# Day 129: The dark line

> A brown line down the middle of your belly, darker patches on your face: normal, hormonal, and temporary. Today you note it and get on with your day.

- Series: Your fifth month of pregnancy, day by day (https://chorevia.com/learn/pregnancy-month-5), day 129 of 280, 18 weeks + 3 days
- Your baby this week: about the size of a bell pepper; around 14.2 cm from head to bottom
- Canonical URL: https://chorevia.com/learn/pregnancy-month-5/day-129
- Last reviewed: 2026-10-22
- Publisher: Chorevia (https://chorevia.com)
- Cite as: Chorevia. "Day 129: The dark line." Last reviewed October 22, 2026. https://chorevia.com/learn/pregnancy-month-5/day-129

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.

Eighteen weeks and three days. Somewhere around now, many women notice a faint line running down the middle of the belly that wasn't there before. It has a name, and it's going nowhere for a while.

## Your baby

Around 14.2cm from head to bottom this week, about the size of a bell pepper ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-18/)). The reflexes developing now, hearing, feeling, swallowing and sucking, are the ones a newborn arrives with ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-18/)).

## Your body

The NHS's week 18 page lists it as a normal change: a dark line down your stomach, the linea nigra, which usually fades months after the birth ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-18/)). The same hormone changes can bring brownish or yellowish patches on the face, called chloasma or the "mask of pregnancy" ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000611.htm)).

Sunlight darkens both, so MedlinePlus's advice is a hat, protective clothing, and sunblock, and to avoid concealers that contain bleaches ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000611.htm)). Stretch marks may be joining the picture: they affect up to 8 in 10 women and usually fade to silver after birth ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-17/)). Lotions and oils can't really prevent them, though avoiding excessive weight gain can lower the risk ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000611.htm)).

## Try today

### The dark-line note

- **Time:** 2 minutes

1. If you're taking bump photos, take this week's. If you aren't, take one anyway; it's week 18.
2. In the caption, write one line: "Dark line showed up." Date it.
3. Add anything else that's new on your skin: a patch on your cheek, a mark on your hip.
4. Close the app. That's the whole task. The line is normal and usually fades months after birth ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-18/)).

**Make it work:** Put sunblock by the front door today, where you'll see it on the way out ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000611.htm)).

## Watch for

- **Normal:** itchy skin as the belly stretches; about 20 percent of pregnant women feel itchy, and it typically resolves after delivery ([OWH](https://womenshealth.gov/pregnancy/youre-pregnant-now-what/body-changes-and-discomforts)). **Call your provider** for persistent itching without a rash, because it may indicate cholestasis ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000611.htm)).
- **Normal:** an ordinary headache that eases with rest; headaches are common in pregnancy, and ask before taking any medicine for one ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000580.htm)). **Call your provider** for a headache that won't go away or gets worse over time ([CDC](https://www.cdc.gov/hearher/maternal-warning-signs/index.html)).
- **Normal:** your eyes feeling tired at the end of the day. **Call your provider** for changes in your vision; they're an urgent warning sign ([CDC](https://www.cdc.gov/hearher/maternal-warning-signs/index.html)).

## For you

Most skin colour changes fade within a few months after birth ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000611.htm)). The OWH's line on stretch marks is the one to keep: "Be patient — stretch marks and other changes usually fade after delivery" ([OWH](https://womenshealth.gov/pregnancy/youre-pregnant-now-what/body-changes-and-discomforts)).

There is a small, loud industry built on telling you otherwise. Nothing in the pool of sources this series uses names a cream that prevents stretch marks or erases the line. Spend the money on the hat.

If you're the partner: if she shows you the line, "huh, cool" is a complete answer. It is not a problem to be solved.

## Sources

- NHS. "Week 18." 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-18/
- MedlinePlus. "Skin and hair changes during pregnancy." National Library of Medicine. https://medlineplus.gov/ency/patientinstructions/000611.htm
- NHS. "Week 17." 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-17/
- Office on Women's Health. "Body changes and discomforts." U.S. Department of Health and Human Services. https://womenshealth.gov/pregnancy/youre-pregnant-now-what/body-changes-and-discomforts
- MedlinePlus. "Aches and pains during pregnancy." National Library of Medicine. https://medlineplus.gov/ency/patientinstructions/000580.htm
- Centers for Disease Control and Prevention. "Urgent Maternal Warning Signs and Symptoms." HEAR HER campaign, 2024. https://www.cdc.gov/hearher/maternal-warning-signs/index.html