HELSINKI, FINLAND – A brief period of immobilization after intrauterine insemination did not improve pregnancy rates and was actually associated with a slight reduction in the pregnancy rate in a large single-center, randomized controlled trial.
The findings conflict with those of some prior smaller studies and contradict a widely held belief in the benefit of immobilization, which is usually carried out while the patient is in a supine position with the knees raised, Joukje van Rijswijk, MD, reported at the annual meeting of the European Society of Human Reproduction and Embryology.
In 479 patients with idiopathic or mild male subfertility and an indication for IUI who were randomized to 15 minutes of immobilization following IUI (950 cycles) or immediate mobilization (984 cycles), the cumulative ongoing pregnancy rate per couple was 32.2% and 40.3% in the groups, respectively (odds ratio, 0.70). The difference between the groups was not statistically significant, said Dr. van Rijswijk of VU University Medical Center, Amsterdam, The Netherlands.
Randomization in the study was stratified for the diagnosis of idiopathic or mild male subfertility. After adjustment for duration of subfertility, the difference between the group still did not reach statistical significance (odds ratio, 0.72), Dr. van Rijswijk said.
IUI is an established treatment for idiopathic and mild male subfertility, and while several factors are associated with pregnancy outcomes, the role of direct mobilization has remained controversial. Two recent studies showed a beneficial effect but were of questionable quality. For example, one of the studies found that 10 and 15 minutes of immobilization, vs. 5 minutes, had a beneficial effect on pregnancy rates, but the results were based on just one treatment cycle and “not on the more real-world context of multiple cycles,” according to an ESHRE press release.
The responsible mechanism for the benefit of immobilization remains unclear, Dr. van Rijswijk said, explaining that it is known from other studies that sperm cells can reach the fallopian tube 5 minutes after intravaginal insemination and 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,” she said.
“In our opinion, immobilization after IUI has no positive effect on pregnancy rates, and there is no reason why patients should stay immobilized after treatment,” she concluded, adding that the findings are “sufficiently strong to render the recommendation for bed rest obsolete.”
As for whether immobilization is also unwarranted for natural conception, Dr. van Rijswijk said the two insemination techniques are too different, thus the findings are not generalizable.
She reported having no relevant financial disclosures. The trial was funded by the VU University Medical Center.