Despite the positive results of small studies and a widely held belief in its benefit, the practice of keeping female patients immobilised after intrauterine insemination has no beneficial effect on pregnancy rates, according to results of a large randomised study presented here at the Annual Meeting of ESHRE in Helsinki. "Indeed," said investigator Joukje van Rijswijk from the VU University Medical Center Amsterdam, "it even tends to the opposite."
Behind her conclusions lies a large randomised comparative study in which 479 patients with standard indications for IUI (unexplained or mild male factor infertility) were randomly assigned to 15 minutes of immobilisation immediately after insemination or to immediate mobilisation. With most patients having several cycles of IUI in their treatment course, the comparison was based on a total of 950 cycles of immobilisation and 984 cycles of mobilisation.
Results showed that the cumulative ongoing pregnancy rate per couple (that is, after the total course of treatment, which in some cases ran to six cycles) was comparable between the two groups - a pregnancy rate of 32.2% after 15 minutes of immobilisation and 40.3% after immediate mobilisation. These differences were not statistically significant, despite the trend, indicating no benefit from a brief period of bed rest after insemination. "In our opinion," said Dr van Rijswijk, "immobilisation after IUI has no positive effect on pregnancy rates, and there is no reason why patients should stay immobilised after treatment."
She acknowledged that these results were "in disagreement with the literature", from which a widespread acceptance of bed rest after IUI had evolved. A smaller study published last year from the Middle East found that ten and 15 minutes of immobilisation following IUI (compared to five minutes) had a beneficial effect on pregnancy rates. However, the results were based on just one cycle of treatment and not on the more real-world context of multiple cycles. Another smaller Dutch study published in 2009 also found that 15 minutes bed rest improved pregnancy rate and "should be offered to all women treated with intrauterine insemination".
"It was these previous studies showing a benefit of bed rest which prompted us to perform this study," said Dr van Rijswijk. "Our goal was to replicate the results. There's always a possibility that a positive outcome in studies is the result of chance. We also know from other studies that sperm cells can reach the fallopian tube five minutes after intravaginal 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", which, she added, is usually carried out in a supine position with the knees raised.
"We believe our results in such a large randomised trial are solid, and sufficiently strong to render the recommendation for bed rest obsolete," she said.
Asked if bed rest might also be of no help in natural conception plans, Dr van Rijswijk said the two insemination techniques are just too different to generalise, and she pointed out that as far as she is aware there have been no randomised trials to test the efficacy of a short period of immobility after the attempt.
European Society of Human Reproduction and Embryology