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 small egg, which measures approximately 0.15 cm is released, it is trapped in the woman's fallopian tube, and now a journey of an average of 5 days begins before it reaches the uterus.The chance for pregnancy is present, if the egg within 24 hours after ovulation, encounters a spermcell that succeeds in penetrating the egg and fertilizing it. 

The body is ready

Already a few days before ovulation, your mucousmembrane has become thicker and more blood-filled. This means that a possibly fertilized egg more easily can attach and develop into a pregnancy. If, on the other hand, the egg has not been fertilized, your thick mucous membrane will instead be rejected along with the unfertilized egg and approximately 14 days after ovulation, you will have your period, which lasts for approximately 5 days. After this, a new mucous membrane grows in the uterus, and the process of ovulation starts all over again. This is called a cycle and it lasts an average of 28 days. However, it can be both shorter and longer, as the cycle is controlled by hormones that are produced in several places in the brain and in the ovaries. This means that both physical and mental changes can affect your cycle as well as its length 

When is the chance of pregnancy greatest?

There are many rules of thumb here, but research shows that sperm normally live in the uterus and fallopian tubes for 2-3 days, but can live there for up to 7 days. This means that even if you have intercourse up to 7 days before the release of the egg, a sperm cell can fertilize the egg. However, some of the sperm can perish during the days, and therefore research indicates that the chance of pregnancy is greatest if you have sexual intercourse 1-2 days before ovulation and up to 24 hours after ovulation. If you have sex 2-3 times a week, then you can almost be sure to match the ovulation and hope for the sperm to fertilize the egg. 

How do you know a woman is ovulating?

There are various physical symptoms of ovulation, which can be read more about here: What are the symptoms of ovulation? – Gravidtid If you want to know exactly when - or if - you have ovulation, then you need an ovulation test: Ægløsningstests – Gravidtid It measures the hormone level Lutropin also called LH. Sundhed.dk recommends that you test daily starting on day 11-12 after the first day of the last menstrual period. When the ovulation test is positive, you should ideally have sex on the same day and the following two days to increase the chance of pregnancy. Sexual intercourse in the days leading up to ovulation furthermore ensures sperm in the uterus and fallopian tube when ovulation starts.  You can also test the man's sperm quality with our sperm test from SwimCount: SwimCount Sædkvalitetstest – Gravidtid

When is ovulation expected and when should I start testing?

Use the form here to see when you are expected to ovulate or when you should start testing if you want to use ovulation testing. 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 lenght

Expected day of ovulation 

When to start taking an ovulation test

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

See our thermometers here: Termometre – Gravidtid

Source: Sundhed.dk, Rigshospitalet, Netdoktor.dk