Mother and Baby


Section: Getting Pregnant

You’ve been having periods every month since you were a teenager, but other than unexplained rage (oh, that’s why) or stocking up on tampons at the right time, chances are you haven’t given it much thought. Get ready to go back to school and learn about just what happens in your body to help you make a baby.

Until you started trying for a baby, you probably never stopped to think what happens during your monthly cycle. But now you’re desperately trying to work out when you are at your most fertile. Let us clear up any confusion.

What is ovulation?

Every woman is born with all the eggs she will release over the roughly 500 periods she’ll have between puberty to menopause.

Once a month an egg ripens – usually just one – and is released from one of two ovaries. It then travels down the fallopian tube, which links the ovary and the womb (uterus). That is called ovulation.

Day one of your cycle is always counted as the first day of your period, and it can last from around 22 to 36 days – or even shorter or longer in some cases. The average menstrual cycle is 28 days, but around half of women have a cycle that varies from one month to the next.

Why is ovulation important for conception?

If the egg is fertilised by any sperm it meets on its travels, it embeds itself in the thick lining of the womb, which has been preparing itself for the egg’s arrival. If not, the lining falls away and that is your period. The whole process from start to finish is controlled by a series of hormonal releases. 

For the egg to be fertilised, it needs to meet some sperm in the fallopian tube during its 24-hour lifespan.

But don’t panic, you don’t have to aim to have sex on a specific day. Mother Nature has made things a bit easier, in that sperm can live in the woman’s body for between five to seven days.

This gives you a fertile window of around six days – that’s five days before you ovulate and the day of ovulation itself.

Signs of ovulation

Common signs of ovulation include slightly increased body temperature, vaginal mucus and increased sex drive. One in five women also experiences slight ache in a belly or heavy sore breasts. Read more about signs of ovulation here.

When are you most fertile?

Ovulation happens about halfway through your cycle. Some women may recognise some tell-tale signs they are ovulating.

But the key to working it out is to know how long your cycle usually is and count backwards.

‘You need to think that you ovulate 14 days before your next period, so you need to count backwards from when your period is due,’ says Helen Kendrew, matron at the Bath Fertility Centre. If your cycle is 28 days, then that would be day 14, right in the middle, but if your cycle is shorter or longer, then that could be day 10 or day 20, she explains. Using an ovulation calculator can help you easily keep track of this.

For some women cycle length may vary a little, which is why experts advise regular sex every two to three days to boost your chances whatever your pattern.

What is an ovulation calculator and how can it help?

An ovulation calculator helps you to work out the best days for trying to conceive. All you need to do is pop in the first day of your last period and the average length of your cycle (the number of days between your periods). Give it a try here

What is an ovulation predictor kit and how can it help?

Using an ovulation calculator, looking out for ovulation signs and having regular sex are all good methods. However, it’s not so easy for women with irregular cycles, or those whose schedules are too busy for three-times-a-week sex. That’s when ovulation predictor kits (OPK) come in handy. 

There are two types of OPK: salivary and urine-based. You must take one test each day throughout your cycle until you find out your ovulation day. Standing at about £10 to £15 kits with enough tests per cycle are available online and in most supermarkets. 

Try our ovulation calculator 


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