Week 16
Your baby is the size of an avocado
Your body just started making your baby's first meal. Colostrum, the thick yellowish premilk packed with antibodies, can begin production as early as this week. You probably won't see any sign of it for months. But the preparation is underway. Meanwhile, your baby is avocado-sized, grabbing at the umbilical cord for entertainment, and their ears are moving into position to start picking up sound. Week 16 is quiet on the outside. Underneath, a lot is happening.
Key takeaways
- Colostrum production can start as early as week 16, even though most people won't notice visible signs until the third trimester.
- Your baby's ears are nearing their final position on the head. Consistent fetal auditory responses to external sound aren't reliable until later in pregnancy.
- Some experienced parents feel their first flutters of movement around now, though most first-timers won't feel anything until closer to weeks 18-22.
- Your heart is pumping roughly 50% more blood than before pregnancy, with most of that increase already in place by this point.
Your baby grabs the umbilical cord for fun now
Your baby measures more than 4 inches from crown to rump and weighs over 3 ounces. Avocado-sized. The one everyone remembers.
Limb movements are getting coordinated. Your baby can flex arms and legs, make fists, and grab the umbilical cord like a toy. On ultrasound, it looks like deliberate play.
These movements are purposeful now, not just reflexes.
Here's a cool detail. Eyes are still fused shut, but your baby can sense changes in light through the eyelids. Shine a flashlight on your belly and your baby might actually turn away from it.
Your baby's ears are close to their final position. The ears are nearing their final position on the head. The inner ear is still maturing, and consistent fetal auditory responses to external sound aren't reliable until around 28 weeks.
The face looks unmistakably human now. A profile with a nose, chin, and forehead. If you got an ultrasound this week, you might be surprised how much has changed since the first trimester.
Skin is thickening. Still see-through, but less so every day. The musculoskeletal system is strengthening, and your baby's proportions are evening out. Starting to look like a tiny person you'd recognize.
Is that flutter in your belly gas or your baby?
Nobody can tell you yet. Not even your provider.
Quickening is the first time you feel your baby move, and it becomes possible around now. But most people don't feel it this early. A 2022 study of over 2,000 women found the average onset of perceived movement was 19 weeks. Experienced parents felt it about a week sooner.
The sensation is usually described as bubbles, popcorn popping, or a light tapping. Nothing dramatic. It comes and goes, and you'll probably second-guess it the first few times.
What delays perception: an anterior placenta cushions the kicks, higher BMI absorbs them, and first pregnancies mean you don't yet know the sensation.
None of this is a problem.
Your body is doing serious invisible work right now. Your cardiac output has increased roughly 50% above pre-pregnancy levels by this point. That's why stairs feel harder and your heart sometimes races.
Stay hydrated. Stand up slowly if you're getting dizzy.
Your center of gravity is shifting as your uterus grows. Flat shoes help. Your bump is growing enough that skin may start feeling tight or itchy. Keep it moisturized.
And something most people don't expect this early: your breasts can begin making colostrum as early as week 16. This thick, antibody-rich premilk won't be visible for months, if at all before delivery.
But production is underway.
For dads
Here's your move:
Open a baby registry this week. Not a mental note. Actually sit down together, pick a platform, and start adding things. Here's the move that matters: before that conversation, spend 30 minutes researching one big-ticket category on your own. Car seats, strollers, cribs. Read the reviews. Narrow it to two or three options. Then bring those to the table. Taking the research load off your partner for even one category is a concrete way to show you're in this. The second trimester is when most couples start the registry, and getting ahead of it means you're not scrambling at 34 weeks when shower invites go out.
Real talk:
The money part hits different once you start looking at gear. You'll click through car seats and strollers and suddenly the financial reality of a baby gets very real. Some anxiety here is normal. Don't spiral and don't keep it to yourself. Talk to your partner about a budget that works, not one that looks good on paper. You don't need the top-rated everything. You need the basics done well. And here's the reframe: the most expensive choices are the ones you make in a panic because you waited too long. Planning early is the cheapest thing you can do.
Common concerns
I'm 16 weeks and haven't felt any movement. Is that normal?+
Completely normal. A study of over 2,000 women found the average onset of perceived movement was 19 weeks. First-time parents often don't feel anything until weeks 18 to 22. Factors like placenta position and body type affect timing too. If your provider isn't concerned, there's no reason for you to be.
When should I start a baby registry?+
The second trimester is the sweet spot. You're feeling better, you have time to research, and if anyone throws a shower, they'll want the registry ready by the third trimester. Start now and add to it over the coming weeks. Don't try to finish it in one sitting.
Should I start talking to my baby now that they can hear?+
The ears are nearing their final position, but consistent auditory responses to external sound aren't reliable until later in pregnancy. That said, talk, read, and play music if it feels right. Your baby already hears your heartbeat and digestive sounds through vibration. There's no pressure to make this a structured activity.
I keep getting dizzy when I stand up. Should I worry?+
Occasional dizziness when changing positions is common in the second trimester. Your blood volume has expanded and your blood vessels are more relaxed, which can cause temporary blood pressure drops. Stay hydrated, stand up slowly, and eat regular small meals. Contact your provider if dizziness is frequent, severe, or comes with fainting or vision changes.
Product picks for week 16
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Skechers Women's Go Walk Joy Slip-On
Lightweight slip-on walking shoe with cushioned insole for the balance and stability the content recommends
Momcozy U-Shaped Pregnancy Pillow
Full-body maternity pillow for back, belly, and hip support as your center of gravity shifts
Earth Mama Belly Oil
Calendula-infused oil for pregnancy skin that's starting to feel tight and itchy as the belly grows
Sources
- ACOG, How Your Fetus Grows During Pregnancy (2024) — https://www.acog.org/womens-health/faqs/how-your-fetus-grows-during-pregnancy
- Mayo Clinic, Fetal Development: The 2nd Trimester (2025) — https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20046151
- Tveit JVH et al., Maternal perception of fetal movements: onset and associated factors, Journal of Perinatal Medicine (2022) — https://pubmed.ncbi.nlm.nih.gov/35779269/
- Cleveland Clinic, Colostrum: What Is It, Benefits & What To Expect (2024) — https://my.clevelandclinic.org/health/body/22434-colostrum
- Sanghavi M & Rutherford JD, Cardiovascular Physiology of Pregnancy, Circulation (2014) — https://www.ahajournals.org/doi/10.1161/circulationaha.114.009029
A quick note: This content is for informational purposes only and is not a substitute for professional medical advice. Always talk to your healthcare provider about any questions or concerns. Content based on guidance from the American College of Obstetricians and Gynecologists (ACOG), the American Academy of Pediatrics (AAP), Mayo Clinic, and peer-reviewed medical literature. Learn how we create our content.