IVF works more quickly than IUI for patients with unexplained infertility

IVF offers a faster route to parenthood than intrauterine insemination (IUI) for couples with unexplained infertility, according to new research.

Researchers at the University of Auckland, New Zealand, enrolled 737 couples across six fertility clinics who either received up to four rounds of IUI or one complete cycle of IVF during the first stage of treatment. Among the 585 couples assessed in this stage, 55 percent of those given IVF went on to have a baby compared with 31 percent of those given IUI.

'We found that IVF resulted in more live births, so approximately one in two couples would end up with a baby after doing one cycle of IVF, compared to one in three with IUI,' said Dr Lucy Prentice, who led the research published in the New England Journal of Medicine.

Couples who had not yet had a baby were offered further IVF in the second study phase. Both groups had similar live birth rates after 20 months, at 71 percent in the IVF group compared with 70 percent in the IUI group.

As well as having a baby approximately two months sooner on average, 68 percent of the IVF group had frozen embryos remaining at the end of the trial compared with 40 percent of the IUI group.

However, IVF also carried a greater risk, with serious complications occurring in 14 of the IVF couples compared with six in the IUI group.

'If couples want to take a slower, less invasive approach and start with IUI before progressing to IVF, that doesn't negatively impact their chance of having a baby within two years,' said Dr Prentice. 'That means the choice can be guided by the couple's preferences.'

Infertility affects approximately one in six couples and up to a third of cases have no identifiable cause. Guidelines published by the World Health Organisation and the American Society for Reproductive Medicine recommend trying IUI before IVF for unexplained infertility. IUI is often favoured as it is cheaper and less invasive, with no need for egg collection or laboratory fertilisation. Instead, it involves stimulating a woman's ovaries using fertility drugs before placing sperm directly into the uterus.

In the UK, the National Institute for Health and Care Excellence removed IUI as a recommended option for unexplained infertility in 2013 (see BioNews 810). It then updated its Guideline in March 2026 to recommend considering up to four rounds of IUI before IVF.

The researchers highlight that the evidence supporting international recommendations is limited. They also emphasised that treatment choice should consider cost, patient preference and safety, and plan to carry out additional analysis of cost-effectiveness and acceptability.