The NHS's maternity care review has been thrown into further controversy after it emerged that one of its leading experts resigned over concerns it had 'whitewashed' the issue of so-called 'natural birth ideology'.The National Maternity and Neonatal Investigation (NNMI), chaired by Baroness Amos, concluded that women and babies have been put at risk by a system that is 'not set up to deliver consistently safe, high-quality and compassionate care'. In a wide range of troubling revelations, the damning review found that maternity units are 'not fit for purpose' and that filthy, crumbling hospitals had left mothers suffering unsafe and undignified care.Harrowingly, it also uncovered that a lack of bereavement suites means families are often told devastating news in general waiting areas and forced to carry their dead babies past rows of happy new parents.And now, it has been revealed that Dr Bill Kirkup, one of the UK's leading maternity experts, quit his role as an adviser for the review after concerns it had downplayed how 'normal birth ideology' had played a role in avoidable deaths and injuries. The term - also known as physiological birth - refers to labour and vaginal delivery with little-to-no medical interventions. This means labour begins without induction, a process where the uterus is stimulated to start the process of childbirth, and no pain relief - like epidural nerve injections - are given. Normal birth ideology also claims that caesarean sections (C-sections) - the surgical removal of the baby directly from the abdomen - should be avoided unless absolutely necessary. The NHS's maternity care review has been thrown into further controversyStudies have suggested that normal vaginal births can improve women's birth experiences, support earlier breastfeeding and encourage a strong bond between mother and baby. But critics say the process unnecessarily raises risk, pointing to references in previous maternity scandals where some women were found to have been denied C-sections, sometimes with fatal consequences.The Royal College of Midwives ran a campaign from 2005 until 2017 for women to give birth this way, saying it aimed to encourage normal births while ensuring women who required or chose assisted births did not feel they had 'failed'.In the UK, more than half of women having a baby today use medical intervention. Experts say the rise stems from births becoming more complicated in recent years - partly because more older and obese women are having babies.It has been claimed that, prior to his resignation, Dr Kirkup and fellow experts in the field penned a section of the review warning that the 'normal birth ideology' posed a risk to patient safety. However, this was omitted from the final report.An annex to the review claims Dr Kirkup's resignation stemmed from a disagreement over the 'specific wording' of this section. But it is reported by the Health Service Journal (HSJ) that he resigned over the findings rather than how it was framed.It is claimed he wanted the review to dig deeper into the risks of 'normal birth ideology' than Baroness Amos wished. It is not known how many deaths or complications were resulted from 'normal' birthing.Former health secretary Jeremy Hunt said he was 'deeply worried' by Dr Kirkup's resignation.A letter from Baroness Amos seen by the HSJ, reads: 'Dr Bill Kirkup has decided to step down from his role as one of the expert advisers to the NMNI.'This was following discussions regarding the wording of the conclusions relating to normal birth ideology in the final report, where we were not able to reach agreement.'In an address to families involved in the review, she added: 'I am very grateful for Bill's experience and expertise throughout the investigation and as we have drafted the final report and recommendations, which are stronger as a result of his input.' Mr Hunt wrote on X: 'Deeply worried to hear that Dr Bill Kirkup, author of the Morecambe Bay and East Kent maternity reports, resigned from the Amos review because he thought it whitewashed the issue of 'normal births'. 'Only last week [Donna Ockenden, chair of the independent review of maternity services at Nottingham University Hospitals NHS Trust] - rightly - said the issue 'caused long-term harm'.'The investigation into maternity care was launched by Wes Streeting, the former health secretary, who resigned in May, in a bid to learn from mistakes exposed by a series of maternity scandals across England.Baroness Amos (left) says Dr Bill Kirkup (right) quit the National Maternity and Neonatal Investigation after concerns it had watered down how 'normal birth ideology' played a role in unavoidable deaths and injuriesIt was published just days after a review into Nottingham University Hospitals NHS Trust found 520 cases in which mothers and babies suffered potentially avoidable harm or death as a result of poor care. The new review, published on Monday, heard from 450 families, received 10,500 responses to a call for evidence, and gathered evidence from 9,000 staff. Investigators also visited 12 NHS trusts.Pregnant women described blood-stained toilets and showers, dirty beds and wards infested with insects and mould.Midwives, meanwhile, warned that leaks, faulty equipment and other 'safety hazards' distracted them from their work, and a lack of beds and cots in units impacted decision-making.One woman told investigators: 'The postnatal ward was dirty. My partner had to bring in Dettol. There was blood. It was awful.'In another case, a parent said: 'Can you imagine how I felt having to carry my dead son past all those happy parents with their babies... we should have been in a different part of the hospital.'The review concluded that the NHS had been inflicting avoidable harm, ignoring women's concerns and covered up mistakes despite years of inquiries, reviews and hundreds of previous recommendations. It added that the maternity system must now be redesigned to improve safety and reflect the fact that mothers are increasingly older and more likely to require C-sections. Lady Amos said: 'Words cannot describe the pain, suffering and trauma I saw and heard time and time again when talking to women and families about their experiences of maternal and neonatal care in England.'Anticipation and joy turned into pain, distress and trauma. 'There is absolutely no justification for the tragic cases of unsafe care and avoidable harm we continue to see in England. Nor is it acceptable that so many women and families experience a poor response and lack of accountability when something goes wrong.'The Department of Health said it would appoint a commissioner in line with the report's recommendations and pledged £41million to improve maternity safety.James Murray, the current health secretary, said: 'For too long women, babies and families have been failed by a system that didn't listen. Their stories are heartbreaking and demand action.'I am grateful to Baroness Amos for her work on this landmark review, which is a turning point. Appointing the UK's first ever Maternity and Neonatal Commissioner will drive lasting change and make sure women and families are never ignored again.'