The most effective time to conceive is during your fertile period, which can last up to six days every month. These six days are the five days leading up to, and the day of, ovulation, when your body releases an egg. Your egg will survive for about a day once released. But sperm can survive for up to a week. Hence there is a six-day window for sperm to meet an egg. You are most likely to conceive if you have sex one or two days before you ovulate. If you want to be more precise, though, you will need to work out when you will ovulate. When you'll ovulate in any given cycle depends on:
•     the length of your menstrual cycle
•     how regular your periods are
A menstrual cycle can be as short as 22 days or as long as 36 days. On average, a woman gets her period between 12 days and 14 days after she's ovulated. If you have a 28-day menstrual cycle, you're likely to ovulate around the middle of your cycle (day 14). If you have a short cycle, you could ovulate within days of your period ending. A long cycle could mean that you won't ovulate until two weeks after your period has ended. If your menstrual cycle is different from one month to the next, your fertile window may also vary by about a week between each period. That's why it's best to have sex every two to three days throughout your cycle. It's more effective than focusing your efforts only on the days you think you're about to ovulate. Also, sex every two to three days improves the quality of sperm compared to daily sex.
Irregular periods do not necessarily mean that you are less fertile than women with regular periods. However, if your periods are irregular or are more than 36 days apart, it is worth seeing your doctor.
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