A father who has fought for a change in the law so that bereaved parents can look after their babies after the death of a partner will tell his son he can make the “impossible” happen after new rights for workers are laid before parliament on Monday.

Aaron Horsey was shocked when he discovered he had no right to take leave to look after his newborn son, after his wife, Bernadette, 31, died while giving birth at Royal Derby hospital.

Because Horsey, a clinical trial manager, had worked for his company for less than nine months, he did not have the automatic right to paternity leave or parental leave, despite being left in sole care of his son.

A little over three years after telling the Guardian of his fight to ensure that other fathers and partners would not have to go through the same emotional trauma, he said new paternity leave for bereaved partners – which will give up to 52 weeks of leave for those who lose their partner before their child’s first birthday – meant other grieving parents would have “a clear route for support at one of the most difficult moments imaginable”.

Measures secured under Labour’s employment rights bill to give day-one rights to paternity leave and paid parental leave to working parents will also be presented to parliament, after the government made a number of concessions to secure its passage through the House of Lords in December. The new rights affecting paternity and parental leave will come into effect in April.

Seeing the legislative journey of the Paternity Leave (Bereavement) Act– which started as an urgent conversation between Horsey, carrying his three-week-old son, and his then MP, Darren Henry, the Conservative member for Broxtowe in Nottinghamshire – had left Horsey with mixed emotions. “I’m proud that something good has come from a very difficult experience and I’m glad that this particular worry won’t need to affect anyone in future and they can simply have the time they need without delay,” he said.

Asked what he would say to his son about the change in the law, which received cross-party support and was introduced with a private member’s bill by Chris Elmore, the Labour MP for Bridgend, Horsey said: “I’ll tell Tim that sometimes challenges arise and they might seem impossible. We can always choose what to do next. If something needs to be changed, it’s always worth trying to – even if it takes a long time to get there.”

The legislation, which amended the Employment Rights Act 1996, became law on the last day of parliament in 2024 and applies in England, Scotland and Wales. Although it does not apply in Northern Ireland, Horsey is hopeful that the country will benefit from the change in the future.

Reflecting on the change, he said he suspected his wife would have been more proud of his son “growing into a kind and curious person” than the legislation, but added: “She was always very focused on fairness and kindness, and I think she’d be glad that what happened to us has led to something that will help other families.”

A government spokesperson said the recently passed Employment Rights Act 2025, which amends the 1996 act, would see an additional 32,000 fathers a year be able to access paternity leave immediately. Campaigners have argued that new fathers have been betrayed by the act, after it emerged that a promised “day-one” right to paternity leave would not include the day-one right to statutory pay.

Keir Starmer said the changes meant new parents would be able to take time off when they had a child, and no one would be forced to work while ill just to make ends meet. “This is about giving working families the support they need to balance work, health and the cost of living,” the prime minister said.

The TUC general secretary, Paul Nowak, said the act would “deliver vital commonsense reforms for millions of people across the country – including sick pay for all workers and better leave for parents” and bring Britain into line with other countries.