Maternity wards in England were forced to close their doors 382 times in 2016, according to new figures that have triggered claims of women being “pushed from pillar to post in the throes of labour”.

Campaigners warned that expectant mothers could be left in fear of giving birth at the roadside after a wide-reaching freedom of information request found a 70% increase in the number of maternity ward closures over two years.

Research by the Labour party found that 42 hospital trusts had been forced to shut their doors at some point over the last year – 44% of those who responded – with many blaming staff shortages and bed and cot capacity.

Fourteen of them admitted they had shut down more than 10 times, with some taking more than 24 hours to reopen.

In total, there were 382 occasions when units had to close in 2016. This figure is slightly higher than the 375 occasions from the year before, and an almost 70% increase on the 225 in 2014.

The findings triggered an immediate response from campaign groups, who pointed to the government’s own maternity policy, which says there should be enough midwives to prevent this happening.

Elizabeth Duff, senior policy adviser at NCT, the UK’s largest charity for parents, said: “It’s appalling that a shortage of midwives and equipment means that so many units have been closed time and again so that pregnant women are pushed from pillar to post in the throes of labour.”

She warned that a single closure at short notice could result in a woman in advanced labour being told to travel miles to another hospital, “leaving them anxious and frightened about having their baby in a car or by the roadside”.

The shadow health secretary, Jonathan Ashworth, described it as “staggering that almost half” of all units had closed down at some point. “These findings show the devastating impact that Tory underfunding is having for mothers and children across the country … The uncertainty for so many women just when they need the NHS most is unthinkable,” he said.

“Under this government, maternity units are understaffed and under pressure. It’s shameful that pregnant women are being turned away due to staff shortages, and shortages of beds and cots in maternity units.”

The FoI request – covering data from 2014, 2015 and 2016 – received responses from 96 out of 136 NHS trusts.

Trusts reporting maternity closures cited bed capacity problems and high activity. St Helens and Knowsley teaching hospitals NHS trust closed down for more than 30 hours during one period; Bradford teaching hospitals NHS foundation trust shut 10 times; the maternity unit at Royal Berkshire NHS foundation trust had to close 30 times due to “insufficient midwifery staffing for workload”; Mid Yorkshire Hospitals NHS trust said the need to “maintain safety and staffing levels” forced it to close five times, including once for 14.5 hours. Other trusts cited a lack of cots.

Labour highlighted a warning from the Royal College of Midwives earlier this year that maternity services were “reaching crisis point” due to a shortage of 3,500 midwives. The college also warned that more than a third of the NHS’s midwives were nearing retirement age.

Prof Mary-Ann Lumsden, vice president of the Royal College of Obstetricians and Gynaecologists (RCOG), said the UK remained a safe place to give birth. “However, the pressures on maternity services are growing, which could compromise the experience for women and their families. Stretched and understaffed services also affect the quality of care provided to both mothers and babies,” she said.

“Unit closures may be due to insufficient midwifery, obstetric or paediatric staff, as well as inadequate capacity. If the UK governments are serious about improving the safety of maternity services, these staffing and capacity issues must be addressed as a matter of urgency.”

Lumsden said it could be distressing for a woman in labour being turned away from a hospital, although stressed that closures were “relatively unusual”. She said units worked as part of a network that could help provide alternative care at a nearby hospital – “though this is less than ideal”.

The RCOG has produced recommendations on how units can have medical staff available at all times in the face of changed working patterns, reduced trainee availability and financial constraints.

The Department of Health said: “Patients should be reassured we continue to have enough midwives in the NHS. Temporary closures in NHS maternity units are well rehearsed safety measures which we expect trusts to use to safely manage peaks in admissions.

“To use these figures as an indication of safe staffing issues, particularly when a number of them could have been for a matter of hours, is misleading because maternity services are unable to plan the exact time and place of birth for all women in their care.”