in keeping with the recommendations of the national confidential enquiry into patient outcome and death ( ncepod ) , a four - step classification system for the urgency of caesarean sections has been adopted in many uk obstetric units . in this scheme , grade 1 caesareans are performed when there is an immediate threat to the life of the woman or fetus , grade 2 when there is evidence of maternal or fetal compromise which is not immediately life threatening , and grade 3 when there is no maternal or fetal concern but early delivery is required . studies have demonstrated that for grade 1 and grade 2 caesareans , maternal and perinatal outcomes deteriorate measurably when the decision - to - delivery interval exceeds 75 minutes [ 36 ] , and it is reasonable to suppose that delivery in a much shorter time frame would be required to preserve perinatal health in the most urgent situations . the national institute for health and clinical excellence ( nice ) therefore recommends that in cases of confirmed or suspected acute fetal compromise , loosely equivalent to grade 1 procedures but also including some grade 2 procedures , delivery should be accomplished within 30 minutes where possible [ 1 , 7 , 8 ] . in clinical practice , adherence to this 30-minute timeframe often seems unachievable , or at least , is often not achieved [ 4 , 5 , 7 ] . in the national sentinel caesarean section audit ( 2001 ) only 63% of uk obstetric units were able to deliver even half of their most urgent cases within 30 minutes . it has been suggested that longer decision - to - delivery times arise because a multitude of tasks has to be completed in a coordinated fashion by a relatively large multidisciplinary team before the caesarean can take place , thus , staff shortages , poor training , and lack of appropriate facilities all have the potential to slow the process . a qualified midwife is a crucial member of the multidisciplinary team caring for any woman in need of a grade 1 or grade 2 caesarean , and this is part of the justification for uk maternity service policies stating that women in established labour should be provided with one - to - one midwifery care [ 1114 ] . the royal college of midwives annual survey of uk heads of midwifery ( 2005 ) revealed , however , that almost 75% of maternity units experience staffing shortages and can not provide this level of care [ 15 , 16 ] . in the present study , we set out to measure the impact of workload and midwifery staffing levels on the length of time taken to transfer a woman to the operating theatre and ultimately to deliver her baby by grade 1 or grade 2 caesarean . our secondary aims were to discover whether the time of day , the form of anaesthesia chosen for the procedure , the time spent in the operating theatre preparing the woman for her surgery , or the speed of surgery itself contributed significantly to delay in delivery of the baby . this was a 12-month - long prospective audit of clinical practice carried out on the delivery suite of a tertiary referral hospital in the north of england in the uk in 2006 . an audit proforma was completed by the obstetrician performing the surgery in conjunction with the attending midwife after every grade 1 and grade 2 caesarean performed during the study period . forms were collated by the research team within 72 hours of the operation , and missing data were added to the forms at that time when necessary . the primary indication for each procedure was recorded together with its designated grade , the time of decision , the time that the patient entered the operating theatre , the time that the operation was commenced , and the time that the baby was delivered . the form of anaesthesia used for each caesarean was also noted . finally , the total number of labouring women present on the delivery suite at the time of the caesarean was recorded , in addition to the number of qualified midwives present on the shift . scatter plots were then constructed to demonstrate the relationships between the decision - to - delivery interval and the time of day , the number of labouring women and the labouring woman  :  midwife ( lw  :  mw ) ratios on the delivery suite when the caesareans were being performed . chi - squared analyses were used to compare categorical variables , and analysis of variance was used to compare groups of continuous variables , with two tailed t - tests used to make more detailed comparisons where appropriate . in the study year , 5581 women gave birth at the unit including 414 women who were delivered by elective caesarean section . of the remaining 5167 women , 2620 gave birth between 08.31  hrs and 20.30  hrs , corresponding to junior doctors ' daytime delivery suite shifts , with on - site cover provided by one obstetric registrar , one obstetric senior house officer , one anaesthetic registrar , one consultant obstetrician , and one consultant anaesthetist . a further 2547 women gave birth between 20.31  hrs and 08.30  hrs , corresponding to junior doctors ' night - time delivery suite shifts , with on - site cover provided by two obstetric registrars , one obstetric senior house officer , and one anaesthetic registrar plus on - call and hence potentially off - site cover provided by one consultant