A 38-year-old woman with unexplained infertility for 3 years has been advised IUI. Controlled ovarian stimulation (COS) for IUI uses clomiphene. Which statement about IUI outcome is most evidence-based?

• A IUI with COS triples pregnancy rates compared to IUI alone in unexplained infertility
• B IUI with COS has similar pregnancy rates to expectant management in unexplained infertility (NL-IUI trial) ✓
• C The HART trial showed IUI success rates equivalent to IVF in unexplained infertility
• D IUI should always be attempted for at least 6 cycles before proceeding to IVF

Explanation

The NL-IUI trial (Netherlands) and I-IUI trial showed that in unexplained infertility, IUI with mild ovarian stimulation had similar cumulative pregnancy rates to expectant management at 6 months, challenging its routine use. However, IUI with COS remains widely practiced as it can shorten time to pregnancy in selected patients. The I-START trial and subsequent meta-analyses suggest a modest benefit of IUI+COS over IUI alone, with per-cycle pregnancy rates of approximately 8–15% vs. 5–8%. Current NICE guidelines suggest up to 6 cycles of IUI in unexplained or mild male factor infertility before IVF, but this is resource-dependent. Age (>36 years) and duration of infertility favor earlier IVF referral.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

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Written and medically reviewed by the StethoPrep medical team.