Your baby this week
Your baby can now make fleeting facial expressions and curl the hands into fists. Muscles are getting stronger, and there's more and more movement.
At 16 weeks your baby's muscles are getting stronger, movements are more coordinated and the heart beats steadily at roughly 110 to 160 times a minute. In a first pregnancy, movements are usually felt around 18 to 20 weeks, but in later pregnancies some people notice them now: they're often described as bubbles or flutters. If you don't feel anything yet, that's completely normal. As your belly grows, lower back pain can start. Flat shoes, lifting with bent knees and sleeping on your side with a pillow can help. Your needs for iron and vitamin D increase; whether you need extra supplements depends on your lab results, so follow your provider's advice.
By the numbers
Week 16 covers days 112 to 118 counted from the first day of your last period, which is 40% of a 40-week pregnancy. About 168 days remain until a 40-week due date. Since last week, an average baby gains about 1.1 oz (30 g). By date of conception, your baby is about 14 weeks old.
Pregnancy is dated from the first day of your last period, so conception happens around week 2. Your due date is 280 days (40 weeks) from that day, and an early ultrasound may adjust it.
Your body
Some people feel the first movements between 16 and 24 weeks, often as light flutters or bubbles. If you haven't felt anything yet, that's completely normal.
Tests and to-dos this week
Your monthly checkup will likely include a blood pressure check, a urine test and listening to your baby's heartbeat. Bring any questions you've collected.
Quad screen (optional) · weeks 15–22 · test
Coming up: Anatomy ultrasound (from week 18). Full prenatal visit schedule
Tips for the second trimester
- Most healthy pregnant people are advised to get about 150 minutes of moderate activity a week, such as walking or swimming.
- Your recommended weight gain depends on your pre-pregnancy BMI, and gain usually speeds up in the second trimester.
- Once you feel your baby regularly, learn their usual pattern; a change in pattern matters more than any count.
- The flu shot is recommended at any point in pregnancy during flu season.
Call your provider or labor and delivery right away if you have:
- vaginal bleeding or leaking fluid
- regular contractions or pelvic pressure before 37 weeks
- a severe headache, vision changes, or sudden swelling of the face or hands
- a fever of 100.4 °F (38 °C) or higher, or painful urination
- after 24 weeks, your baby moving less or differently
In an emergency, call 911.
Last week and next week
Next week (17): Your baby's one-of-a-kind fingerprints are forming, and the nails keep growing.
Frequently asked questions
How big is the baby at 16 weeks?
About the size of an avocado: about 4.7 in (12 cm) · 5.1 oz (144 g), measured crown to rump. These are rounded averages, and every baby grows at their own pace.
How many months is 16 weeks pregnant?
16 weeks is in month 4 and the second trimester. About 24 weeks (168 days) remain until a 40-week due date. Months are approximate; providers count weeks and days.
When will I feel the baby move?
Usually between 16 and 24 weeks, and in a first pregnancy more often around 18 to 20 weeks or later. Early movements are easy to mistake for gas.
What's the next test or appointment after week 16?
Next up: Anatomy ultrasound, from week 18. Your provider may schedule things differently depending on your health and local practice.
Sources
- WHO Fetal Growth Charts (Kiserud et al., PLoS Med 2017)
- INTERGROWTH-21st crown-rump length standard (Papageorghiou et al., 2014)
- Hadlock et al.: In utero fetal weight standard (Radiology 1991)
- NHS: Week-by-week guide to pregnancy
- NHS: Pregnancy symptoms you need to get help for
- ACOG: How Your Fetus Grows During Pregnancy
- ACOG: Routine Tests During Pregnancy
- ACOG: Prenatal Genetic Screening Tests
- CDC: Vaccine Recommendations Before, During, and After Pregnancy
- Office on Women's Health: Prenatal care and tests
- Hungarian Decree 26/2014 (IV. 8.) EMMI on prenatal care
- NNGYK (Hungary): 2026 vaccination methodology letter
- ACOG – Group B Strep and Pregnancy (Committee Opinion 797)
- ACOG – The Rh Factor
Last reviewed: November 14, 2026 · Kitpebble editorial team
This page is for general information. It isn't medical advice or a diagnosis and doesn't replace your OB-GYN or midwife. Sizes are rounded averages. Our editorial policy