Week 13 of Pregnancy: Trimester One: Complete
Week 13 closes out the first trimester. The fog lifts for many people, the baby is about the size of a lacrosse ball, and the question you have both been circling finally comes due: who do you tell, and when. There is more nuance in that decision than the standard advice admits.
- Decide together who to tell and in what order before anyone announces anything.
- Tell parents and close family directly rather than letting them find out from a post.
- Check the notice deadline for your leave entitlement before planning the work conversation.
- Get names on an antenatal class list now, and diarise the anatomy scan window.
▸The first trimester is done
At 13 weeks pregnant the baby is around seven centimetres. Vocal cords are forming, fingerprints are developing on those newly separated fingers, and the body is starting to catch up with the head. The baby moves constantly, and still nowhere near strongly enough for her to notice.
On her side, the placenta is now doing most of the hormonal heavy lifting the early pregnancy structures were handling. This is one reason nausea commonly eases around the end of the first trimester, though timing varies and some people never get the clean handover they were promised.
Twelve weeks of secrecy, sickness and low-grade worry are behind you. Mark it somehow, even quietly. This is a genuine transition and it will slide past without ceremony if neither of you gives it one.
▸When is it actually safe to tell people?
There is no medical safety line at 12 or 13 weeks. The convention exists because the chance of miscarriage drops substantially once the first trimester is complete, and because most people have had a dating scan by then. It is a social norm built on a real pattern, not a rule handed down by clinicians.
There is a serious counter-argument worth putting on the table. If the worst had happened, the people you would most want holding you up are exactly the ones you had told nothing. Plenty of couples deliberately tell a small circle early for that reason and carry it much more lightly as a result. Neither approach is more responsible than the other, and what matters is that you decide together rather than defaulting.
▸Run the announcement instead of being run by it
Tell the people who would be hurt to hear it second-hand before anything goes public, and tell them directly. Give the grandparents their own moment rather than folding them into a group call. That five-minute phone call is one people remember for decades and costs you nothing to do properly.
Work is a separate decision with different inputs: leave paperwork, safety in her role, and whether sickness has already cost her days she has had to explain away. In many places there are deadlines for notifying an employer that unlock leave entitlements, and those differ by country, so check yours rather than assuming.
Then brace for the advice. The moment it is public, everyone from her aunt to a stranger in a queue arrives with a doctrine. Agree your policy now, including the part where you run interference so she never has to be the difficult one.
▸Book the things that book out
Antenatal and childbirth classes fill up far earlier than anyone expects, particularly the evening and weekend ones that people with jobs can actually attend. Get names on a list now. Waiting until the third trimester is how couples end up doing a rushed online course at week 36. Put the anatomy scan window in your calendar too, with a note to book leave for it.
And plan the trip. The middle of the pregnancy is generally the most comfortable stretch for travel, but that is a general pattern rather than a promise about her specifically. Check with the midwife or doctor before booking anything long-haul, look up the airline's cut-off dates, and read what your travel insurance actually says about pregnancy, because many policies say less than people assume.
▸What she is going through
- The fog is lifting for most moms.
- Announcement season is open.
▸Your missions this week
Concrete things worth doing in week 13, not just being supportive.
▸Questions dads actually ask
When is it safe to tell people you are pregnant?
There is no clinical cut-off. The 12 to 13 week convention exists because the chance of miscarriage drops substantially after the first trimester and most people have had a dating scan by then. Some couples tell a small circle much earlier so support exists if something goes wrong. Decide together rather than defaulting to the norm.
When should I tell work my partner is pregnant?
Once you know your leave entitlement and the notice deadlines, which differ by country and employer. Telling early is worth it if paperwork or planning depends on it. Agree the timing with your partner first, and tell your manager before it reaches them through office gossip.
Is it safe to travel at 13 weeks pregnant?
Many couples travel in the second trimester because it is often the most comfortable stretch, but whether it is appropriate depends on her specific pregnancy, so ask the midwife or doctor before booking. Also check the airline's pregnancy cut-off dates and read what your travel insurance covers, since pregnancy exclusions are common.
▸Sources
Checked against these pages on 17 Oct 2026. Where the guidance differs by country, follow your own midwife or doctor.
- NHS: Week 13 of the week-by-week guide
- ACOG: How your fetus grows during pregnancy
- NHS: Travelling in pregnancy
- ACOG: Travel during pregnancy
- NHS: Antenatal classes
- GOV.UK: Paternity pay and leave
▸Situations you might be hitting right now
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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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