Most women of childbearing age ovulate every month. This means that one of the two ovaries releases an egg after it has matured in the ovaries. When the tiny egg, which measures approximately 0.15 cm, is released, it becomes trapped in the woman's fallopian tube and now begins a journey of an average of 5 days before it reaches the uterus. There is now a chance of pregnancy if the egg meets a spermcell within 24 hours of ovulation which succeeds in penetrating the egg and fertilizing it.

The time of ovulation

But how does the woman know when she is ovulating? It can be difficult to predict, but a rule of thumb is that ovulation occurs 14 days before the period begins. Most people have a cycle of 28 days, and if the cycle is completely accurate, then ovulation also occurred 14 days after the first day of the last period. But far from everyone has a stable cycle, and even if it is stable, it can still move if there are hormonal changes in the woman due to external or internal influences. Just the fact that you have a strong desire to get pregnant can therefore delay the cycle.

How to calculate the cycle

It's a good idea to know your cycle if you want to get pregnant. The cycle is calculated in the way that you put a cross in a calendar or note it in an app on the day you get your period. The number of days before you get your period again is the length of your cycle. The day you get your period again is then day 1 of the new cycle. If you have been keeping an eye on your cycle for a few months, you can both see if it is regular, and you can calculate an average of how long your cycle is. 

When is ovulation expected and when should I start testing? 

Use the chart here if you want to see when you are expected to ovulate or when you should start testing if you want to use the ovulation test. To see when you ovulate, you can also use the temperature method, which you can read more about here: What is the temperature method BBT and how does it work? – Gravidtid

Cycle length

Expected ovulation on this number of days following last menstrual cycles first day


Start testing with ovulation tests as many days after the first day of your last period

21

7

5

22

8

6

23

9

7

24

10

8

25

11

9

26

12

10

27

13

11

28

14

12

29

15

13

30

16

14

31

17

15

32

18

16

33

19

17

34

20

18

35

21

19

36

22

20

37

23

21

38

24

22

39

25

23

40

26

24

If you want to use ovulation tests, you can see our large selection here: Ægløsningstests – Gravidtid And if you want to follow the temperature method, you can see our selection of thermometers here: Termometre – Gravidtid