16 Weeks Pregnant
Reviewed by Safi Allah Khan
Medically reviewed by: Safi Allah Khan · Written by the Momi team · Last updated 20 October 2026
Quick answer: At 16 weeks pregnant, your baby is about the size of an avocado, about 11.6 cm (4.6 in) long. You're in the second trimester, in month 4, with 24 weeks to go until your due date. This week's milestone: first movements possible. Symptoms vary from person to person.
| Week 16 at a glance | |
|---|---|
| Trimester | Second |
| Month | 4 |
| Weeks to due date | 24 |
| Baby's size | About the size of an avocado |
| Length | About 11.6 cm (4.6 in) |
| Weight | About 100 g (3.5 oz) |
| This week | First movements possible |
Sizes are typical averages. Before about 20 weeks, length is measured crown to rump; after that, head to heel.
Your baby at 16 weeks
Your baby is about the size of an avocado and weighs about 100 g (3.5 oz). ACOG says the fetus is more than 4 inches long by the end of week 16. Hearing is beginning to develop.
Your body at 16 weeks pregnant
Some people feel the first flutters this week, especially if they have been pregnant before. The NHS says first movements are usually felt between 16 and 24 weeks.
Things to do this week
- Attend your 16-week check if you are in the UK.
- Rest on your side if lying on your back feels uncomfortable.
- Note the first time you think you feel movement.
When to call your doctor or midwife
Contact your care team straight away if:
- you have bleeding or fluid leaking from your vagina
- you have severe belly pain that doesn't go away
- you have a fever of 100.4°F (38°C) or higher
- you have a headache that won't go away or gets worse
- you have regular, painful tightenings
If something feels wrong, trust that feeling and call. In an emergency, call your local emergency number.
Track week 16 in Momi
Record your first flutter in your Momi diary. You may be asked about it later. Momi follows your pregnancy week by week with your baby's size and development, and keeps your diary, bump photos, appointments, kick counts and contractions in one place.
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Keep reading
← 15 weeks pregnant · All weeks · 17 weeks pregnant →
Sources
- ACOG: Changes During Pregnancy (infographic)
- NHS: Your baby's movements
- NHS: Antenatal care and appointments
- CDC: Urgent Maternal Warning Signs
Medical disclaimer: Momi and this website provide general information, not medical advice. Always talk to your doctor or midwife; in an emergency call your local emergency number.
FAQ
How big is a baby at 16 weeks pregnant?
On average, a baby at 16 weeks is about the size of an avocado: about 11.6 cm (4.6 in), about 100 g (3.5 oz). These are typical averages, and healthy babies vary.
How many months is 16 weeks pregnant?
16 weeks pregnant is in the fourth month of pregnancy and the second trimester. Months don't divide evenly into 40 weeks, so different sources may label the month slightly differently.
What should I do at 16 weeks pregnant?
Attend your 16-week check if you are in the UK. Rest on your side if lying on your back feels uncomfortable.
Related guides
Track this in Momi
Momi is a free pregnancy tracker app for iPhone and Android that follows pregnancy week by week, estimates the due date, and keeps a pregnancy journal, weight log, kick counter and contraction timer in one place.
