Could the reason you haven't got pregnant be down to your blood type? Scientists in the US at New York and Yale University have recently discovered that women with type O blood are twice as likely to have a lower egg count and poorer quality eggs.
If you haven't got pregnant as fast as you thought don't automatically assume that you're infertile. Here are 10 more reasons why you might be having trouble.
It might seem that for some people, especially ones who get pregnant without trying, that it's straightforward but having a baby depends on everything being just right, including your lifestyle.
That's why we've got a list of 10 reasons that could explain why you're not pregnant yet. Have a look through and see if any apply to you and your partner, we've then got tips, advice and support to help you if they do. Don't leave having a baby to chance, let us help you.
1. You're not having enough sex!It seems like a straightforward one but the more you have sex the more chance there is that you'll conceive. A lot of couples, when trying for a baby, go from having sex maybe once or twice a fortnight to once a week and it might still not be enough.
2. You're having sex at the wrong timesHaving problems knowing when you're ovulating? Either you're struggling to work it out properly or just don't know where to start.
It's absolutely crucial when trying for a baby that you have sex when the egg, and your whole body, is ready to be fertilised and the only way you'll know this for sure is to know what happens during ovulation and what your cycle is. Or you could have sex every day just in case!
- 10 things you need to know about ovulation
- Ovulation date calculator
3. You or your partner smokeWhen you do get pregnant it'll be best for the baby if you gave up smoking anyway so why not give it a go while your trying.
Smoking lowers a man's sperm count and reduces your fertility so it will make getting pregnant a lot harder.
It even lowers your energy levels so you might not be having sex as much as maybe you should be.
- Visit our Stop Smoking Clinic for help and advice on quitting
4. You or your partner drink alcohol regularlyIf either of you have more than 4 units a week it can lower your chances of falling pregnant by a third.
In a similar way to smoking, it can affect your partner's sperm count, especially if he drinks every day, and give you both less energy.
It's also best to cut back on how much you drink when you're pregnant anyway so get a head start!
- Do you know how much you're drinking? Take our quiz to find out
5. Your diet isn't balanced enoughTo work at its best, your body needs a balanced diet.
This doesn't mean cutting out junk altogether or following a strict eating regime, it just means that you should eat everything in moderation.
And if you want to get pregnant you'll need to make sure you're getting all the vitamins and minerals you need.
There are even certain foods which actually boost your fertility like fish and wholegrains.
- Get more advice on eating to get pregnant
6. You or your partner are either underweight or overweightWomen who are classified as overweight or obese have a much lower chance of getting pregnant. This is because of the stress it puts on your whole body and the fact your energy levels are lowered.
Being underweight can be a problem too, especially if it's because you're not eating enough.
Not being an ideal weight can also affect your menstrual cycle which makes getting pregnant a lot harder and even more unpredictable.
If you're worried speak to your doctor who will be able to help you bring your weight into a healthy range.
They will also be able to tell you whether your weight problem is due to something else such as Polycystic Ovaries - a disorder that can make getting pregnant difficult.
7. You or your partner drink a lot of caffeineWhether it's through tea, coffee or fizzy drinks too much caffeine can lower a man's sperm count and affect your fertility too.
Ideally you should try to limit your caffeine intake to just one cup of tea or coffee a day.
8. You or your partner don't get enough exerciseThe more exercise you do the less body fat you will have which will make it easier to have a baby.
In the same way though, having too little body fat can mean you have an irregular cycle. This will make trying to pinpoint when you're ovulating near on impossible.
Other benefits to exercise are that it releases endorphins which in turn give you more energy.
The more energy you have the more likely you are to want to have sex more regularly, but it also means your body doesn't have to work as hard to keep you going.
Exercise also relieves stress. Chances are if you've been trying for a baby for a while it's all you think about and this can make you upset, stressed and depressed.
And don't forget that sex is fantastic exercise too!
9. You're obsessing about it too much.This may be easier said than done but try not to obsess about getting pregnant - the more you worry the less likely you are to get pregnant.
Stress can make your periods irregular and sometimes affect the releasing of an egg.
It can also put a lot of pressure on your relationship and can cause arguments and then you definitely won't feel like having sex!
Fertility expert, Zita West says: 'Sex can steadily become mechanical for so many couples; it is so hard for it not to. Many men suffer from 'performance anxiety' around sex if it seems their partners are only interested in having sex around the time of ovulation.
If a couple can keep their lines of sexual communication open and enjoy this aspect of their relationship for its own sake, the process will be less stressful all round.'
10. You and your partner aren't getting enough zinc and folic acidThis goes hand in hand with eating a healthy, balanced diet but even with a balanced diet a lot of people still don't get enough zinc or folic acid.
And when you're trying for a baby both are essential minerals your body needs.
Zinc makes sure that the sperm produced by your partner is good quality and it also reduces the risk of miscarriage.
Folic acid helps your body prepare for pregnancy by increasing the amount of healthy red blood cells and it also reduces the risk of having a baby with birth defects.
- Ovulation calculator
- Eat to get pregnant
- Visit our Conception section for more about fertility and getting pregnant