Irregular periods indicate that whether you are ovulating irregularly or you are not ovulating at all. So first and foremost you need to find out the cause of your irregular periods. It could be a hormonal imbalance, PCOD or a polycystic ovarian disease, thyroid disorders or a pituitary or adrenal imbalance. If it is anything concerned with pituitary or adrenal or thyroid problem you should consult an endocrinologist to revert back to normal periods. If it is polycystic ovary which is very common (10 to 15% of woman of reproductive age group) you will have to treat this. General treatment for polycystic ovary is have a good sleep, reduce stress, weight reduction, etc along with that you can take some ovulation induction drugs like clomiphene citrate or HMG or FSH. Apart from this when all these are ruled out you need to know when are you ovulating, when you need to have sex, to have a pregnancy. There are a few parameters with which you can find out whether you are going to ovulate. May be you can use an ovulation kit. Normally it depends on a hormone called LH or a Luteinizing Hormone which is secreted by the pituitary which gives a signal to the ovary to release the ovum. This LH increases slightly just before the ovulation. Once this increase happens the ovulation happens after 24 to 36 hours. This LH hormone is present in the urine. so it is basically a urine test. Take an ovulation kit, put a drop of urine, see whether it is showing positive result. If it is negative please repeat it after a day or two. Once it shows positive that means you are going to ovulate in another 24 to 36 hours. So you will have to time your sex during that time because the semen is active in the uterus for 24 to 48 hours. If the ovulation happens after 24 hours when it reaches the uterus the egg is active only for 12 to 24 hours. So by the time the egg reaches the uterus semen will already be there waiting for fertilization. That is one of the easy and simplest method to find out whether you are ovulating or not and how to time your sex during ovulation. Suppose you don’t want to get your ovulation kicked and you want to depend on some simple method the second one is called as a bbt chart or a basal body temperature chart. This is a chart where every day early morning your temperature is measured by a thermometer and put it in a graph. Normally just before ovulation there will be decrease in temperature by half a degree and then it rises a little more. If you keep doing you will come to know when there is a decrease in the temperature and there is a rise. Then you know this is the time you are going to ovulate and you should plan your sex during that time or 4-5 days. It all depends on the accuracy with which you record your temperature and you put it in a graph. The third much more simpler method is normally the cervical mucus i.e. the discharge from the cervix is very thin after periods. It starts becoming thicker during ovulation. So when you test the cervical mucus in case the mucus becomes sticky that means that is the time you are going to ovulate. These are the simple methods. More reliable would be like to go to a doctor, get a follicular monitoring that is done by an ultrasound scan. Doctor will do the follicular scan starting from the eighth day of your periods to see the size of your follicle. The follicle will have to grow up to 18 to 20 millimetres. That means your egg is ready to be released. More reliable method by which you can plan your sex and plan for a pregnancy.