Your baby this week
From this week, length is measured from head to heel, which is why the number jumps. A creamy coating called vernix is starting to cover the skin and protect it in the amniotic fluid. Your baby is getting more active.
At 20 weeks you're halfway there. The top of your uterus is roughly level with your belly button, so from now on your provider may measure fundal height at visits; in centimeters it roughly matches the number of weeks. Your baby's length is now given from head to heel, which is why the number jumps compared with last week. Your baby swallows amniotic fluid, which helps the digestive system develop, and meconium starts collecting in the bowel. Many people feel definite movement around now. If you haven't felt anything yet, especially in a first pregnancy, that can still be normal, but mention it at your next visit.
By the numbers
Week 20 covers days 140 to 146 counted from the first day of your last period, which is 50% of a 40-week pregnancy. About 140 days remain until a 40-week due date. Since last week, an average baby gains about 2 oz (58 g). By date of conception, your baby is about 18 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
You're halfway there, and many people feel the baby move by now. A severe headache, vision changes, pain just below your ribs or sudden swelling all need a call to your provider right away.
Tests and to-dos this week
If your anatomy scan hasn't happened, make sure it's booked before 22 weeks. Start looking into childbirth and breastfeeding classes.
Quad screen (optional) · weeks 15–22 · test
Anatomy ultrasound · weeks 18–22 · test
Coming up: Glucose screening for gestational diabetes (from week 24). 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
Last week (19): Behind the buds for baby teeth, buds for permanent teeth are now forming.
Frequently asked questions
How big is the baby at 20 weeks?
About the size of a banana: about 10.2 in (26 cm) · 11.6 oz (330 g), measured head to heel. These are rounded averages, and every baby grows at their own pace.
How many months is 20 weeks pregnant?
20 weeks is in month 5 and the second trimester. About 20 weeks (140 days) remain until a 40-week due date. Months are approximate; providers count weeks and days.
How many months is 20 weeks pregnant?
Twenty weeks is in the fifth month and marks the halfway point of a 40-week pregnancy. Months are approximate; providers count in weeks and days.
What's the next test or appointment after week 20?
Next up: Glucose screening for gestational diabetes, from week 24. 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