At 17 weeks pregnant you are about 4 months along and in the second trimester, with about 23 weeks to go until your estimated due date.
At 17 weeks pregnant your baby is busy rolling, flipping and hardening its bones, and your body is catching up: a bigger appetite, heartburn, a sore back and, for some people, a bump that is suddenly obvious.
This guide covers development, size, symptoms, your belly, weight gain, tests, sleep and the warning signs that mean you should call. Every clinical detail was read in October 2026 on the sources named in the text.
Key Takeaways
17 weeks pregnant is the second trimester, about 4 months along, or 15 weeks after conception (Mayo Clinic), with about 23 weeks to go.
Nemours KidsHealth says your baby weighs almost 6 ounces (170 grams) and is about the size of a pear.
Mayo Clinic says toenails start developing and your baby is rolling and flipping, but UPMC says most people do not feel movement until around 20 weeks.
The quad screen window is weeks 15 to 22, and the anatomy ultrasound comes around 20 weeks (MedlinePlus).
Bleeding, leaking fluid, severe belly pain, a headache that will not go away or vision changes are reasons to seek care right away.
Table of Contents
17 Weeks Pregnant at a Glance
Quick Answer
At 17 weeks pregnant you are in the second trimester, about 4 months along, with about 23 weeks to go. Nemours KidsHealth says your baby weighs almost 6 ounces (170 grams) and is about the size of a pear. The anatomy ultrasound is a few weeks away, around 20 weeks (MedlinePlus).
17 weeks pregnant
What to know
Trimester
Second. UPMC (ACOG definition): 14 weeks 0 days through 27 weeks 6 days. MedlinePlus: week 14 through week 28.
Month
About 4 months, counting 4 weeks and a few days per month. Months are a convention, not a medical unit.
Weeks to go
About 23 (40 minus 17, counted from the first day of your last menstrual period).
Baby’s size
Almost 6 ounces (170 grams), about the size of a pear (Nemours KidsHealth).
Common symptoms
Increased appetite, heartburn, sore back and hips, dizziness, skin changes such as stretch marks.
This week’s care focus
Quad screen if you choose it, and booking the anatomy ultrasound.
17 weeks pregnant: quick facts with sources.
How the weeks are counted. Cleveland Clinic explains that pregnancy is dated from the first day of your last menstrual period (LMP), about two weeks before conception, which is why Mayo Clinic describes week 17 as 15 weeks after conception. If an early ultrasound changed your due date, go by the adjusted dates.
17 weeks pregnant in months. Seventeen weeks is 119 days, just about four calendar months. Cleveland Clinic uses four-week months and groups weeks 17 through 20 as month 5, so you may also see week 17 called the fifth month.
Your Baby’s Development at 17 Weeks
Source and timing
What it says is happening
Mayo Clinic, week 17 (15 weeks after conception)
Toenails start developing. The baby is becoming more active, rolling and flipping. You may feel small jerking movements from hiccups even if you cannot feel other movements yet.
Nemours KidsHealth, week 17
Bones are changing from soft cartilage to hard bone. The placenta now has thousands of tiny blood vessels that bring nutrients and oxygen, and the umbilical cord is getting thicker and stronger.
Cleveland Clinic, week 17
The skin is still thin, but the fetus will start to put on fat. A whitish coating called vernix covers the skin.
Fetal development around week 17, by source.
Where sources differ. Hearing: Cleveland Clinic says the fetus can hear you talk at week 16, while Mayo Clinic says hearing might begin at week 18. Vernix: Cleveland Clinic places it at week 17, Mayo Clinic at week 19.
How Big Is Your Baby at 17 Weeks?
Source
Week
Length
Weight
Mayo Clinic
16
About 4 3/4 inches (120 mm), crown to rump
About 4 ounces (110 g)
Nemours KidsHealth
17
Not given
Almost 6 ounces (170 g)
Mayo Clinic
18
About 5 1/2 inches (140 mm), crown to rump
About 7 ounces (200 g)
Cleveland Clinic
End of month 4 (weeks 13 to 16)
About 5 inches
About 4 ounces
Cleveland Clinic
End of month 5 (weeks 17 to 20)
About 9 to 10 inches
About 1 pound
Baby size near 17 weeks, by source.
Nemours KidsHealth compares a 17 week baby to a pear, and Cleveland Clinic compares the end of month 4 to an avocado. Mayo Clinic measures crown to rump, so legs are not counted; Cleveland Clinic does not say how it measures. Healthy babies vary.
17 Weeks Pregnant Symptoms
Symptom
What the sources say
What may help
Increased appetite
On the Nemours KidsHealth week 17 list. UPMC says you need about 340 more calories a day in the second trimester.
Nutrient-dense foods such as fruits, vegetables, whole grains, lean meats, beans and lower-fat dairy (UPMC).
