# Day 144: The cervix-length question

> Twenty weeks and four days. Many women have their cervix measured by ultrasound between 20 and 24 weeks. Today you write down one question to ask about it.

- Series: Your fifth month of pregnancy, day by day (https://chorevia.com/learn/pregnancy-month-5), day 144 of 280, 20 weeks + 4 days
- Your baby this week: about the size of a banana; around 25.6 cm from head to heel
- Canonical URL: https://chorevia.com/learn/pregnancy-month-5/day-144
- Last reviewed: 2026-10-22
- Publisher: Chorevia (https://chorevia.com)
- Cite as: Chorevia. "Day 144: The cervix-length question." Last reviewed October 22, 2026. https://chorevia.com/learn/pregnancy-month-5/day-144

This guide is general education that summarizes published research and guidance from groups like the American Academy of Pediatrics, the CDC, and the WHO. It isn’t medical advice, and every child develops on their own timeline. Your pediatrician knows your child; if something feels wrong, call them. In an emergency, call 911.

Twenty weeks and four days. Today's note is about a measurement most people have never heard of. You don't need to understand it fully; you need one question on paper before your next scan.

## Your baby

Around 25.6cm long from head to heel, about the size of a banana, and getting more active by the day: kicking, punching and turning ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-20/)).

## Your body

Many women have their cervix length measured by vaginal ultrasound around 20 to 24 weeks ([MedlinePlus](https://medlineplus.gov/ency/article/003778.htm)). The reason is simple: the cervix typically shortens before it dilates, so its length can be an early clue to preterm labor ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000486.htm)).

Some things raise the chance of preterm labor, among them a previous preterm birth, surgery on the cervix such as a LEEP or cone biopsy, twins, and infection ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000486.htm)). Women with a prior preterm delivery may need weekly progesterone injections ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000486.htm)), and an NICHD-led study found progesterone cut the risk of another preterm birth by one third in women who'd had one before ([NICHD](https://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/complications)). Whether any of this applies to you is your provider's call.

## Try today

### The cervix-length question

- **Time:** 5 minutes now, 2 minutes at your visit

1. In your notes for the next scan or visit, write: "Is my cervix length being measured, and how?" ([MedlinePlus](https://medlineplus.gov/ency/article/003778.htm)).
2. Under it: "If it is, what does my number mean, and does anything change?"
3. Add anything they should know: a previous preterm birth, or cervical surgery like a LEEP or cone biopsy ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000486.htm)).
4. Write the answer down at the visit, in their words, before you leave the room.

**Make it work:** MedlinePlus's own advice on scans is to talk to your provider about the right schedule for you ([MedlinePlus](https://medlineplus.gov/ency/article/003778.htm)). Asking isn't second-guessing anyone.

## Watch for

- **Normal:** your bump tightening once in a while and then softening; some contractions through the day are normal ([NICHD](https://www.nichd.nih.gov/health/topics/preterm/conditioninfo/symptoms)). **Call your provider** immediately for more than 5 contractions an hour, or contractions that are regular and painful ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000486.htm)).
- **Normal:** gums that bleed when you brush ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-20/)). **Call your provider** for any vaginal bleeding; in months 4 to 9, MedlinePlus says to treat it as a potential emergency ([MedlinePlus](https://medlineplus.gov/ency/article/003264.htm)).
- **Normal:** feeling hot ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-20/)). **Call your provider right away** for fever or chills, or pain when you urinate ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000557.htm)).

## For you

Most people go through a whole pregnancy without ever hearing their cervix length out loud. If you're one of them, that's fine; the question still takes thirty seconds to ask. If you get a number and an explanation, you'll know more than you did, and you won't be lying awake guessing.

If a scan finds something that worries you, the NHS's advice is to talk your options through with a doctor or midwife ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-21/)). Bring a list, and bring someone.

If you're the partner: you're the note-taker at this one. She's lying on a table; you've got the pen.

## Sources

- NHS. "Week 20." Week-by-week guide to pregnancy, Best Start in Life. https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-20/
- MedlinePlus. "Ultrasound pregnancy." Medical Encyclopedia, National Library of Medicine, 2026. https://medlineplus.gov/ency/article/003778.htm
- MedlinePlus. "Preterm labor." National Library of Medicine. https://medlineplus.gov/ency/patientinstructions/000486.htm
- National Institute of Child Health and Human Development. "What are some common complications of pregnancy?" National Institutes of Health. https://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/complications
- National Institute of Child Health and Human Development. "What are the symptoms of preterm labor?" National Institutes of Health, 2023. https://www.nichd.nih.gov/health/topics/preterm/conditioninfo/symptoms
- MedlinePlus. "Vaginal bleeding in pregnancy." Medical Encyclopedia, National Library of Medicine. https://medlineplus.gov/ency/article/003264.htm
- MedlinePlus. "Prenatal care in your second trimester." National Library of Medicine. https://medlineplus.gov/ency/patientinstructions/000557.htm
- NHS. "Week 21." Week-by-week guide to pregnancy, Best Start in Life. https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-21/