Date of delivery
Pregnancy is calculated in terms of amenorrhoea. In other words, the number of weeks since the mother's last period. In principle, a pregnancy can be expected to last 39 weeks from fertilisation until birth, or 41 weeks of amenorrhoea.
| Weeks of amenorrhoea | Weeks of pregnancy | Months of pregnancy |
|---|---|---|
6 |
4 |
1st |
10 |
8 |
2nd |
15 |
13 |
3rd |
19 |
17 |
4th |
24 |
22 |
5th |
28 |
26 |
6th |
32 |
30 |
7th |
36 |
34 |
8th |
41 |
39 |
9th |
Calculate your expected date of delivery
To calculate when your baby will be born, count 41 weeks from the date of the first day of your last period.
- Date of your last period (day 1): day/month/year = N
- Expected delivery date = N + 41 weeks = day/month/year
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