The simple fact is that you need to time it just right to ensure that sperm meets egg, and fertilisation occurs.

There are plenty of ovulation predictor kits around but these tests can be expensive, so it's well worth familiarising yourself with your body's own natural signs of ovulation. Obviously none of them are 100% accurate but they can signal that you're about to ovulate while others indicate that you've already ovulated.

1 Cervical Mucus Changes

As you start to approach ovulation the amount and consistency of your cervical mucus changes. When you're not ovulating, it has a thicker consistency or there may not appear to be very much of it at all (This can often be the case if you're taking a fertility drug! Also other medications like antihistamines can have the same effect so bear this in mind if you take these for hay fever). As you reach the point where you're about to ovulate, it becomes much more clear, watery and stretchy - almost like raw egg white in consistency - and there's more of it. It's much easier for sperm to swim through the cervical mucus when it reaches this consistency so take it as sign that your body is telling you you're fertile!

2 Increased Libido

Most women experience an increased libido around the time they ovulate: it's mother nature's way of ensuring you get pregnant. Research has shown that women had more sex around the time when their levels of luteinizing hormone, which peak around the time of ovulation, were highest. It usually kicks in a couple of days before you're due to ovulate, so if you really feel like it, follow your instincts and go for it!

3 Temperature Changes

Tracking and charting what's called your body basal temperature (BBT) is another natural way of predicting when you're likely to ovulate. Your BBT is your body's temperature when it's at rest, and it tends to rise slightly (by around 0.2 Â°C) just before you ovulate, and stays slightly raised just afterwards. It's the hormone progesterone that causes this rise - its levels increase just after ovulation. It can take a while to get the hang of this method and you'll have to take your temperature every day (first thing in the morning for accuracy, so have your thermometer on your bedside table ready to use even before you get out of bed, as moving around will raise your temperature), but charting when your temperature rises will help you pinpoint when in the month you tend to ovulate. The aim is to have plenty of sex in the couple of days leading up to that time, since that rise in temperature indicate you've already ovulated.

4 Changed Cervical Position

The position of your cervix (the neck of the uterus) changes slightly as ovulation approaches, to ensure it's softer and more open when you're fertile - thereby making it easier for sperm to swim up through the cervix to meet the egg. To check its position, slide a clean finger into your vagina at an upwards angle. If ovulation isn't near, you should be able to feel your cervix (it feels like the tip of your nose) but if you are about to ovulate it'll be higher and more difficult to reach.

5 Tender Breasts

Your body treats every ovulation as a practice run for pregnancy, so pregnancy hormones build up on the offchance. Just as they cause tender breasts when you have hit the jackpot, they can cause tender breasts in the run up to ovulation.

6 The Countdown

Counting days in your menstrual cycle is the easiest way to track ovulation. If you start using this method, it can help you pinpoint the week when you're most likely to ovulate over the next few months and you can plan to have sex at least every other day during that week. If you have irregular cycles or even miss periods from time to time this method probably won't work for you.

7 Pain and Spotting

Around 20% of women experience 'Mittelschmerz', where the action of the egg bursting from its follicle on the ovary causes cramps on one side of the lower abdomen. You may also experience slight spotting that causes a pinkish tinge to your cervical mucus.

8 Bloating

If you find the zip on your jeans a bit harder to do up but you know you're definitely not pregnant it could be a sign of ovulation, as the hormones released around the time you ovulate tend to cause water retention.

9 Heightened Senses and Increased Energy

Many women report keener senses of vision, smell and taste around the time they ovulate. You also may have mood swings and feel a burst of increased energy prior to ovulation.

10 Positive Result on an Ovulation Predictor Test

Ovulation predictor kits work in a similar way to home pregnancy tests - you wee on a stick and it registers the presence of luteinizing hormone, which surges just before you're about to ovulate. The tests are expensive and if you ovulate irregularly you may go through more than one monthly kit at a time, but can be useful if you're not getting the hang of other natural methods of detecting ovulation.

You can buy special ovulation prediction kits, which test your temperature or hormone levels to find out when you are at your most fertile.