Assuming a couple does not have any obvious or significant health issues that may affect their fertility, using a home ovulation test can help to identify the time in the woman's monthly cycle when she is most likely to conceive. According to a UK study, while 91 per cent of women understand what ovulation is, more than a third are not confident that they know exactly when it occurs. A 2011 survey by Procter & Gamble (manufacturer of Clearblue) suggested that half of all couples could be trying for a baby at the wrong time.

Easy-to-use home ovulation kits can help to determine when a woman is at her most fertile. Products include Clearblue Digital Ovulation Test and First Response Easy-Read Ovulation Test. These work by detecting the body's production of LH, levels of which surge rapidly and peak 24 to 36 hours before ovulation. Packs contain a number of testing strips to be used on consecutive days around the middle of the woman's cycle.

The exact days of testing may vary depending on the usual length of her monthly cycle, therefore all test instructions should be read carefully. A test should be done once daily, using the first urine after sleep, starting from between day five and 20 of a woman's cycle (the actual start day will depend on her known cycle length).

Typically, home ovulation tests detect levels of LH. However, the latest offering from Clearblue also monitors oestrogen and indicates a wider fertility window (four days in total instead of just two days). Levels of oestrogen rise a few days before ovulation and can be detected in a woman's urine. These are identified as her days of 'high' fertility, whereas the surge in LH that occurs just before ovulation is when a woman's fertility is at its peak.