When to move from IUI to IVF: how many cycles and for whom

IUI works by bringing sperm closer to the egg at the right time, but it relies entirely on natural processes: the egg must be released, the tubes must be open to catch and carry it, and the sperm must be able to fertilise. IUI therefore makes sense when these conditions are met: at least one open tube, a reasonable number of motile sperm after preparation, and a woman who ovulates or can be helped to ovulate.

The typical situations where IUI is a reasonable first step are unexplained infertility in younger women, mild ovulation disorders, a mild male factor, and some other cases. In these cases IUI offers a real chance with a small intervention, and that justifies trying it.

The chance of pregnancy per IUI cycle is modest, usually in the order of a few per cent up to around 10–15 per cent depending on age and cause. What matters is that the cumulative chance rises over the first cycles and then plateaus: most pregnancies that will come from IUI happen within the first 3 to 4 cycles. After that, each additional cycle adds little and costs time.

Guidelines and good practice therefore suggest that, if there is no pregnancy after 3–4 properly done cycles, it is time to review the plan and discuss IVF, not to continue 'one more time'. The exact number depends on age and cause, but the principle is clear: IUI is not repeated endlessly.

There are situations where IUI is unlikely to help and moving directly to IVF is more reasonable. When both tubes are blocked, IUI makes no sense at all, because egg and sperm cannot meet. When there is a significant male factor, IVF with ICSI offers far more. When there is advanced endometriosis, a low ovarian reserve, or when the woman is older, the time spent on IUI cycles can cost more than it gives.

This is where a full assessment before treatment makes the difference. A check of the tubes, a semen analysis and an assessment of the reserve at the start show whether IUI is a real chance or only a delay before IVF. Starting with the right tool saves months and disappointment.

In a 28-year-old with unexplained infertility, a few IUI cycles are a reasonable use of time, because reserve and egg quality are not changing quickly. In a 38-year-old, the same number of cycles can cost a year, and that year weighs heavily on the chance of IVF later. Many guidelines therefore recommend moving to IVF sooner over 35–38, or even starting with it.

Moving to IVF is not failure, nor a sign that 'everything is worse'. It is simply choosing the tool that fits the situation. An honest conversation from the start, stating clearly how many IUI cycles make sense and what the next step is, gives the couple control over their time and avoids the feeling of lost years.