If you have irregular cycles, it is usually more difficult to self-determine the date of ovulation, and as a result, to plan intercourse that maximizes your chances of conception. If a woman doesn't use any method to help determine her fertile days and ovulation date (BBT charting or USG monitoring), and has irregular cycles (especially if they are long) it may take her longer to get pregnant. (Can a long cycle make becoming pregnant difficult?) If the irregular cycles do not stabilize within a couple of months, talk to your doctor to determine the cause.