Heartburn
On the Nemours KidsHealth week 17 list. UPMC says hormones relax the esophagus and the growing uterus pushes stomach acid up.
Avoid a big meal within a few hours of bedtime (MedlinePlus).
Sore back and hips
UPMC says ligaments loosen to widen the pelvis, which can make joints less stable.
Low-impact exercise such as walking or swimming (UPMC).
Leg cramps
MedlinePlus lists leg pain among the things that can wake you at night in pregnancy.
When a cramp wakes you, press your feet hard against the wall or stand on the leg (MedlinePlus).
Dizziness
Nemours KidsHealth lists dizziness due to pregnancy hormones and your growing uterus.
Mention it at your visit. Fainting is a CDC urgent warning sign.
Common symptoms at 17 weeks pregnant.
Other changes. Nemours KidsHealth also lists larger breasts (often one to two cup sizes), stretch marks, darker skin on the face or nipples, and dental problems including loose teeth. UPMC adds itchy skin as the belly stretches.
Nausea and anxiety. UPMC says some people have nausea throughout pregnancy, and to talk to your doctor if it continues or if anxiety is severe and affects your sleep or daily life.
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The 17 weeks pregnant belly. UPMC says that in the second trimester body changes become much more noticeable and you start to show. Cleveland Clinic says many people start showing signs of pregnancy in the fourth month, especially if they have been pregnant before. Some people have a clear bump at 17 weeks and others do not. Our guide to the pregnant belly by month shows the usual progression.
Feeling your baby move. UPMC says most people start to feel movement around 20 weeks, though it can start as early as 16 weeks, and that at first it may feel like a little flutter or like gas. Cleveland Clinic calls these first movements quickening. Mayo Clinic says you may notice hiccups as small jerking movements.
Weight gain. The CDC publishes total pregnancy weight gain ranges from the Institute of Medicine, based on your body mass index (BMI) before pregnancy:
Pre-pregnancy BMI
Total gain, one baby
Total gain, twins
Underweight (below 18.5)
28 to 40 lb
50 to 62 lb (from a separate study, not the Institute of Medicine)
Normal weight (18.5 to 24.9)
25 to 35 lb
37 to 54 lb
Overweight (25.0 to 29.9)
15 to 25 lb
31 to 50 lb
Obese (30.0 to 39.9)
11 to 20 lb
25 to 42 lb
Recommended total weight gain for the whole pregnancy, as published by the CDC (read October 2026).
These are totals for the full pregnancy, not targets for week 17. The CDC says to work with your health care provider on your goals.
Prenatal Care, Tests and Appointments Around Week 17
MedlinePlus says second trimester visits are monthly (UPMC: every four weeks, more often if high risk). You will be weighed, have your blood pressure checked and your abdomen measured, and your provider will make sure certain vaccinations are done (MedlinePlus).
What
Window
Details
Source
Quad screen (quadruple screen)
Between the 15th and 22nd week; most accurate at weeks 16 to 18
A blood test for the risk of conditions such as spina bifida, Down syndrome and trisomy 18. It screens; it does not diagnose.
MedlinePlus, UPMC
Amniocentesis (optional)
Between 14 and 20 weeks (MedlinePlus); between 15 and 20 weeks (UPMC)
Tests a small sample of amniotic fluid. UPMC says it is usually done only when screening or history shows higher risk, and carries a slight risk to the fetus.
MedlinePlus, UPMC
Anatomy ultrasound
Around 20 weeks
Checks organs, growth, movement, the placenta and amniotic fluid. Takes about 45 minutes and can confirm the baby’s sex.
MedlinePlus, UPMC
Glucose screening
Between weeks 24 and 28
Checks for gestational diabetes.
UPMC
Flu and COVID-19 vaccines
During respiratory virus season
Your provider can offer them.
UPMC
Tests, scans and vaccines around 17 weeks, with the window each source gives (read October 2026).
Is there a 17 week ultrasound? Not routinely. MedlinePlus says you should have an ultrasound around 20 weeks, used mainly to check the baby’s anatomy.
Vaccine guidance changes. The vaccine line reflects UPMC as read in October 2026; confirm with your provider.
What to Do This Week: A Simple Checklist
Book or confirm the anatomy ultrasound: so it lands around 20 weeks (MedlinePlus).
Decide about the quad screen: window 15 to 22 weeks (MedlinePlus).
Ask what weight gain range fits you: using the CDC ranges above.
Keep moving, gently: walking or swimming (UPMC).
Build your pillow setup now: before sleep gets harder. See the sleep section below.
Plan any trip with your provider: thinking about a getaway? Our babymoon guide covers the planning.
Save the warning signs: the list at the end of this guide, plus your provider’s after-hours number.
Sleep at 17 Weeks Pregnant
MedlinePlus lists why pregnancy sleep gets harder: a growing baby, more bathroom trips, leg and back aches, heartburn that is often worse at night, and stress or vivid dreams.
