An estimate for a healthy single pregnancy going into labour on its own, based on studies of spontaneous labour timing. Only about 4% of babies arrive on the due date itself. Doctors usually offer induction around 41 weeks, so few pregnancies reach 42 weeks.
| Gestation | Date | Chance labour has started by then |
|---|---|---|
| 37 weeks | Tue, 29 Sep 2026 | 9% |
| 38 weeks | Tue, 6 Oct 2026 | 16% |
| 39 weeks | Tue, 13 Oct 2026 | 29% |
| 40 weeks (due date) | Tue, 20 Oct 2026 | 47% |
| 41 weeks | Tue, 27 Oct 2026 | 71% |
| 42 weeks | Tue, 3 Nov 2026 | 91% |
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Only about 4% of babies arrive on their due date. Most come within 10 days either side, and first babies tend to arrive a few days later than later ones.
Enter your due date to see the chance that labour starts today (if it hasn't already), in the next 7 days, and by each week from 37 to 42, based on studies of when spontaneous labour begins.
| Due Date | 20 Oct 2026 |
| First baby? | Yes — first baby |
| Chance labour starts today | 4.1% (if it hasn't started yet) |
| Chance it starts within the next 7 days | 40% |
| Today you are | 39 weeks 6 days |
| Chance of labour by your due date | 47% |
| Half of babies like yours have arrived by | Thu, 22 Oct 2026 (first babies tend to come a few days late) |
| Most labours start between | Sat, 10 Oct 2026 and Fri, 30 Oct 2026 (about 59%) |
47%.
Try this example →About 4%.
On average a few days later than later babies; about half of first babies arrive by 40 weeks + 2 days.
Most hospitals offer induction between 41 and 42 weeks, earlier if there is a medical reason.