healthHealth and Medicine

Biologists Just Busted This Long-Standing Sex Myth


Robin Andrews

Science & Policy Writer

That's 15 minutes saved, then. Phil Jones/Shutterstock

Despite the fact that it’s happening all the time all over the world, there’s a fair bit that researchers don’t know about sex and pregnancy. A group of sex-pondering scientists decided to take on a few persistent pregnancy myths, and, presenting their work at the annual meeting of the European Society of Human Reproduction and Embryology, it looks like they’ve busted another one – namely, that bed rest after insemination increases the chance of a successful conception.

A team of researchers at the VU University Medical Center (UMC) in Amsterdam decided to test this old wives’ tale by randomly assigning 479 women receiving intrauterine insemination (IUI) – a process wherein sperm cells are directly injected into the uterus – to either post-IUI motion or 15 minutes of bed rest.


The majority of women underwent IUI treatment, many of which completed several rounds of it. In total, 2,000 IUI cycles were performed. As it turns out, pregnancy rates of the bed rest group were around 32.2 percent, whereas those that stood up immediately afterwards and had a bit of a meander around the room had an average success rate of 40.3 percent.

So although it may seem that the opposite of the old wives’ tale is actually true, these rates aren’t divergent enough to be statistically significant. Overall, then, there appears to be no benefit in doing either after being inseminated.

As reported by Medical Daily, it appears that this myth has actually been supported by a previous study, in that up to 15 minutes of rest after IUI appeared to give study participants a boost in their ability to get pregnant. However, these results were based on a single round of treatment, and only in after three to six rounds of IUI are pregnancy rates significantly raised, by as much as 80 percent. Other small-scale studies tend to agree with these findings, though, which means this new study is in disagreement with the preexisting literature.

“It was these previous studies showing a benefit of bed rest which prompted us to perform this study,” Joukje van Rijswijk, an expert in obstetrics and gynaecology at VU UMC, said in a statement. “Our goal was to replicate the results. There's always a possibility that a positive outcome in studies is the result of chance.”


Rijswijk points out that many other studies show that sperm cells reach the fallopian tubes five minutes after initial insemination occurs, 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 immobilization.”

Although she cannot be sure whether natural conception methods – sex, essentially – followed by bed rest would improve the chances of a successful pregnancy, Rijswijk and her team are very confident about their study looking at IUI. “We believe our results in such a large randomized trial are solid, and sufficiently strong to render the recommendation for bed rest obsolete,” she concludes.

Myth busted, then? It's looking likely.


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