Although some women are very good at predicting ovulation, if 100 women use the method perfectly and according to teaching instructions, 2 women will get pregnant during any given year. This figure increases substantially if the methods used are not those taught. A couple is more accurate after six months of trying and many couples use the techniques in combination with other methods such as condoms or a diaphragm. Other couples use the technique when it would not be a disaster if pregnancy occurred such as when spacing between children.

The fertile time

The fertile time of the month is seven days before and 24 hours after ovulation. This is because sperm can survive for up to seven days and a female egg for 24 hours. If a woman is able to accurately predict her time of ovulation, then she and her partner can prevent pregnancy by avoiding sexual intercourse during this time. Furthermore, if a couple are trying to conceive, then they can maximise their chances by having intercourse during their most fertile time (just before ovulation).

Mittlesmertz

Mittlesmetz is the name given to the sensation some women get during ovulation. This is a pain that occurs in the lower part of the tummy during ovulation. It occurs regularly every month. The side of the tummy it occurs varies dependant on which ovary is producing the egg.

Not all women get Mittlesmertz but those who do can use this as a predictor of ovulation. A woman is fertile for 24 hours after Mittlesmertz. After this time she is unlikely to conceive until seven days before she next ovulates.

Body temperature charts

After ovulation your basal body temperature (BBT) rises by about 0.2 – 0.4 oC. Your BBT is your temperature before you get out of bed in the morning and before you have anything to eat or drink. If you use a chart, you can use you body temperature to predict a safe period in which to have intercourse and avoid pregnancy. The rule is that if you have recorded temperatures for three days in a row which are higher than all the previous six days, then you can have sexual intercourse and avoid pregnancy until your next period. The rise in temperature is an extremely small one. Therefore it is difficult to detect using a standard thermometer. You should use a digital thermometer or a specially designed fertility thermometer. The changes in temperature can be inaccurate in the following circumstances;

• Not the BBT – If the temperature is taken at any time other than the early morning before getting out of bed and having something to eat or drink.
• During illness – Your temperature can change during an illness.
• Taking drugs – Drugs such as aspirin and paracetamol alter your BBT.

Cervical secretions

Cervical secretions also change nearing ovulation. A woman wanting to predict the timing of ovulation is advised to feel for her cervix and recognise the differences in her mucous at different points in her cycle. The cervix can be felt at the top of a woman’s vagina and is a firm, rubbery structure.

After a menstrual period no cervical secretions are felt and the cervix feels dry to touch. The secretions then change in amount and texture. Firstly, the secretions are sticky and moist. They are cloudy or a milky colour. When this occurs, this is the start of the fertile time.

At the most fertile time before ovulation, the mucous becomes like raw egg white and can be stretched. This is called the Spinnbarkheit effect. After ovulation the cervix becomes dry again as secretions can be felt.

Cervical palpation

Cervical palpation is feeling your cervix with your finger. The cervix changes in consistency and position with different points in your cycle. Some women can recognise these changes and use them for predicting ovulation.

Cycle length

The length of a menstrual cycle varies with different women. If a woman calculates the length of her shortest of six cycles, then subtracts the number 20 from the number of days duration of that cycle. Then the result is the number of days following the onset of menstruation that it is normally safe to have intercourse.

Other changes

Some women notice changes in their breasts, mood, skin or libido that can help them to predict ovulation.

Persona

Persona is a kit that can be bought fromt he chemist it helps a woman predict ovulation and may assist with natural family planning.