# Day 219: The mattress

> Thirty-one weeks and two days. A borrowed crib can be a fine crib, but the mattress matters most. Today you check it fits snugly and stays very firm.

- Series: Your seventh month of pregnancy, day by day (https://chorevia.com/learn/pregnancy-month-7), day 219 of 280, 31 weeks + 2 days
- Your baby this week: about the size and weight of a coconut; around 41.1 cm from head to heel
- Canonical URL: https://chorevia.com/learn/pregnancy-month-7/day-219
- Last reviewed: 2026-10-22
- Publisher: Chorevia (https://chorevia.com)
- Cite as: Chorevia. "Day 219: The mattress." Last reviewed October 22, 2026. https://chorevia.com/learn/pregnancy-month-7/day-219

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.

Thirty-one weeks and two days. Of all the baby gear on the list, the crib mattress is the one worth checking with your own hands. Today you do that.

## Your baby

Around now your baby is around 41.1cm long from head to heel, about the size and weight of a coconut ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/3rd-trimester/week-31/)). They're very active: moving, sucking their fingers, even doing somersaults ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/3rd-trimester/week-31/)). All that tumbling has a padded room. Soon they'll need a firm one.

## Your body

Getting a crib, carry cot, or Moses basket for the first few months is on the NHS list for this week. If you're borrowing a cot, it says to get a new mattress that fits snugly and is clean and waterproof ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/3rd-trimester/week-31/)). The AAP says the mattress should be "very firm and should not sag under your baby's weight," and fit snugly with no gap against the crib walls ([AAP](https://www.healthychildren.org/English/ages-stages/prenatal/decisions-to-make/Pages/Choosing-a-Crib.aspx)).

On bedding, the two countries differ. The NHS says no pillows or duvets, and suggests a baby sleeping bag or light blankets ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/3rd-trimester/week-31/)). The US Consumer Product Safety Commission says "Bare is Best": nothing but a fitted sheet, no pillows or blankets ([CPSC](https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/cribs)). The newborn guide follows the US rule.

## Try today

### The mattress fit test

- **Time:** 5 minutes
- **From the guide:** [Safe sleep, every sleep](https://chorevia.com/learn/newborn#safe-sleep-every-sleep)

1. Push the mattress hard against one side of the crib, then look along the opposite edge. There should be no gap against the crib walls ([AAP](https://www.healthychildren.org/English/ages-stages/prenatal/decisions-to-make/Pages/Choosing-a-Crib.aspx)).
2. Press your palm into the middle. It should feel very firm and not sag ([AAP](https://www.healthychildren.org/English/ages-stages/prenatal/decisions-to-make/Pages/Choosing-a-Crib.aspx)).
3. If it's borrowed, or fails either check, put a new snug mattress on the list ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/3rd-trimester/week-31/)).
4. Take everything out except one fitted sheet ([CPSC](https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/cribs)).

**Make it work:** Do this one together. A crib is the kind of job that's easy to hand to the partner with the free Saturday.

## Watch for

- **Normal:** an occasional headache that clears with rest and water. **Call your provider** right away for a headache that won't go away or gets worse over time, even with medicine and fluids ([CDC](https://www.cdc.gov/hearher/maternal-warning-signs/index.html)).
- **Normal:** tired, achy legs after a day on your feet. **Call your provider** right away for severe swelling, redness, or pain in one leg or arm ([CDC](https://www.cdc.gov/hearher/maternal-warning-signs/index.html)).
- **Normal:** feeling hot, which the NHS lists among late-pregnancy symptoms ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/3rd-trimester/week-36/)). **Call your provider** right away for a fever of 100.4°F (38°C) or higher ([CDC](https://www.cdc.gov/hearher/maternal-warning-signs/index.html)), and as soon as you can for chills ([OWH](https://womenshealth.gov/pregnancy/youre-pregnant-now-what/pregnancy-complications)).

## For you

Second-hand is fine for a lot of baby things. For the mattress, the NHS's answer is new ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/3rd-trimester/week-31/)), and that's one place where spending a little is worth it. A borrowed crib is also worth a quick recall check on SaferProducts.gov, which the CPSC points parents to ([CPSC](https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/cribs)).

## Sources

- NHS. "Week 31." 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/3rd-trimester/week-31/
- American Academy of Pediatrics. "Choosing a Crib." HealthyChildren.org. https://www.healthychildren.org/English/ages-stages/prenatal/decisions-to-make/Pages/Choosing-a-Crib.aspx
- U.S. Consumer Product Safety Commission. "Safe Sleep – Cribs and Infant Products." CPSC. https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/cribs
- 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
- NHS. "Week 36." 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/3rd-trimester/week-36/
- Office on Women's Health. "Pregnancy complications." U.S. Department of Health and Human Services. https://womenshealth.gov/pregnancy/youre-pregnant-now-what/pregnancy-complications