Cervix

The lower part of the uterus that connects to the vagina. It opens slightly during menstruation and dilates during childbirth.

The cervix is a small opening inside the body, at the top of the passage between a girl's or woman's legs. It connects to the womb. It opens a little during periods and stretches wide during childbirth.

Simplify

The cervix is the lower part of the (womb) that connects to the top of the . It's like a narrow passageway with a tiny opening. It plays a big role in , , and childbirth, and it's also where cervical screening (smear tests) checks for abnormal cells.

The cervix sits at the top of the vagina, at the bottom of the uterus.
It has a small opening that lets period blood through and widens during childbirth.
Cervical screening (smear tests) check for cell changes that could lead to cervical cancer.
The vaccine, offered in schools in the UK, protects against the main causes of cervical cancer.

[DIAGRAM: Labelled cross-section of female reproductive system with cervix highlighted, showing its position between vagina and uterus]

What it does

The cervix acts as a gatekeeper between the vagina and the uterus. Its opening (called the os) is usually tiny — about the width of a thin straw. During a period, it opens just enough to let menstrual blood pass through. During childbirth, it dilates (stretches open) to about 10 centimetres to let the baby through. Outside of these times, it stays mostly closed.

The cervix also produces mucus that changes throughout the . Around , the mucus becomes thinner and slippery to help travel through. At other times, it's thicker and acts as a barrier.

Why it comes up in health conversations

The cervix is relevant to a few important health topics:

Cervical screening (smear tests) — in the UK, people with a cervix are invited for screening from age 25. A small sample of cells is taken from the cervix to check for changes that could, if left untreated, develop into cervical cancer. It's quick, and while it can be a bit uncomfortable, it's one of the best ways to catch problems early.

HPV and the HPV vaccine — most cervical cancers are caused by certain strains of HPV (human papillomavirus), a very common virus passed on through sexual contact. The HPV vaccine is offered to all young people in Year 8 (age 12-13) in the UK and protects against the highest-risk strains. Getting vaccinated before you're sexually active gives the best protection.

— some types of (like the IUD or IUS) are inserted through the cervix into the uterus by a healthcare professional.

Things people get wrong

"You can feel the cervix during sex." Sometimes, yes — deep can hit the cervix, and for some people this is uncomfortable or painful. The position of the cervix changes throughout the menstrual cycle (it sits higher or lower at different times), which is why the same position might feel fine one week and uncomfortable the next.

"Smear tests are only for older people." Screening starts at 25 in England (and 25 in Scotland, Wales, and Northern Ireland [CHECK: NI screening age]), but being aware of the cervix and cervical health matters earlier than that — especially since the HPV vaccine is given at 12-13.

Things people ask about the cervix

Can a tampon get lost past the cervix?

No. The opening of the cervix is far too small for a tampon to pass through. A tampon might move up in the vagina and feel hard to reach, but it can't go further than the cervix. If you're struggling to remove one, a GP or nurse can help — it's something they deal with regularly.

Does hitting the cervix during sex hurt?

It can. Some people find deep penetration uncomfortable because it puts pressure on the cervix. Changing position or angle usually helps. If it keeps happening and is painful, it's worth mentioning to a doctor.

Why do I need the HPV vaccine if I'm not having sex?

The vaccine works best when given before any exposure to HPV, which is why it's offered at 12-13. It's not about whether you're sexually active now — it's about protecting you for the future.

Where to get help

Your GP or school nurse — for questions about the HPV vaccine or any concerns about cervical health.
Jo's Cervical Cancer Trust — information and support about cervical screening, HPV, and cervical cancer.
NHS 111 — for advice if you're experiencing symptoms like unusual bleeding or pain.

The cervix is a small, narrow opening deep inside the body. It sits at the top of the passage between a girl's or woman's legs, and connects that passage to the womb.

Most of the time, the opening is very tiny. During a , it opens just enough to let blood through. During childbirth, it stretches open much wider to let the baby out.

The cervix also makes a sticky fluid called mucus. This fluid changes during the monthly cycle. Sometimes it's thin and slippery, which helps travel through. Other times it's thicker and blocks things from getting in.

The cervix matters for health because doctors can check it for early signs of cancer. This check is called a smear test, and people are invited for one from age 25 in the UK. There's also a vaccine given in schools around age 12-13 that protects against the main virus that causes cervical cancer.

Some types of long-lasting birth control are placed through the cervix into the womb by a doctor or nurse.

During sex, deep movement can sometimes bump the cervix, which can be uncomfortable. Changing position usually helps.

Vagina

The internal muscular canal connecting the vulva to the cervix. It's elastic and changes size depending on arousal.

The vagina is the stretchy passage inside a girl's or woman's body that connects the outside to the womb. Period blood comes out through it, and it's where a baby passes through during birth. It's different from the outside part, which is called the vulva.

Uterus

The organ where a baby grows during pregnancy. The lining sheds each month as a period.

The uterus (also called the womb) is the organ inside a girl's or woman's body where a baby grows during pregnancy. Each month, it builds up a soft lining. If no pregnancy happens, that lining comes out as a period.

HPV

Human papillomavirus. The most common STI globally. Some strains cause genital warts, others are linked to cancer. A vaccine is available.

HPV is the most common infection passed on through sex. Most types are harmless and your body gets rid of them on its own. Some types can cause genital warts. A few types can lead to cancer. There's a vaccine given in schools to protect against it.