The brain myelination continues. The lungs are making their very last adjustments. The fat that has been depositing since week 26 is fully present — the soft roundedness of a newborn, completely assembled. The baby at 40 weeks is 3.4kg and 360mm, and the placenta — that extraordinary organ that has sustained this entire pregnancy — is making its final contribution.
These maternal antibodies will protect your baby through the first months of life while their own immune system builds its independent responses. They are not a permanent shield — they wane over the first six months — but they are precisely calibrated to the environmental threats the baby is most likely to encounter, because they come from the immune system of the person they are about to be born to. It is the most intimate possible form of protection: a lifetime of immunity, given in nine months.
The placenta that began as a cluster of cells at week 8 — that grew alongside the baby, that oxygenated and nourished and protected for forty weeks — makes this final transfer, and then its work is done. It is one of the most remarkable organs in biology. It exists only for this pregnancy, only for this baby, and it gives everything it has.
I learned about the placenta's final antibody transfer at my fortieth week appointment and I couldn't stop thinking about it. Forty weeks of work, ending with this final gift. I asked to see my placenta after the birth and the midwife showed it to me. It was extraordinary — dark and veined and entirely purposeful. I held it for a moment and thought: this kept them alive. Nothing I make will ever be this important. And then they put my baby on my chest and I understood that I was wrong — because the baby was more important still. But the placenta came very close.
The due date is a statistical midpoint, calculated as 280 days from the first day of the last menstrual period. It is the date by which approximately 50% of spontaneous labours will have begun. It is not a deadline. It is not the last safe day. It is a number on a calendar that, for 96% of pregnancies, does not coincide with the actual birth date — and that is entirely normal.
At 40 weeks: a membrane sweep is offered if not yet performed. You may be offered another appointment in 2–3 days.
At 41 weeks: an ultrasound scan to check the amniotic fluid level and baby's wellbeing; more frequent monitoring; induction is offered and the conversation begins in earnest.
At 42 weeks: induction is strongly recommended. The risks of continuing beyond this point (placental function declining, amniotic fluid reducing, increased risk of stillbirth) outweigh the risks of induction. This is not a failure of the pregnancy — it is the natural variation of gestation meeting its practical outer limit.
See the Labour & Birth guide and the Scans & Antenatal Care guide for the full induction pathway and what each stage involves.
Do not take unproven herbal or physical interventions without midwife guidance. Castor oil and some herbal supplements carry real risks. Evening primrose oil has limited and inconsistent evidence. Long walks and spicy food cause no harm but have no established effect on labour onset. The body will begin when it is ready. Your role is to rest, be patient, and remain attentive.
You have reached week 40 of the WiseMama pregnancy guide. Whatever is happening on the day you read this page — whether you are in early labour, anxiously waiting, or have already given birth and are reading back through what the guide said — this is the end of the pregnancy story as this guide tells it.
What the guide has tried to do, from week 4 to week 40, is tell the story of what was happening inside — not just the clinical facts, but the specific wonders: the fingerprints forming under amniotic pressure, the first dreams, the eyes opening after eighteen weeks sealed, the skull built to flex through the birth canal, the placenta making its final gift. Every week has had its own detail, its own particular thing worth knowing, its own place in the arc of the most extraordinary biological process in human experience.
I read the WiseMama guide from week four. Every Sunday morning I would read the next week. By week forty I had this whole record of what had been happening while I hadn't been able to see it — what the baby was doing, what was forming, what was being prepared. When they finally put her on my chest, I felt like I already knew her in a way I couldn't explain. I did know her. We'd been building this knowledge together for nine months. The guide was part of that. I'm glad it existed.
The pregnancy ends. The baby arrives. A different kind of knowledge begins — the knowledge of a specific face, a specific cry, a specific person who has been practising for this moment for forty weeks. The WiseMama app continues with you through the first year of your baby's life: weekly development updates, the postnatal topics, and the community. But that is the next guide's story. This one is done.
28 topic guides, free, always. The birth guides and the postnatal guides — all of them available whenever you need them.
The due date. You have both carried this pregnancy to its full term. The preparation that began with a positive test — perhaps months before, perhaps with a longer journey than that — arrives here, at week forty, ready. The work you have done as a partner across these months: showing up, supporting, reading, preparing, attending appointments, building knowledge, reducing burdens, being present. That work has mattered. It continues to matter, in a different form, from the moment the baby arrives.
The birth, when it begins, will be the most significant thing either of you has done together. Your role in it is specific and important — not passive observer but active, informed, present support. The Labour & Birth guide's partner section tells you exactly what to do. Read it one more time today.
- Be completely available, now. Phone on, close to home, no commitments that can't be interrupted. The birth begins without appointment.
- Know what to say when it begins. Not "are you sure?" Not "should we time them?" But: calm, present, practical, warm. You have prepared for this. Trust it.
- After the birth: skin-to-skin matters for partners too. Ask for it. Hold your baby. Be present for the first hour — not on the phone, not managing the announcement, not thinking about what comes next. Be in the room.
- The first weeks are where you are most needed. The Fourth Trimester guide describes what is coming with honesty. Read it again this week, and then meet it with everything you have.
Trust yourself. You have done everything that could be done. You have read, prepared, attended, asked, planned, packed, and waited. The knowledge you have built across forty weeks of pregnancy — about how a baby develops, about what labour involves, about what the first weeks require — is real and it is yours. When the moment comes, that knowledge will be there.