As Khloe Kardashian opens up about infertility, we find out how common fertility problems are - and how to fix them

Khloe Kardashian and Lamar Odom's infertility struggles aren't unusual - but how long does it take to get pregnant and when should you worry?

Khloe Kardashian has opened up about her and husband Lamar Odom's struggle to get pregnant - leading to her sister Kourtney offering up her womb as a surrogate.

Khloe explained her fertility troubles to her pregnant sister Kim Kardashian, on a recent episode of Kourtney and Kim Take Miami, revealing there's a medical reason behind her infertility.

Khloe Kardashian and husband Lamar Odom, have been TTC for a year ©Rex

Khloe, 28, explained that after a year of trying to conceive she went to the doctor for help and it was then that she discovered her cycle wasn't working as it should.

"Since I married Lamar its been awkward," the Keeping Up with the Kardashians star said.

"About a year ago we just said let's just let it happen – but when it didn’t happen Kim was like 'lets go to the doctor'.

"I found out I don’t ovulate and my uterus lining isn’t thick enough and I have to take pills to make my uterus lining thicker, and if that doesn’t get thicker I cannot carry a baby – sometimes it just doesn’t happen."

Conceiving a baby can take months or even years naturally so often couples try for some time with no luck before they seek medical help.

Infertility can be caused by a range of problems in both men and women, though in almost a third of cases, no cause can be identified.

Khloe struggles with infertility as sisters Kim and Kourtney Kardashian haven't had problems getting pregnant  …

Around 10 per cent of women of childbearing age have fertility problems. Khloe appears to have the most common cause of infertility - problems with ovulation.

This can mean that women stop ovulating (producing an egg) altogether, or that they ovulate at unpredictable times during the cycle, making it hard to know when the most fertile time to have sex is.

Other problems include fibroids (non cancerous growths in the womb), endometriosis (where the womb lining grows outside the womb), some medications and hormonal imbalances such as PCOS or thyroid disorders.

Men can also be infertile or have lower fertility, with low sperm counts and low quality sperm being the chief problems.

Lifestyle and fertility

Before you worry, or put yourself through rounds of tests and treatment, there are plenty of ways to increase your chances of conceiving naturally through lifestyle changes.

Living healthily with a good diet and plenty of exercise can make a big difference.

Living healthily and eating well can boost your fertility naturally ©Rex

If you're trying to conceive ensure you and your partner:

- Reduce alcohol consumption
- Eat a healthy, balanced diet with plenty of fruit and veg and limited processed meat
- Drink plenty of water - you should be sipping down eight glasses a day
- Get to a healthy weight - this is vital for both partners and especially for the potential mum as it lowers the risk of pregnancy complications
- Have sex every two to three days rather than every day to improve sperm quality
- Reduce stress levels
- Don't smoke

Women's fertility decreases with age so this may be a factor in how early you seek medical help. It's usually advised you try to conceive naturally for a year before starting any investigations. From the age of 35 fertility decreases more rapidly and natural conception after the age of 40 is quite low.

If you are an older potential mum, you may need to seek infertility treatment to improve your chances of getting pregnant. The man's age is less important, but studies have shown that men's sperm also decreases in viability as they gets older.

Surrogacy is quite a big leap, so it's not surprisingly Khloe dismissed Kourtney's offer. However, it can be necessary in some cases and celebrity mums including Sarah Jessica Parker and Nicole Kidman have increased awareness about the problems couples can face trying to become parents.