There are so many old wives' tales about conceiving a baby it can be hard to know which to believe. Fertility expert and consultant gynaecologist Sara Matthews sorts the myths from the facts.

Are you more likely to have a boy if your partner has brothers?

NO! It's true the father does determine the sex of the baby, but sex selection is a somewhat random process. Basically, there's no evidence that, if you or your partner comes from a family with lots of boys, it will have any impact on the sex of your baby. So don't worry if your partner's family haven't had girls or boys for a few decades. You could break the mould!

Is it easier to get pregnant second time around?

YES! It's amazing you can even have sex, considering all those sleepless nights with a baby or toddler in the house! Couples who already have children are usually pregnant again within six months of trying, whereas it may take up to a year first time around. However, this doesn't include couples who had fertility problems first time around.

Does having sex in the missionary position or with the woman on top improve the chance of conceiving a girl?

NO! There's no scientific evidence to suggest that this is true at all. It's also not true that boys are more likely if you try positions where your partner enters you from behind or if you have sex standing up. But variety is the spice of life, so keep trying!

Can sperm quality be affected by wearing tight pants?

YES! Let's get down to basics here: testicles hang outside the body because sperm production is best when they are kept below normal body temperature. That's why men who work in a hot environment, such as welders and firefighters, tend to have lower sperm counts. Regular saunas and hot spas or baths may have a similar effect.

Tight pants hold the testicles so close to the body that sperm production can be lowered, so ask your man to wear boxer shorts.

And tight jeans can influence your fertility, too, by increasing your risk of endometriosis. So it may be best of you hop out of those super skinny jeans (at least you'll be able to breathe out!).

If you have an orgasm, are you more likely to conceive a boy?

NO! Boy sperm are lighter than girl sperm so they might swim or surf a bit faster towards the egg if you have an orgasm, which makes the womb muscles contract in waves. However, there's no scientific evidence that they are any more likely to fertilise the egg first.

Does eating some foods help to conceive a boy or a girl?

POSSIBLY Studies have shown that eating a diet high in potassium and sodium foods like bananas, spicy and salty foods and red meat may increase your chances of conceiving a boy. On the other hand, eating calcium- and magnesium-rich foods like milk, cheese, fish, rice and nuts can result in the birth of a girl. But experts agree that, to have a healthy pregnancy, you need to have a balanced diet with a wide range of nutrients, so it's not really a good idea to follow a restricted diet when trying to conceive.

Can douching the vagina with vinegar after sex help you to conceive a girl?

NO! The theory behind this myth is that vinegar makes the vagina more acidic, which is said to favour female sperm, while an alkaline environment favours male sperm. In practice, all it will do is remove any sperm that are still lurking in the vagina, put you at risk of a vaginal infection and make you smell like a bag of chips! The vagina is an acidic environment in any case, and this rarely changes, whereas the acidity of a man's semen depends on his diet so it can vary more.

If you have two boys or two girls, are you more likely to have another one in the next pregnancy?

YES! Statistics suggest that you are 75% more likely to conceive another boy or girl if you already have two of the same sex. Although sex selection is random, it's possible that some men simply produce better quality X (female) or Y (male) sperm, resulting in large families of girls or boys respectively. Scuba divers tend to have families of girls, as the more delicate Y sperm don't survive the effects of pressure at depth so well. Perhaps your partner could consider taking it up as a hobby if you are on the way to having your own football team!

Are boys more often conceived on odd days of the month?

NO! It's said that boys are best conceived at night on odd calendar days and at the time of a quarter moon; girls, meanwhile, are guaranteed by making love in the afternoon at the time of a full moon on even calendar days. It may be romantic, but sadly, it doesn't work.

What about having him dip his erect penis in freezing water before making love to improve the chance of conception?

Um… NO! This will simply make keeping the erection almost impossible! Yes, sperm like to be kept slightly below body temperature, but chilling them at this stage of the proceedings won't be of any benefit they might even stop swimming.