# Day 91: Trimester two

> Thirteen weeks: the second trimester begins. Today you write down what you hope changes over the next fifteen weeks, and date it.

- Series: Your third month of pregnancy, day by day (https://chorevia.com/learn/pregnancy-month-3), day 91 of 280, 13 weeks
- Your baby this week: about the size of a peach; around 7.4 cm from head to bottom
- Canonical URL: https://chorevia.com/learn/pregnancy-month-3/day-91
- Last reviewed: 2026-10-22
- Publisher: Chorevia (https://chorevia.com)
- Cite as: Chorevia. "Day 91: Trimester two." Last reviewed October 22, 2026. https://chorevia.com/learn/pregnancy-month-3/day-91

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.

Thirteen weeks. A new trimester starts today, on paper at least. Today is a short note to yourself about what you hope the next stretch brings, sealed and dated.

## Your baby

Around now your baby is around 7.4cm long, about the size of a peach ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-13/)). The ovaries or testes are fully developed inside, and the final changes are happening on the outside ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-13/)). The movements are jerky and random at first, and become more deliberate ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-13/)); you may not feel any of it until around week 17 ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-13/)).

## Your body

The second trimester runs from week 13 to week 28 ([NICHD](https://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo)). Not everyone draws the line in the same place: MedlinePlus starts it at week 14 ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000557.htm)). Wherever the line sits, the description is the same. Nausea and fatigue usually ease, the abdomen expands, and you may feel movement before the trimester ends ([OWH](https://womenshealth.gov/pregnancy/youre-pregnant-now-what/stages-pregnancy)). A small bump may become visible as the uterus grows ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-13/)).

Some things are new rather than easing. Stretch marks, carpal tunnel syndrome, and darker patches on the face are common in the second trimester ([OWH](https://womenshealth.gov/pregnancy/youre-pregnant-now-what/stages-pregnancy)). Expect a prenatal visit about once a month through this trimester ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000557.htm)).

## Try today

### The second-trimester welcome

- **Time:** 10 minutes

1. Write today's date and "13 weeks" at the top of a page.
2. List three things you hope ease. The sources back two of them: nausea and fatigue usually do ([OWH](https://womenshealth.gov/pregnancy/youre-pregnant-now-what/stages-pregnancy)). The third is yours.
3. List one thing you're looking forward to. If it's movement, write the honest date next to it: perhaps not until around week 17 ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-13/)).
4. Seal it, and keep it with the week-3 scorecard.
5. Set a reminder to open it at 28 weeks, the trimester's last ([NICHD](https://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo)).

**Make it work:** Hopes aren't predictions. Writing "I hope the sickness goes" doesn't make it your fault if it lingers.

## Watch for

- **Normal:** a little puffiness in warm weather or at the end of a long day. **Call your provider** for sudden or extreme swelling, which can signal preeclampsia ([OWH](https://womenshealth.gov/pregnancy/youre-pregnant-now-what/stages-pregnancy)); extreme swelling of your hands or face is on the CDC's urgent list ([CDC](https://www.cdc.gov/hearher/maternal-warning-signs/index.html)).
- **Normal:** tiredness that's easing, but not gone ([OWH](https://womenshealth.gov/pregnancy/youre-pregnant-now-what/stages-pregnancy)). **Call your provider** for overwhelming tiredness; it is on the same urgent list ([CDC](https://www.cdc.gov/hearher/maternal-warning-signs/index.html)).
- **Normal:** round ligament pains as the uterus grows ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/2nd-trimester/week-13/)). **Call your provider right away** for moderate to severe cramping or low abdominal pain ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000557.htm)).

## For you

If nobody can tell yet, that's typical. The NHS says first pregnancies often don't show until about week 12, and later ones may show sooner ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-4/)). You can be thirteen weeks along, in your usual jeans, and entirely on schedule.

A new trimester is also a reasonable moment to ask for what you didn't ask for in the first. The NHS's week-4 list says plainly to ask for help if you're anxious or low ([NHS](https://www.nhs.uk/best-start-in-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-4/)), and that advice hasn't expired.

If you're the partner: write your own sealed note. What you hope changes for you in the next fifteen weeks is allowed to be on it.

## Sources

- NHS. "Week 13." 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-13/
- National Institute of Child Health and Human Development. "About Pregnancy." National Institutes of Health. https://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo
- MedlinePlus. "Prenatal care in your second trimester." National Library of Medicine. https://medlineplus.gov/ency/patientinstructions/000557.htm
- Office on Women's Health. "Stages of pregnancy." U.S. Department of Health and Human Services. https://womenshealth.gov/pregnancy/youre-pregnant-now-what/stages-pregnancy
- 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 4." 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/1st-trimester/week-4/