To become pregnant you need to have sex (without contraceptives!) at the right time, ie the most fertile part of your cycle. This is usually during ovulation, when an egg is released from the ovaries.

When this happens depends on how long your cycle is. Remember that a cycle lasts from the first day of your period, to the first day of your next period.

In a normal 28-day cycle, ovulation takes place on the 14th day. In a 35-day cycle, it takes place on the 21st day, but conception is also quite common in the days leading up to ovulation.

To work out your ovulation date, either buy a test from the chemist, or make a temperature graph. Ovalution is closely linked to temperature, there is normally a brief drop in temperature just before ovulation, followed by a steady rise afterwards. Make sure you take your temperature at the same time each day, in the morning - you may need a special narrow range thermometre to register the tiny changes in temperature which indicate ovulation. Be careful though, these temperature graphs can be difficult to interpret, so don't worry about every little change!