A graphic Labour pamphlet warns voters in Copeland that a Tory victory in the by-election will “cost mums their children” in an open letter aimed at highlighting the risks of NHS cuts in the constituency.

The handwritten letter in support of Labour candidate Gillian Troughton, a St John ambulance driver and former hospital doctor, is from local mother Paula Townsley. The leaflet is the second posted through letterboxes by Labour activists to contain dire warnings about the closures of maternity services at West Cumberland hospital.

Townsley’s letter describes how she gave birth to twins who were 15 weeks premature at West Cumberland hospital, but one of her sons did not survive. Expectant mothers will need to travel more than 40 miles to give birth in Carlisle if the maternity services in the area are closed.

Kevin Schofield (@PolhomeEditor) Labour really upping the ante in Copeland - a Tory win "will cost mums their children". pic.twitter.com/VeOtGqSXCd

“If I had to travel to Carlisle, I would have lost them both,” she wrote. “West Cumberland hospital has been a lifeline for me and my family.

“The staff still remember my son when he goes in now. They call him the miracle baby. If the Tories are voted in they’ll take it as a green light for the local NHS closures. Their cost-cutting will cost mums their children.

“As a mum to a miracle son, I’m asking you to please vote Labour in our local NHS services on 23 February. It’s only 10 minutes to go to vote for Labour’s Gillian Troughton, but it could save so much.”

The previous Labour byelection leaflet also included a quote from unnamed midwives, warning “mothers will die, babies will die, babies will be brain-damaged”.

Chris Whiteside, who has previously stood for the Conservatives in the seat, said: “I don’t know whether this will help Labour win the Copeland byelection but their tactics on the hospital deserve to lose.”

Labour’s campaign was given a boost on Thursday after negative headlines in the local paper about Theresa May’s visit to the constituency, where she repeatedly refused to answer questions on whether she would back the maternity cuts or over whether the government would underwrite the Moorside nuclear plant, after the Japanese company Toshiba pulled out of the project.

Canvassing is believed to show that Labour has a vote retention in some parts of the constituency as low as 70%.

Few Labour voters are switching directly to the Tories, one Copeland campaign source said, but many have told the party they are opting to stay at home. The party is said to be relying on legwork from the GMB union on the day of the byelection to persuade Sellafield workers to turn out and vote Labour.

Corbyn has confirmed he does not intend to campaign in the constituency again before polling day on 23 February.

The Tory campaign has been hinged on support for nuclear power and the Sellafield plant, a major employer in the area, highlighting Labour leader Jeremy Corbyn’s opposition to nuclear power. Tory leaflets distributed in the constituency feature a quote from Corbyn saying: “I say no nuclear power, decommission the stations we’ve got.”