16 Weeks Pregnant: Symptoms, Baby Development and What to Expect

At 16 weeks pregnant you are about 4 months along, in the second trimester, with about 24 weeks to go until your estimated due date.

At 16 weeks pregnant your baby is about the size of an avocado, according to Nemours KidsHealth, and many people are starting to feel more like themselves. You might be watching for a bump, wondering whether that flutter was gas or your baby, and deciding about second trimester screening.

This guide covers development, size, symptoms, your belly, tests, sleep and the warning signs that mean you should call. Every clinical detail was read in October 2026 on the primary sources named in the text.

16 Weeks Pregnant at a Glance

How the weeks are counted. Mayo Clinic explains that your due date is set 40 weeks from the start of your last period, so you are not actually pregnant for the first week or two of that count. That is why Mayo Clinic calls week 16 “14 weeks after conception.” Cleveland Clinic says an ultrasound, usually at the first prenatal visit, confirms the due date and may shift it, usually by only a few days. If your dates were adjusted, go by the new ones.

Which trimester? Sources draw the lines differently, but week 16 is second trimester on all of them:

Your Baby’s Development at 16 Weeks

These sources describe what is typical around now, not what your own baby is doing on a given day.

Boy or girl? Mayo Clinic says the baby’s sex likely becomes clearer around week 14, but Cleveland Clinic says the sex is often visible on the second trimester anatomy ultrasound, often around 20 weeks. Finding out is optional, so decide ahead of time whether you want to know.

How Big Is Your Baby at 16 Weeks?

Each figure is printed as the source reports it, with nearby weeks for context.

Why the numbers differ. Mayo Clinic measures crown to rump, from the top of the head to the bottom of the tailbone, so the legs are left out. The Office on Women’s Health and KidsHealth do not say how they measure. Treat all of these as rough averages.

16 Weeks Pregnant Symptoms

KidsHealth says nausea and morning sickness may have eased by now, though you will likely still have other symptoms. These are the ones primary sources tie to this stage.

Cleveland Clinic also lists hemorrhoids, varicose veins, mild swelling and a higher chance of urinary tract and yeast infections.

Your Body and Belly at 16 Weeks

Is there a 16 weeks pregnant belly yet? Maybe. KidsHealth says your belly is growing and you might start to look pregnant at week 16. But Cleveland Clinic says not to worry if you do not have a bump right away: it takes time, and no two pregnancies look the same. Our pregnant belly by month guide shows the range.

Skin changes. The Office on Women’s Health lists darker skin around the nipples, a line from the belly button to the pubic hairline, darker patches on the face, stretch marks, and itching on the belly, palms and soles.

Feeling your baby move. Cleveland Clinic says quickening, the first movement you can feel, happens around 16 to 20 weeks. If you have been pregnant before, you may notice it by about 16 weeks; in a first pregnancy it is common not to feel movement until 20 weeks. UPMC says it may feel like a little flutter, like gas, or like air bubbles bursting. An anterior placenta (at the front of the uterus) can make it harder to feel (Cleveland Clinic).

Prenatal Care, Tests and Appointments Around Week 16

Cleveland Clinic says prenatal visits in the second trimester usually happen every four weeks, unless your pregnancy is high risk or your provider advises otherwise. Several tests have windows that include week 16:

Screening is not diagnosis. KidsHealth says an abnormal second trimester screening result does not necessarily mean your baby has a problem. These tests are offered, and choosing them is up to you; your provider can explain what each one can and cannot tell you.

A 16 week ultrasound? The detailed anatomy scan comes around 20 weeks. If you do have a scan now, Mayo Clinic says limb movements can be seen at this stage.

