Week 16 of Pregnancy: Growth Spurt Incoming
Week 16 is the tennis-ball week, with a growth spurt right behind it. It is also roughly when the hearing machinery starts coming online, which is why talking to the bump stops being a gimmick and becomes a habit worth building. Two jobs: start using your voice, and lock down your paternity leave.
- Read your actual paternity leave policy this week, then get the plan confirmed in writing.
- Start talking to the bump and attach it to an existing routine so it sticks.
- Begin the weekly bump photo, same spot and framing, and ask her first every time.
- Agree a bump-touching policy together so she is not enforcing it alone.
▸Tennis ball now, growth spurt next
At 16 weeks pregnant the baby is around 11 to 12 cm and roughly 100 grams. A tennis ball. Week 16 sits right at the front of a significant growth push, so the numbers will climb noticeably over the next month, and the bump will follow them.
The head sits more upright on the neck now, and the facial muscles work, so the baby can squint and frown. Limbs are properly proportioned and moving in coordinated patterns rather than jerks. Almost none of that registers for her yet.
▸The baby can start to hear you
The structures of the ear and the nerve pathways feeding the brain develop across the second trimester, and the fetus begins responding to sound during this stretch. That is the well-established version, and it is enough. Be careful with the stronger claims about babies learning one specific voice; the evidence there is less settled than the confident phrasing suggests.
What you can lean on: lower-pitched sound carries through tissue better than higher-pitched sound. Your voice is well suited to the job. That is why a talk-to-the-bump mission starts appearing from week 16 and keeps appearing.
How to do it without feeling ridiculous: bolt it onto something you already do. Read a page of whatever you are reading out loud while she is on the sofa. Give the day a two-minute rundown before bed. The content does not matter. What matters is that it becomes automatic, because the version of this habit worth having is the one still running at week 39.
▸Lock in paternity leave, in writing
The biggest mission this week is administrative, which is exactly why men put it off. Entitlements vary enormously by country and by employer, and the gap between what you assume you get and what you actually get is often measured in weeks of pay.
Do it in this order. Read the actual policy document, not what a colleague told you. Find out how much is paid and at what rate. Check the notice period, because some schemes require formal notice months ahead and quietly penalise late requests. Then talk to your manager and get the agreed plan confirmed in writing.
Then plan the shape of it, not just the length. Taking it all at once around the birth is one option. Holding some back for when she returns to work is another. Decide it with her, because your leave pattern shapes her plans as much as yours.
▸The bump goes public
Somewhere around now the bump stops being ambiguous, and the social situation changes. Colleagues notice, strangers comment, and some people reach out and touch her without asking. Agree in advance who is allowed near the bump and how you intercept, so she is not the one saying no every single time.
Start the weekly bump photo now. Same wall, same time of day, same rough framing. It takes eleven seconds and in five months it is the only visual record of this you will have. Ask before every one; some weeks she will not want a camera near her, and that answer is final.
▸What she is going through
- The bump is becoming real.
- She may feel first flutters soon.
▸Your missions this week
Concrete things worth doing in week 16, not just being supportive.
▸Questions dads actually ask
Can the baby hear my voice at 16 weeks?
The hearing system is developing through this part of pregnancy and the fetus begins responding to sound during the second trimester. Whether it can distinguish your voice specifically at 16 weeks is not something anyone can state with confidence. Talk anyway. It costs nothing, lower-pitched voices carry through reasonably well, and it builds the habit.
How big is the baby at 16 weeks pregnant?
Roughly a tennis ball: around 11 to 12 cm and about 100 grams, with plenty of normal variation. Week 16 sits at the start of a growth spurt, so expect those numbers to move quickly. Growth is tracked by her care team at scans, and a single measurement in isolation tells you very little.
When should I tell my employer about paternity leave?
Earlier than feels necessary. Many schemes carry formal notice requirements and some enforce them strictly, and the rules differ by country and employer. Read your own policy this week instead of relying on what a colleague remembers, confirm what is actually paid, then get the agreed dates in writing once you have spoken to your manager.
▸Sources
Checked against these pages on 17 Oct 2026. Where the guidance differs by country, follow your own midwife or doctor.
- NHS: Week 16 of the week-by-week guide
- ACOG: How your fetus grows during pregnancy
- GOV.UK: Paternity pay and leave
- US Department of Labor: Family and Medical Leave Act
▸Situations you might be hitting right now
Pregnant and reading this? Send it to him
One tap sends him week 16 of pregnancy, written for the dad: what is happening, what you are going through, and his jobs this week.
This is general information for expectant fathers, not clinical guidance. Anything about symptoms, pain, or bleeding goes to your midwife, doctor, or emergency service, not to an app.
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