Former president Donald Trump says that, if he wins a second term, he wants to make IVF treatment free for families, but did not detail how he would fund it or how it would work.

"I'm announcing today in a major statement that under the Trump administration, your government will pay for – or your insurance company will be mandated to pay for – all costs associated with IVF treatment," he said at an event in Michigan.

"Because we want more babies, to put it nicely."

IVF treatments are notoriously expensive, and can cost tens of thousands of dollars for a single round. Many women require multiple rounds and there is no guarantee of success.

Trump also said that, if he wins, families will be able to deduct expenses for caring for newborns from their taxes.

"We're pro-family," he said.

Trump first came out in favour of IVF in February after the Alabama state Supreme Court ruled that frozen embryos can be considered children under state law, briefly pausing treatment and sparking national backlash.

IVF can costs tens of thousands of dollars for medical appointments, medication and surgery, and is not covered by many health insurance plans.

Trump has in general been opposed to various kinds of federal mandates, and originally ran against the Affordable Care Act – also known as Obamacare – which included popular provisions like protections for people with pre-existing health conditions.

In a statement, Harris’ campaign said Trump shouldn't be believed.

Opinion polls show Trump has lost ground with women voters since  Harris became the Democratic candidate. Harris led Trump by 49 per cent to 36 per cent - or 13 percentage points - among women voters in a Reuters/Ipsos poll published this week, compared to her 9-point lead in polls conducted in July.

“Trump lies as much if not more than he breathes, but voters aren’t stupid," said Harris-Walz 2024 spokesperson Sarafina Chitika.

Trump accuses Harris and Biden of presiding over 'an economic reign of terror'. – AP

Trump made the IVF announcement during a campaign swing to Michigan and Wisconsin, states he is intensely focused on recapturing after he won them in 2016 but narrowly lost both states in 2020.

Trump's first stop was Alro Steel in Potterville, Michigan, near the state capital of Lansing, where he railed against the Biden administration over inflation.

"Kamala has made middle class life unaffordable and unliveable and I'm going to make America affordable again," he said.

Later, Trump traveled to La Crosse, Wisconsin, for a town hall moderated by former Representative Tulsi Gabbard, a former Democrat who endorsed the GOP nominee earlier this week.

Gabbard opened the town hall by talking about her own IVF journey, giving herself injections in airport bathrooms and the heartbreak of failed embryo transfers.

While the treatments ultimately didn't work for her, she applauded Trump's proposal.

“I can’t tell you how life-changing that would be for so many families," she said.

Trump speaks about his IVF treatment pledge at an event in La Crosse. – AP

It was his first visit to the state since the Republican National Convention in Milwaukee, which ended just days before Biden dropped out of the race and began after Trump survived an assassination attempt at a rally in Pennsylvania.

Michigan, Wisconsin and Pennsylvania, which Trump will visit again Friday, are part of the so-called “blue wall” bloc of northern industrial states that Democrats carried for two decades before Trump won them in 2016.