine
  • Rifampicin
  • Oxycarbazepine
  • Topiramate
  • Felbamate
  • Griseofulvin
  • HIV medication
  • St. John’s Wort - a herbal rememdy

If you're only taking one of these tablets for a short while, you need to have stopped it for a minimum of 28 days for your contraceptive method to be effective. You can still reduce the risk of an unplanned pregnancy by using emergency contraception methods.