Almost a fifth of the most critically ill coronavirus patients in England in recent months were unvaccinated pregnant women, health officials said as they urged expectant mothers to get their jabs.

NHS England said that, between July 1 and September 30, 17% of Covid patients receiving treatment through a special lung-bypass machine were mothers-to-be who had not had their first dose of a Covid-19 vaccine.

The organisation said data also showed that pregnant women accounted for 32% of all females aged between 16 and 49 in intensive care on extracorporeal membrane oxygenation (ECMO) - used when a patient's lungs are so damaged by Covid that a ventilator cannot maintain oxygen levels.

NHS England said this figure has risen from 6% at the beginning of the pandemic in March 2020.

England's chief midwife, Jacqueline Dunkley-Bent, said the data is "another stark reminder that the Covid-19 jab can keep you, your baby and your loved ones safe and out of hospital".

But the National Childbirth Trust (NCT) said the statistics are a "damning indictment of the lack of attention given to this vulnerable group as restrictions have eased".

NHS England said data from more than 100,000 Covid vaccinations in pregnancy in England and Scotland, and a further 160,000 in the US, show there has been no subsequent harm to the foetus or infant.

Mother-to-be Claire Bromley spent almost a month in hospital with coronavirus and said she feels the risk of being unjabbed "far outweighs any doubts" about getting a vaccination.

The 33-year-old, who had not been vaccinated, was admitted to her local hospital in Kent with breathing difficulties just a few days after testing positive for the virus, and was then put on a ventilator while in a medically induced coma.

Wandsworth Times: Claire Bromley - PAClaire Bromley - PA

When her condition deteriorated, medics thought she might need an emergency C-section just 26 weeks into her pregnancy and she was transferred to another hospital in London.

But her condition improved and she was allowed home in early August, almost a month after first being admitted, and is now recovering with her husband and their unborn child, who is doing well.

She said: "I completely understand the hesitation not to get vaccinated when you are growing a child inside you, and, after experiencing two miscarriages before the pandemic, the fear of being pregnant again with the worry of Covid was sending my anxiety through the roof.

"But, after what happened, I can honestly say that the risk of not having the Covid vaccine far outweighs any doubts about having it."

Dr Edward Morris, president of the Royal College of Obstetricians and Gynaecologists, said medics understand women's concerns but want to offer reassurance that the vaccine is safe.

He said the "disproportionate" number of unvaccinated pregnant women in intensive care shows there is a "significant risk of severe illness from Covid-19 in pregnancy".

He said: "We are urgently calling for all pregnant women to come forward for their vaccinations.

"There is robust evidence showing that the vaccine is the most effective way to protect both mother and baby against the possibility of severe illness from Covid-19.

"The disproportionate number of unvaccinated pregnant women in intensive care demonstrates that there is a significant risk of severe illness from Covid-19 in pregnancy.

"We do understand women's concerns about having the vaccine in pregnancy, and we want to reassure women that there is no link between having the vaccine and an increased risk of miscarriage, premature birth, or stillbirth."

Public Health England data shows more than 81,000 pregnant women have received the first dose of a Covid vaccine, and around 65,000 have received their second dose, NHS England said.

Addressing mothers-to be, Ms Dunkley-Bent said: "You can receive vaccination at any time in pregnancy, but the risks that unvaccinated pregnant women face of becoming severely unwell if they catch Covid-19 show exactly why we advise you to do so as soon as possible."

Sarah McMullen, director of impact and engagement at the NCT, said: "We've been extremely disappointed to hear of so much misinformation and confusion about the vaccination programme and so little focus on what's needed to keep vulnerable groups safe as restrictions have eased.

"We strongly encourage pregnant women to consider having the Covid-19 vaccination and have information on our website to help them make a decision."

Health Secretary Sajid Javid added his voice to calls encouraging pregnant women to have the jab, saying the latest figures on those in hospital are "desperately sad" and that vaccines will give "significant protection".