Pregnancy, cervical screening and abnormal cervical cells

Routine cervical screening tests in pregnant women can be delayed until after they have had their baby. This is the advice from the NHS cervical screening programme. Pregnancy can make the result of the test harder to interpret and could be inaccurate.

Planning to become pregnant

If you're planning to become pregnant, check with your GP that you are up to date with your cervical screening. Then you can have the test, and if you need treatment, you can have it before you become pregnant.

Already pregnant 

If you are already pregnant, and are due to have a cervical screening test, you can usually wait to have the test until 3 months after your baby is born. When you are invited for your test, you should let your GP or clinic know that you are pregnant. They can then delay the test.

You may need to have a screening test while you are pregnant if you:

• have had abnormal results from a cervical screening test before
• haven't had a screening test in the last 3 to 5 years

Your GP or midwife might ask you to have the test between 3 and 6 months of pregnancy. This test is safe to have when you are pregnant.

If the results come back abnormal, or if a test you had just before you became pregnant shows abnormal results, you don't need to worry. This doesn't mean that you have cancer. It means there are some abnormal cells that can be easily treated a few months after birth.

If the abnormal test result is:

• low grade, you will be seen 3 months after you deliver your baby
• high grade, you will be examined during your pregnancy and treated 3 months after your delivery. A biopsy is only taken during pregnancy if cancer is suspected

You may need to have a colposcopy while you are pregnant. This is a close examination of your cervix and vagina. It is safe during pregnancy. It helps your doctor to see how much the cells on your cervix have changed.

Treatment for abnormal cells during pregnancy

Abnormal cervical cells are also called CIN 1, 2 or 3. It doesn't mean you have cervical cancer if your doctor says you have abnormal cells. But some of the abnormal cells could turn into cancer if left untreated.

Before giving birth

If you only have mild changes to the cells on your cervix (CIN 1), you won't need any treatment until 12 months later. After that, you may have another colposcopy to check the cervical cells again. Many women with mild changes go back to normal without any treatment.

CIN 2 or 3 are more abnormal. Your doctor may ask you to have another colposcopy to keep an eye on them when you are about 6 months pregnant. The abnormal cells are not likely to change much during your pregnancy.

If you are pregnant and your colposcopy shows that the cell changes have started to turn into cancer, your doctor will need to take a tissue sample. This is usually by a procedure called LLETZ (large loop excision of the transformation zone). But your specialist will not do this unless it's necessary.

After giving birth

If the cells on your cervix have not gone back to normal after you have given birth, you may then have treatment to remove them.

You can discuss your treatment options and any worries with your:

• GP
• midwife
• doctor
• specialist nurse at the colposcopy clinic

It's important to make sure that you go to all of your follow up appointments after you've had your baby.

Pregnancy after a cone biopsy

A cone biopsy removes a cone shaped wedge of tissue from your cervix. It can cause particular problems with future pregnancies. But these are not common.

Whether a cone biopsy might cause problems depends on the biopsy's depth. You can ask your doctor more about the chances of your biopsy causing problems with future pregnancies.

Narrowing of the cervix

After a cone biopsy, there is a very small chance that the cervix can narrow. This is called cervical stenosis. The cervix might become so tightly closed that sperm can't get in. If this happened, you wouldn't be able to get pregnant naturally.

If you're having periods after a cone biopsy, you do not have complete cervical stenosis. If the womb's lining can get out when it is shed as a period, sperm can get in. Some women may need surgery to stretch (dilate) the cervical opening.

Future pregnancies

Some treatments for CIN or very early stage cancer (stage 1A) can lead to a small risk of complications in future pregnancies. Women who have had a cone biopsy have:

• a higher chance of their babies being born before 37 weeks (preterm delivery)
• a higher risk of a baby that weighs less than 2.5kg (low birthweight)
• an increase in births by caesarean section

You may have an increased risk of early birth because the cone biopsy has weakened your cervix. The cervix muscle keeps the entrance to the womb closed unless you are in labour.

In some women who have had a cone biopsy, there is a risk that the cervix may start to open too soon because of the weight of the growing baby. Serious problems can usually be prevented.

If your doctor thinks your cervix may start to open too soon, you can have a sort of running stitch put around it to hold it shut. Your doctor may call this a purse string suture. The stitch is cut before you go into labour, usually at about week 37 of your pregnancy. The cervix can then open normally for the baby to come out.

Pregnancy after other treatment

It's very unlikely that the following other treatments for abnormal cells will affect your ability to get pregnant in the future:

• laser therapy
• cold coagulation
• cryotherapy

The most likely way that these treatments can affect your ability to get pregnant is if you get an infection after treatment, which spreads into your fallopian tubes.

Infection in the fallopian tubes can cause them to become scarred. If both your tubes are scarred, then your eggs can't travel down the tubes into your womb. This would mean that you couldn't get pregnant naturally.

Such a severe infection is unlikely after treatment for abnormal cells. See your GP straight away if you have any symptoms of infection. These can include:

• heavy bleeding, especially if it's more than during a period
• a vaginal discharge that smells or is green or yellow in colour
• period like pains that last more than a day or two
• a high temperature (fever)

Large loop excision of the transformation zone (LLETZ)

With LLETZ there is a risk of birth before 37 weeks and having a low birth weight baby. This risk can depend on the amount of cervical tissue that has been removed.

A single loop excision measuring less than 10mm in length or depth doesn't usually cause your waters to break early. This is also called premature rupture of membranes. But there is a slight increase in the risk if you've had deeper or more treatments with LLETZ.

If you are pregnant, you should let your midwife or doctor know if you have had treatment for abnormal cervical cells. You may need a cervical length check if you had a treatment which removed more than 10mm of your cervix.

What to remember

You may feel worried about these risks, but remember:

• the risk of developing severe side effects during pregnancy is small
• if you have cervical abnormalities, having treatment is very important
• your doctor will talk through the treatment options and discuss any potential risks to future pregnancies