Delays in IVF treatments during the coronavirus lockdown will have a significant impact on successful births, according to new research.

Analysis of UK and US data found that across all ages of women, the lockdown will likely lead to a drop of 0.5% in the live birth rate following IVF treatment.

In the US this is equivalent to 734 fewer live births per year, according to researchers from the University of the West of England and the University of Glasgow.

IVF involves women being given an injection to stimulate her ovaries, after which eggs are removed from the ovaries and fertilised with sperm in a laboratory.

There is generally not much of a drop-off in a woman’s ability to have a baby after IVF between the ages of 26 and 35. After 35, this starts to fall quite dramatically, so every month counts

The embryo is then inserted into her uterus. Modern techniques mean doctors can also freeze some of her eggs to be used later to form an embryo that will be inserted into her womb.

Andrew Smith, a senior lecturer in statistics at UWE Bristol, said: “As IVF success is very sensitive to age, older women are less likely to have a successful outcome and live birth rates will be lower as a result.

“For a three-month shutdown in treatment, for instance, we predicted a 0.8% reduction in live birth rate, which is significant.

“There is generally not much of a drop-off in a woman’s ability to have a baby after IVF between the ages of 26 and 35.

“After 35, this starts to fall quite dramatically, so every month counts.”

Mr Smith said a woman aged 41 or 42 has a 12% chance of giving birth.

The findings are now being used by health providers and policy makers in determining how IVF treatment resumes after lockdown.

Professor Scott Nelson, from the University of Glasgow, said: “The work undertaken by Andrew Smith and colleagues on the impact of temporary cessation of fertility treatment provision has been critical to the decision making by healthcare providers to recommence treatments within the UK and globally.

“The Scottish Government and National Infertility Group have used the data and the differential age groups identified in the planning of the resumption of services and prioritisation of patients whose treatment was disrupted by the Covid-19 pandemic.”

Further research will be carried out to explore how the economic impact of the pandemic may affect IVF live birth success rates.

The paper, Population implications of cessation of IVF during the Covid-19 pandemic, is published in the journal Reproductive BioMedicine Online.