Pregnancy Calendar
Pregnancy is counted from the first day of the last period and lasts around 40 weeks. The 6th week of pregnancy is also written as 5+0 to 5+6, meaning 5 completed weeks and 0 to 6 days. It is counted in 10 months of 4 weeks each and in 3 trimesters.
4th weekImplantationThe size of a fine grain of sand
5th weekThe missed periodThe size of a poppy seed
6th weekThe heart starts to beatThe size of a sesame seed
7th weekArms and legs start to growThe size of a lentil
8th weekThe fingers take shapeThe size of a raspberry
9th weekThe heart beats at its fastestThe size of a cherry
10th weekFingers and toes separateThe size of a walnut
11th weekThe embryo becomes a fetusThe size of a plum
12th weekThe first third is behind youThe size of a limeWeeks of pregnancy, months, and trimesters
| Week of pregnancy | Weeks and days | Month | Trimester |
|---|---|---|---|
| 1st week | 0+0 to 0+6 | 1st | 1st |
| 2nd week | 1+0 to 1+6 | 1st | 1st |
| 3rd week | 2+0 to 2+6 | 1st | 1st |
| 4th week | 3+0 to 3+6 | 1st | 1st |
| 5th week | 4+0 to 4+6 | 2nd | 1st |
| 6th week | 5+0 to 5+6 | 2nd | 1st |
| 7th week | 6+0 to 6+6 | 2nd | 1st |
| 8th week | 7+0 to 7+6 | 2nd | 1st |
| 9th week | 8+0 to 8+6 | 3rd | 1st |
| 10th week | 9+0 to 9+6 | 3rd | 1st |
| 11th week | 10+0 to 10+6 | 3rd | 1st |
| 12th week | 11+0 to 11+6 | 3rd | 1st |
| 13th week | 12+0 to 12+6 | 4th | 2nd |
| 14th week | 13+0 to 13+6 | 4th | 2nd |
| 15th week | 14+0 to 14+6 | 4th | 2nd |
| 16th week | 15+0 to 15+6 | 4th | 2nd |
| 17th week | 16+0 to 16+6 | 5th | 2nd |
| 18th week | 17+0 to 17+6 | 5th | 2nd |
| 19th week | 18+0 to 18+6 | 5th | 2nd |
| 20th week | 19+0 to 19+6 | 5th | 2nd |
| 21st week | 20+0 to 20+6 | 6th | 2nd |
| 22nd week | 21+0 to 21+6 | 6th | 2nd |
| 23rd week | 22+0 to 22+6 | 6th | 2nd |
| 24th week | 23+0 to 23+6 | 6th | 2nd |
| 25th week | 24+0 to 24+6 | 7th | 2nd |
| 26th week | 25+0 to 25+6 | 7th | 2nd |
| 27th week | 26+0 to 26+6 | 7th | 2nd |
| 28th week | 27+0 to 27+6 | 7th | 2nd |
| 29th week | 28+0 to 28+6 | 8th | 3rd |
| 30th week | 29+0 to 29+6 | 8th | 3rd |
| 31st week | 30+0 to 30+6 | 8th | 3rd |
| 32nd week | 31+0 to 31+6 | 8th | 3rd |
| 33rd week | 32+0 to 32+6 | 9th | 3rd |
| 34th week | 33+0 to 33+6 | 9th | 3rd |
| 35th week | 34+0 to 34+6 | 9th | 3rd |
| 36th week | 35+0 to 35+6 | 9th | 3rd |
| 37th week | 36+0 to 36+6 | 10th | 3rd |
| 38th week | 37+0 to 37+6 | 10th | 3rd |
| 39th week | 38+0 to 38+6 | 10th | 3rd |
| 40th week | 39+0 to 39+6 | 10th | 3rd |
| 41st week | 40+0 to 40+6 | 10th (after the due date) | 3rd |
| 42nd week | 41+0 to 41+6 | 10th (after the due date) | 3rd |
How weeks are counted
- Week of pregnancy: counted from the first day of the last period, not from conception. With a 28-day cycle, ovulation is at around 2+0.
- 4+3 means 4 completed weeks and 3 days. That is the 5th week of pregnancy.
- Months: 10 months of 4 weeks each. The calculated due date is 40+0, the end of the 10th month.
- Trimesters: the 1st up to the 12th week of pregnancy, the 2nd from the 13th to the 28th week, the 3rd from the 29th week.
The Due Date Calculator shows your current week and your due date.
Frequently asked questions
Which week of pregnancy is which month?
Weeks 1 to 4 of pregnancy are the 1st month, weeks 5 to 8 the 2nd month, and so on. The 10th month covers weeks 37 to 40.
What does 4+3 weeks mean?
4 completed weeks and 3 days since the first day of the last period. That is the 5th week of pregnancy.
When does the 2nd trimester start?
With the 13th week of pregnancy, that is, at 12+0. The 3rd trimester begins with the 29th week of pregnancy.
Why is pregnancy counted from the period and not from conception?
The first day of the last period is usually known, but the day of conception is not. That is why, by calculation, the pregnancy is already 2 weeks old at conception.