As the pressures of modern day life bite, couples are waiting later and later to start planning their families.
As a result, over the last two decades fertility problems have increased dramatically, with one in four couples planning to have a baby facing problems conceiving.
There is a host of things you can do to help your chances, improving your diet, abstaining from drinking alcohol and restricting your caffeine intake.
But, fertility expert Dr Marilyn Glenville said the position you and your partner assume during and immediately after having sex, can ‘significantly’ alter your chances of becoming pregnant.
The reason, she said, lies in passage the sperm take into the vagina, and on to the fallopian tube.
The man-on-top position has the best chance of getting a woman pregnant.’
But, she cautioned, there are no scientific studies to back up the theory.
‘The rationale is that this position allows for deep penetration so the man’s sperm can be ejaculated as close to the cervix (the opening of the womb) as possible,’ Dr Glenville added.
‘This gives the sperm cells a flying start on their long journey.
‘The closer they are to the ripe egg waiting in the fallopian tube, several centimetres further up in a woman’s body, the more likely they are to reach it.’
She said, logically, any position that goes against gravity, such as the woman on top, or having sex sitting or standing up, ‘discourages the sperm’s journey upward and is thought to deter conception’.
Dr Glenville added: ‘If a man enters a woman from behind, especially if she is kneeling in front of him so she is at an angle, with her bottom higher than her head, it is said to encourage conception.’
But for those couples who love having sex in the ‘spoons’ position – where both partners face the same way and the man penetrates his partner from behind – Dr Glenville has bad news.
It is not thought to aid your chances of getting pregnant, ‘because the penetration angle is not so deep’.
‘The chances might be maximised if the woman leans the upper half of her body a little away from her partner, pushing her bottom against him,’ Dr Glenville added.
‘The only exception to this would be if you have a retroverted uterus.
‘Normally the womb is in an up-and-down position, or tipped towards the front.
‘But in some women, the womb tilts backwards.
‘It does not affect fertility but sometimes can make intercourse painful, or difficult.
‘The best positions for intercourse if you have a retroverted uterus are either rear entry or with the woman on top and this will help the sperm to get as close to the cervix as possible.’
As well as the position you choose to have sex, some experts argue a woman’s ability to orgasm can make a difference when it comes to conceiving.
Two British biologists, Robin Baker and Mark Bellis, investigated the ‘upsuck hypothesis’.
They discovered that when a woman climaxes, any time between a minute before and 45 minutes after her lover ejaculates, she retains significantly more sperm than she does after non-orgasmic sex.
In addition, their research results indicated that the strong muscular contractions associated with orgasm create a partial vacuum, which help to suck the sperm from the vagina to the cervix, where it’s in better position to reach an egg.
Dr Glenville added: ‘Evolutionary psychologists are suggesting that in the past orgasm could have served a purpose – unconsciously – in favouring the man that a woman wants to father her child.
‘So the woman would have an orgasm with one man who she would like to have children with and not another.
‘But it is important to remember that a woman does not need to have an orgasm in order to conceive.
‘So do not beat yourself up, if you do not have one every time you have intercourse.’