What to Do This Week: A Simple Checklist

• Keep taking your prenatal vitamin, as Cleveland Clinic advises for the second trimester. Our guide to prenatal vitamins explains what to look for.
• Decide whether you want second trimester screening while the window is open.
• Move most days: Cleveland Clinic suggests about 20 minutes a day, such as walking or swimming, and avoiding contact sports and activities where you could fall.
• Review food safety. Cleveland Clinic says to avoid raw or undercooked meat, unpasteurized dairy, deli meats and fish high in mercury.
• Skip hot tubs and saunas, hand off the litter box, and avoid smoking, alcohol and recreational drugs (Cleveland Clinic).
• Add about 340 extra calories a day of nourishing food (UPMC).

A small tip: write down the date you first think you feel movement, even if you are not sure. It helps when your provider asks.

Sleep at 16 Weeks Pregnant

Easing nausea can make nights easier, but a stuffy nose or backache can still interrupt sleep.

Sleep position. Cleveland Clinic advises sleeping on your side instead of your back in the second trimester, for circulation, and says not to worry if you wake up on your back: your body will usually prompt you to move. KidsHealth says many people find side sleeping with knees bent more restful, and that a full body pillow helps.

• Set up your pillows now: before your bump grows. Our guide on how to use a pregnancy pillow walks through the options.
• Ease a stuffy nose: congestion is common in the second trimester (Cleveland Clinic). Ask your provider before using any medicated spray.
• Ask before any sleep aid: check with your provider before taking any sleep medicine or supplement. Read can you take melatonin while pregnant first.

For Partners: How to Help at 16 Weeks

• Go to the next prenatal visit if you can, and talk through the screening decision together, knowing the final call belongs to the pregnant person.
• Plan something restful together. If you are thinking about a trip, our babymoon guide covers timing and what to ask your provider first.
• Learn the warning signs at the end of this guide so you can help make the call.

Looking Ahead: What Comes Next

• Week 17: toenails start developing and your baby rolls and flips more (Mayo Clinic). See 17 weeks pregnant.
• Week 18: your baby might begin to hear sounds (Mayo Clinic). See 18 weeks pregnant.
• Week 19: many people feel the first movements somewhere in this window. See 19 weeks pregnant.
• Week 20: the halfway point and the usual time for the anatomy scan (UPMC). See 20 weeks pregnant.

Looking back? Our 14 weeks pregnant guide covers the start of the second trimester.

Related Betteroo Guides

• 15 Weeks Pregnant
• 17 Weeks Pregnant
• 18 Weeks Pregnant
• Pregnant Belly by Month
• Prenatal Vitamins Guide
• How to Use a Pregnancy Pillow

When to Call Your Provider

Seek medical care right away. The CDC’s Hear Her campaign lists these urgent maternal warning signs and says to seek medical care immediately if you have any of them:

• A headache that won’t go away or gets worse over time.
• Dizziness or fainting.
• Changes in your vision.
• A fever of 100.4 F or higher.
• Extreme swelling of your hands or face.
• Thoughts about harming yourself or your baby.
• Trouble breathing, chest pain or a fast-beating heart.
• Severe nausea and throwing up.
• Severe belly pain that doesn’t go away.
• Vaginal bleeding or fluid leaking during pregnancy.
• Severe swelling, redness or pain in your leg or arm.
• Overwhelming tiredness.

Also call your provider for these, which UPMC and Cleveland Clinic list for the second trimester:

• Unusual or severe cramping or abdominal pain (Cleveland Clinic). UPMC notes that strong cramping could be preterm labor.
• Regular contractions, more than four in an hour (Cleveland Clinic).
• Any fluid leaking from the vagina (Cleveland Clinic).
• Pain when you urinate, which can be a sign of a urinary tract infection (UPMC).

Movement. At 16 weeks, not feeling movement is common. Cleveland Clinic says you should generally feel some movement by 20 to 24 weeks, and to talk with your provider if you have not by then.

If you are unsure whether something is serious, call anyway, and say how many weeks pregnant you are. For a medical emergency, such as heavy bleeding, severe trouble breathing, chest pain or a seizure, call 911. This article is general education, not medical advice.

Frequently Asked Questions