Catastrophic failings in maternity services are back in the news in the UK with the publication of the truly shocking final Ockenden Report into adverse events at Nottingham University Hospitals NHS Trust. It found that more than 500 mothers and babies suffered avoidable harm or died.For me, one of the clear issues of systemic failure in the report is exactly the point I expressed grave concerns about just last month in correspondence relating to the recently published National Clinical Practice Guidelines on Labour. The guidelines were issued by the HSE and endorsed by the Institute of Obstetricians and Gynaecologists One element of the guidelines relating to the definition and management of the early stages of labour is, in my view, so deficient as it stands that it risks introducing into Irish maternity services exactly the problems that led to unnecessary deaths and injury in the UK. This issue is the retrograde and harmful concept of a “latent phase” of labour. This is expressed in the clinically meaningless, but highly dangerous, approach that a woman is “not in established labour” until her cervix is 4cm dilated. In fact, the course of labour is properly defined as the progressive dilation of a woman’s cervix from 0cm to 10cm. The dangerous concept of a latent phase of labour dates from a study of just 100 women in a hospital in New York in the 1950s who had their first babies with no intervention. The erroneous conclusion was that if nature was left to take its course, especially in the early stages of labour, all would be well. As the Ockenden and other reports make clear in devastating detail, this approach can have catastrophic consequences. In practice, the concept of a latent phase in labour means women who are experiencing painful contractions at home or in hospital antenatal wards are not being transferred to the labour ward because they have not met the 4cm dilation test. Even more dangerously, the new HSE guidelines advise that a woman can be sent home until she reaches this point. The guidelines are silent, however, on how a woman at home is expected to know she has reached 4cm dilation. Clearly she cannot do this, so the labour is progressing – or not – without medical oversight.The deaths of two babies detailed in the Ockenden Reports provide tragic case studies of this issue.Sarah Hawkins was two days past her due date with her first baby on April 13th 2016 when she went into Nottingham Hospital with strong contractions and having had “a show” (the blood-stained plug of mucus that discharges when the cervix has started to efface). She was now clearly in labour. The midwife who examined Sarah found her cervix 2cm-3cm dilated with membranes intact, deemed her to be in the “latent phase” of labour, discharged her home and made an appointment for review one week later. Over the course of the next few days, Sarah and her husband Jack contacted the hospital repeatedly, only to be told she was “not in established labour” or that she was in the latent phase. At around 3am on April 17th, she was finally advised to come into hospital where she was examined and found to be 9cm-10cm dilated. Sarah’s daughter Harriet was delivered more than 10 hours later. She was dead. The total duration of labour had been more than four days.Baby Thomas died 34 minutes after his birth at Shrewsbury and Telford Hospital Trust in 2009. His mother spent more than 12 hours on the midwife-led unit deemed as being in the latent phase of labour. It was her second pregnancy and labour. She was then transferred to the consultant-led unit where she spent a further 19 hours until, at 5cm dilated, she was transferred to the labour ward and was only infrequently monitored. In the hours before birth, examinations showed signs of obstructed labour. She was eventually delivered by Caesarean section after about 42 hours of labour, 10 at full dilation, by which point her uterus had, unsurprisingly, ruptured. The “latent phase” approach was a critical contributor to the mismanaged labour, which was astonishingly and unacceptably long.When I was master of the National Maternity Hospital in the 1990s, my practice every day was to review personally every labour of the previous 24 hours. I analysed the course of at least 42,000 labours over the seven years of my term. Over the past couple of decades, I have led several HSE reviews into adverse clinical outcomes in pregnancy, acted as a coroner’s witness in several inquests into the deaths of mothers and babies, and I continue to encounter catastrophic outcomes in my work as an expert witness in medical legal cases relating to pregnancy and birth. Deficiencies in the care of women in labour linked to “latent phase” mismanagement have featured all too often.This experience is what underpins my warning that the concept of a “latent” or “not established” phase of labour must be excised from obstetric care. It is a throwback to the 1950s and has no place in modern practice. Women’s labours progress at different rates depending on many circumstances, including whether they are having a first or subsequent baby. The safest model of obstetric care is when women are carefully monitored by experienced midwives operating in integrated teams with obstetrician colleagues. There must be no silos of competing midwifery or consultant-led units, but an entirely collaborative, single-tier approach to woman-centred care.Our National Clinical Practice Guidelines on Labour should be revised by the HSE without delay. We must not see the problems experienced in Nottingham becoming embedded in obstetric practice here.Peter Boylan is a former master of the National Maternity Hospital