Lying on back after sex ‘does NOT raise chance of conceiving’

THE long-held belief that if you want to improve your chances of conception you should lie with your knees up after making love is a myth, scientists say.

For lying down after sex does not increase a woman’s chances of getting pregnant, a study shows.

Fertility clinics have for years recommended that women stay immobile with their knees in the air after artificial insemination. But the study found little difference in conception rates between patients who followed this advice and those who got up immediately. There was even evidence that getting up improves pregnancy chances.

Scientists say the same should be true of women seeking to conceive naturally.

Researchers from the VU University Medical Centre in Amsterdam studied 479 women undergoing fertility treatment. All were believed to be having difficulty conceiving because of a fertility problem in their male partner.

Half the women had to stay immobile for 15 minutes in bed after artificial insemination, on their backs with their knees in the air and feet flat on the bed.

The other half were asked to get up and carry on with their daily activities.

The researchers found that after a total course of treatment – which in some cases included six cycles of intrauterine insemination (IUI) – 32 per cent who rested with their knees up got pregnant. Of those who were ‘immediately mobilised’ after sex, 43 per cent became pregnant.

Study author Dr Jouke van Rijswijk, who presented her research to the European Society for Human Reproduction and Embryology in Helsinki, said: ‘In our opinion, immobilisation after IUI has no positive effect on pregnancy rates, and there is no reason why patients should stay immobilised after treatment.’

She said that the results ‘were in disagreement with the literature’ and a study last year from the Middle East found that 15 minutes of immobilisation, compared with five minutes of bed rest, did boost pregnancy rates.

But unlike her study, this was based on only one cycle of treatment, rather than looking at the multiple cycles which better reflect the reality for many women undergoing fertility treatment.

A previous Dutch study also recommended 15 minutes of lying down but Dr van Rijswijk said: ‘We also know from other studies that sperm cells can reach the fallopian tube five minutes after insemination and that they can survive for several days in the womb.

‘Why should bed rest affect that? There’s no biological explanation for a positive effect of immobilisation. We believe our results in such a large randomised trial are sufficiently strong to render the recommendation for bed rest obsolete.’

Professor Adam Balen, consultant in reproductive medicine at Leeds Teaching Hospitals NHS Trust, said there was a widely held belief that the effect of gravity would hinder conception.

He said: ‘What’s very unhelpful in all biology textbooks is the pictorial representation of the female anatomy. So many women think that when you get up everything is just going to fall out. But anatomically that is not going to happen.’

Nick Macklon, professor of gynaecology at Southampton University, said that while the Amsterdam study did not apply to natural conception, there was no reason for women to think they ‘need to lie down for 15 minutes afterwards – unless they particularly want to’.