Timing is important to achieve pregnancy in intrauterine insemination, but available evidence doesn't support using one timing method over another.
Could a particular timing technique used to synchronize ovulation with insemination lead to more successful pregnancies?
The question, posed by the Cochrane Menstrual Disorders and Subfertility Group, turned out to be one that can’t yet be answered by available scientific evidence.
- Evidence does not exist to indicate the best timing method for a successful IUI pregnancy, a Cochrane analysis found.
- More high-quality studies are needed to better understand which, if any, timing technique used to synchronize ovulation with insemination has the best outcomes.
Intrauterine insemination (IUI) is the first-line treatment for many subfertile couples who have an ovulatory cycle, at least one open fallopian tube, and sufficient spermatozoa, explained the researchers in background information. Since IUI must be performed around the moment of ovulation given that the egg and sperm have only limited survival time, the researchers wondered if one timing technique resulted in better outcomes than other techniques for IUI.
After reviewing 18 randomized controlled trials, all comparing different timing methods used in one treatment cycle for IUI, the researchers found insufficient evidence to support recommending one method over another. However, most of the evidence was deemed to be of low or very low quality, with many of the trials having poorly described study methods or a lack of precision, the Cochrane researchers wrote.
So, when the various timing methods were compared, the analysis found no differences in live birth rates or pregnancy rates or in the occurrence of reported adverse events, such as multiple pregnancy, miscarriage, and ovarian hyperstimulation syndrome.
The analysis left the Cochrane reviewers to conclude not that the timing method was inconsequential to IUI success but that more research is needed into the matter.
The reviewers also looked at data involving when to administer human chorionic gonadotropin (hCG) injection and studies relying on luteinizing hormone (LH) surge detection.
“The usefulness of urinary LH monitoring is hampered by the possibility of false-negative results which can cause inaccurate timing and significantly reduce pregnancy rates,” the authors wrote. “On the other hand, the ease of performing a test at home, the lower costs and the non-invasiveness are advantages. Limitations of timing by ultrasound and hCG administration are frequent hospital visits and the occurrence of premature LH surges or the possibility of triggering ovulation in the presence of an immature follicle. The major advantage of this hCG method is the clinical predictability of the ovulation.”