According to FertilityIQ data, nearly 30% of fertility patients are given a diagnosis of “unexplained infertility.” So how does one decide between starting with two very different treatments, namely medicated IUIs or full-blown IVF, when we don’t even know what the culprit is? Is there a major difference in outcomes in this population and if so, how do we balance that with the greater cost and intensity of IVF?

Why This Study Is Special

Researchers in the U.K. took garden-variety couples with “unexplained infertility” and prospectively pitted their success rates based on whether they did 3 medicated IUIs or 1 round of IVF (using as many frozen transfers as was available from that cycle). The prospective nature meant the two groups were virtually identical and very little inference or statistical manipulation was needed to make a call.

What Was Tracked & What They Found 

The endpoint was singleton live births and the group receiving IUI had a 9% success rate after the first 1st cycle and a 25% success rate by the 3rd IUI. Compare that with the IVF group, which enjoyed a 31% success rate.

So IVF was a better option, right? The authors disagreed with that on two accounts. First, that 6% absolute difference (31% vs. 25%) fell within the margin of error and could have been a result of the study’s sample size.

Second, they deduced on cost-per-live birth rate basis, IUI was the more efficient approach. In America, medicated IUI’s typically cost $500 - $3,000 while IVF costs on average $18,000. Thus, if 3 IUIs deliver similar results anywhere near 1 IVF, the author’s observations on economic efficiency likely apply to the US as well.

The Study’s Limitations

There are a few weaknesses of this study. First, the sample size should have been bigger: 6% is a major difference, yet falls within the margin of error. Not great. Second, the group excluded couples where the woman was over 38 years of age and so the findings may not apply to all couples. Furthermore, these were patients who had been trying for over a year and hadn’t yet done either IUI or IVF. So does this finding broadly apply to many patients who’ve just been given an “unexplained” diagnosis? Possibly, but possibly not. Third, this was a single center study abroad, and treatment doses and approaches may not reflect what any given US clinic might do.

The Takeaway

If you're a couple or patient that meets the classical definitions of “unexplained infertility," are just starting treatment and in a situation where the woman is under age 38, you may not need to advance automatically to IVF.