In Vitro Fertilization or Intrauterine Insemination in Unexplained Infertility.

Four cycles of IUI with ovarian stimulation in couples with unexplained infertility produced a 31% cumulative live-birth rate versus 55% with one IVF cycle.

• Why it matters: Guidelines favor IUI as first-line for unexplained infertility, but direct randomized comparisons of cumulative live birth between IUI and IVF are limited.
• What they did: In a sequential multicenter randomized trial, couples were assigned to IUI (up to four cycles) or first-line IVF (one complete cycle with all embryos transferred), with optional crossover to additional IVF.
• The result: IUI was not noninferior: the adjusted risk difference was -24 percentage points (95% CI, -31 to -16) for stage 1 cumulative live birth, while stages 1–2 were similar (70% vs 71%).