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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I’ve had unprotected sex – am I pregnant?

If you've had unprotected sex or think your contraception hasn't worked, you could be pregnant. You've also put yourself at risk of getting a sexually transmitted infection (STI). Read on to find out the facts of unprotected sex, what to do after you've had unprotected sex and where to get advice and help.

When can I get pregnant?

How can I prevent a pregnancy?

Emergency contraception

Where can I get emergency contraception?

Emergency contraceptive pill

The intrauterine device (IUD)

Marie Stopes emergency contraception appointments

Marie Stopes emergency contraception fees 

Unprotected sex and STIs

When can I get pregnant?

It's possible to get pregnant at any time of your monthly cycle. Although highly unlikely, you can even get pregnant when you're on your period. That's why it's important to have regular contraception sorted - not only will this reduce the risk of an unplanned pregnancy but also the chances of you getting an STI.

Important contraception fact: No contraception is 100% effective. But if you use it correctly (eg. don't miss taking contraceptive pills) it can be up to 99.9% effective. 

How can I prevent a pregnancy? 

Using contraception when having sex is always the best way to prevent a pregnancy. But if you've had unprotected sex or your contraception has failed (eg. you've missed taking a contraceptive pill or the condom split), emergency contraception can prevent a pregnancy from developing.

Important contraception fact: Emergency contraception can only reduce the risk of pregnancy when taken within 5 days of having unprotected sex.

Emergency contraception

If you've had unprotected sex within the last 5 days and don't want to be pregnant, emergency contraception can prevent a pregnancy from developing.

Emergency contraception can be used to reduce the risk of pregnancy in these situations: 

  • when contraception has not been used during sex 
  • contraception may have failed (e.g. missed taking contraceptive pills, condom split or came off)
  • sexual assault has occurred.

Where can I get emergency contraception?

You can get emergency contraception for free from GPs, NHS walk-in centres, Brook services (for under 25s) and sexual health clinics.

Marie Stopes also provides emergency contraception - the emergency contraceptive pill 'Ella-One' and the IUD. We can arrange an urgent appointment for you with minimum waiting time - call us on 0845 300 0460 (24 hrs) to find out more. 

Emergency contraceptive pill

The emergency contraceptive pill is also known as the 'morning after pill'. Marie Stopes UK offers Ella-One, which can be taken up to 5 days (120 hours) after unprotected sex. 

How does the 'morning after pill' work?

It delays ovulation (release of an egg) and causes some changes to the womb lining, which reduces the chance of pregnancy. It's not the same as the abortion pill as it acts to prevent pregnancy, not terminate an existing pregnancy.

How effective is the 'morning after pill' at preventing pregnancy? 

It has been shown to prevent up to 85% of unwanted pregnancies and is more effective taken closer to the time of unprotected sex. 

What are the side effects from taking the 'morning after pill'?

The most commonly reported side effects are minor abdominal pain and cramps, as well as some irregular vaginal bleeding. You may experience your period a little earlier or later than usual. If your period is late by more than a few days, you'll need to do a pregnancy test

Will the ‘morning after pill’ interact with my other medications? 

The morning after pill can be made less effective by medications including St. John’s wort and those used for epilepsy. Before taking the pill, you should discuss your medications with your GP or other healthcare professional. 

The intrauterine device (IUD)

An IUD is a small T-shaped plastic and copper device that’s inserted into your womb (uterus) by a specially trained doctor or nurse. The IUD may be appropriate if it's less than 5 days since you had unprotected sex. It's the most reliable form of emergency contraception, and may be appropriate if you are planning to use an IUD for future contraception. 

We can arrange for you to have an IUD fitted at Marie Stopes as an emergency contraceptive appointment - call us on 0845 300 0460 (24 hrs) to find out more.  

How does an IUD work?

The IUD works by stopping the sperm and egg from surviving in the womb or fallopian tubes. It may also prevent a fertilised egg from implanting in the womb. The IUD is a long-acting reversible contraceptive (LARC) method. This means that once it's in place you don't have to think about it each day or each time you have sex. 

You can use an IUD whether or not you've had children.  

How effective is an IUD as an emergency contraceptive?

The IUD is the most effective form of emergency contraceptive. If inserted within 5 days of unprotected sex, it can prevent up to 99.9% of unplanned pregnancies. It's also an effective long acting reversible contraceptive and can be left in for 5 or 10 years depending on which type is used.

How is the IUD inserted - will it hurt?

  • An experienced sexual health doctor will fit your IUD if you choose to have it inserted at Marie Stopes as emergency contraception. We can answer any questions you might have and will explain all of the benefits and risks of having one fitted. 

  • After your discussion, you'll be asked to remove your lower garments and lie on a gynaecological bed. We may ask you to put your legs in stirrups - this makes the procedure quicker and easier. 

  • We'll examine you first to assess the size of your uterus (womb) and where your cervix is. We'll then place a speculum in the vagina so we can see your cervix. We'll place a local anaesthetic gel on your cervix and clean the area.

  • We'll then grasp your cervix with a special instrument, measure the length of the uterus and insert the IUD. During this part of the procedure, you may experience some discomfort - like a menstrual cramp. Most women tolerate the procedure well and have no issues. If at any stage you feel uncomfortable, please tell the doctor.

  • The procedure is simple and takes less than 10 minutes.

Are there risks to having an IUD inserted?

  • There is a small risk of infection. if you have not had swabs done, we may give you antibiotics at the time of the procedure to minimise this.

  • There is a small risk of perforation of the uterus. For this reason, we ask you to feel for the IUD strings to ensure that the IUD is in place. 

  • Some women find they have some menstrual cramping and spotting after an IUD is inserted. This usually settles in 24-48 hours, but if it persists please call us on 0845 300 0460 (24 hrs).

  • Some women say they have slightly heavier periods with a copper IUD in place.

  • If you have not had a period within four weeks of having your IUD inserted for emergency contraception, you will need to do a pregnancy test.

Marie Stopes emergency contraception appointments

We offer emergency appointments for women who would like to speak with a doctor, buy the emergency contraceptive pill or have an IUD inserted. Call us on 0845 300 0460 (24 hrs) and we can arrange an urgent appointment for you.

Marie Stopes emergency contraception fees

View our full range of contraception services and fees by clicking here

Unprotected sex and STIs

Important contraception fact: Emergency contraception does not protect you against sexually transmitted infections (STIs). If you've had unprotected sex, you should get tested.

Sexual health clinics offer free and confidential testing. Find you nearest one by clicking here

Marie Stopes also offers STI testing. Find out more about Marie Stopes STI screening services by clicking here

Want to talk about your options? 

Call us anytime on 0345 300 8090 (24 hrs) for more information and appointments.