Sleep position. MedlinePlus says lying on your side with your knees bent will likely be the most comfortable position, and that many providers tell pregnant women to sleep on their left side. It adds that switching to your right side is fine if your left hip gets uncomfortable, and that it is best not to sleep flat on your back. Ask your provider what they recommend.
Pillows: MedlinePlus suggests pillows under your belly or between your legs, and a bunched-up pillow or rolled blanket at the small of your back. Our guide on how to use a pregnancy pillow walks through the setups.
A steady routine: go to bed and wake up at the same time each day, avoid exercise right before bed and cut back on caffeinated drinks (MedlinePlus).
Wind down: a 15-minute warm bath, and short daytime naps to make up for lost sleep (MedlinePlus).
Sleep aids. MedlinePlus is direct: do not take any sleep aids, including over-the-counter medicines and herbal products, and do not take any medicine without talking to your provider first. Our guide to melatonin during pregnancy covers the questions to ask.
For Partners: How to Help at 17 Weeks
Come to the anatomy scan: it takes about 45 minutes (UPMC). Decide beforehand whether to learn the sex.
Make dinner lighter and earlier: MedlinePlus says a big meal close to bedtime can make heartburn worse.
Take the heavy jobs: anything that strains a sore back.
Learn the warning signs: read the list below so you can make the call if she is unsure.
Looking Ahead: What Comes Next
Week 18: Mayo Clinic says the ears start to stand out and the baby might begin to hear sounds. See 18 weeks pregnant.
Week 19: Mayo Clinic says growth slows and the vernix coating starts to cover the baby. See 19 weeks pregnant.
Week 20: UPMC says most people feel movement around now, and MedlinePlus places the anatomy ultrasound around 20 weeks. See 20 weeks pregnant.
The CDC’s Hear Her campaign says to seek medical care immediately for any of its urgent maternal warning signs and to tell anyone treating you that you are pregnant. From the CDC, UPMC and MedlinePlus:
Vaginal bleeding or fluid leaking: the CDC lists bleeding heavier than spotting, fluid leaking, or foul-smelling discharge. MedlinePlus says to call for any bleeding.
Severe belly pain that does not go away: (CDC). MedlinePlus says to call for moderate or severe cramping or low abdominal pain, and UPMC says severe stomach pain could be preterm labor.
A headache that will not go away or gets worse: or one with vision changes, nausea or swelling of the face and hands (CDC, UPMC). These can be signs of preeclampsia.
Vision changes, dizziness or fainting, or extreme swelling of your hands or face: (CDC).
A fever of 100.4 F or higher: or chills or pain when you urinate (CDC, MedlinePlus, UPMC).
Trouble breathing, chest pain or a fast-beating heart: (CDC, UPMC).
Swelling, redness, warmth or pain in one leg or arm: which UPMC says could be a blood clot (CDC, UPMC).
Thoughts of harming yourself or your baby: (CDC, UPMC).
If you cannot reach your provider quickly, go to labor and delivery or the nearest emergency room, or call 911 for a life-threatening emergency such as severe trouble breathing, chest pain or heavy bleeding. This article is general education, not medical advice.
Frequently Asked Questions
How many months is 17 weeks pregnant?
About 4 months. Seventeen weeks is 119 days, just about four calendar months from the first day of your last period. Cleveland Clinic, which uses four-week months, groups weeks 17 through 20 as month 5. Months are only a convention, so providers count in weeks.
How big is my baby at 17 weeks?
Nemours KidsHealth says your baby weighs almost 6 ounces (170 grams) at 17 weeks and is about the size of a pear. Mayo Clinic gives about 4 3/4 inches from crown to rump at week 16 and about 5 1/2 inches at week 18. Healthy babies vary.
Is it normal not to feel the baby move at 17 weeks pregnant?
Yes, that fits what the sources describe. UPMC says most people start to feel movement around 20 weeks, though some feel it as early as 16 weeks, and that it may first feel like a flutter or gas. Ask your provider if you are worried.
Do you get an ultrasound at 17 weeks?
Not usually. MedlinePlus says you should have an ultrasound around 20 weeks, used mainly to check your baby’s anatomy, and UPMC says this anatomy scan takes about 45 minutes. Your provider may order an earlier scan for a specific reason.
How much weight should I gain during pregnancy?
The CDC publishes Institute of Medicine ranges by pre-pregnancy BMI for the whole pregnancy: 28 to 40 pounds if underweight, 25 to 35 pounds at a normal weight, 15 to 25 pounds if overweight and 11 to 20 pounds with obesity, for one baby. The CDC says to set your goals with your provider.
What position should I sleep in at 17 weeks pregnant?
MedlinePlus says lying on your side with your knees bent will likely be most comfortable, and that many providers tell pregnant women to sleep on their left side. It says it is best not to sleep flat on your back. Pillows under your belly or between your legs can help.
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