obstetrician and one consultant anaesthetist . two obstetric operating theatres were available throughout the day and night , staffed by an anaesthetic nurse or an operating department assistant or practitioner . of these , 122 were grade 1 , 211 were grade 2 , and 422 were grade 3 procedures . the mean decision - to - delivery interval for grade 1 caesareans was 23 minutes ( sd 11 ) with 82.0% of babies being born within 30 minutes of the operation being requested and 99.2% being born within 75 minutes . for grade 2 caesareans , the mean decision - to - delivery interval was 32 minutes ( sd 13 ) with 45.0% of babies being born within 30 minutes of the operation being requested and 98.1% being born within 75 minutes . in all , the decision to perform a grade 1 caesarean was as likely to be made during the daytime as overnight ( 59/2620 versus 63/2547 , p = 0.104 ) and the individually measured indications for grade 1 procedures did not differ between the two time frames ( table 1 ) . by way of contrast , proportionately less grade 2 caesareans were performed during the day than during the night ( 97/2620 versus 114/2547 , p = 0.015 ) , and the greatest contributions to this difference came from a rise in the number of procedures being performed in response to a pathological ctg overnight without recourse to fetal blood sampling and a rise in procedures performed for nonprogressive labour in the second stage ( table 1 ) . figures 1 and 2 demonstrate the variation in the decision - to - delivery interval during different times of the day . in our series , the time at which the decision was made to perform either a grade 1 or a grade 2 caesarean had no measurable impact on the amount of time it then took to deliver the baby . for grade 1 caesareans the 30 minute cut - off was rarely breached until the number of laboring women on the delivery suit exceeded eight . beyond this point , the 30-minute time limit was frequently exceeded ( figure 3 ) . in keeping with this , when 1  :  1 care or better was being provided by midwives , 77/82 grade 1 caesareans were performed with a decision - to - delivery interval below 30-minutes but the time taken to deliver a baby increased significantly as the ratio deteriorated , so that only 22/40 babies were born within the 30 minute window when the lw  :  mw ratio was worse than 1  :  1 ( 1 , p < 0.001 ) ( figure 4 ) . for grade 2 caesareans , the decision - to - delivery interval was generally longer than for grade 1 procedures , and both the total number of women in active labour and the lw  :  mw ratio had a marked effect on the decision - to - delivery interval ( figures 5 and 6 ) . when 1  :  1 care or better was being provided by midwives , 90/168 grade 2 caesareans were performed with a decision - to - delivery interval below 30 minutes but the time taken to deliver a baby increased significantly as the lw  :  mw ratio deteriorated , so that only 5/43 babies were born within the 30-minute window when the ratio fell below 1  :  1 ( 1 , p < 0.001 ) . for grade 1 caesareans the time taken to transfer the patient to theatre was more than 15 minutes in only a minority of cases but a deteriorating lw  :  mw ratio still had a measurable negative impact on transfer times ( figure 7 ) . thus , when 1  :  1 care or better was being provided by midwives , transfer to theatre was achieved within 15 minutes for 81/82 grade 1 caesareans but was only achieved for 34/40 grade 1 caesareans when the ratio fell below 1  :  1 ( 1 , p < 0.001 ) . transfer of a patient to theatre for a grade 2 procedure was also influenced by the lw  :  mw ratio  when the ratio was 1  :  1 or better , transfer within 15 minutes was achieved in 155/168 cases whereas transfer within 15 minutes was only achieved in 29/43 cases when the lw  :  mw ratio was worse than 1  :  1 ( 1 , p < 0.001 ) ( figure 8) . 
 table 2 illustrates the forms of anaesthesia used in this case series . for grade 1 caesareans , general anaesthesia was more likely to be used in the daytime than overnight ( 31/59 versus 22/63 , p = 0.005 ) whereas spinal blockade , became the most commonly used anaesthetic overnight ( 17/59 versus 29/63 , p = 0.009 ) . comparing general anaesthesia , spinal blockade and epidural top - up , the choice of anaesthetic had a significant influence on the decision - to - delivery interval ( anova , f = 5.155 , p = 0.007 ) . we found that the mean decision - to - delivery interval for women having a grade 1 caesarean was 19.7 minutes ( sd 8.5 ) under general anaesthesia , compared to 27.0 minutes ( sd 8.2 ) under spinal blockade ( p < 0.001 ) . the decision - to - delivery interval was 26.0 minutes ( sd 18.7 ) when the caesarean was performed under an epidural top - up , which was usually administered prior to the woman leaving her delivery room for the operating theatre . for grade 2 caesareans , most women were delivered under regional blockade , and the choice of anaesthetic did not vary significantly with the time of day ( table 2 ) . the mean decision - to - delivery interval for women having a grade 2 caesarean was not influenced significantly by the choice of anaesthetic ( anova , f = 0.505 , p = 0.681 ) , with women having an epidural top - up being delivered in an average of 29.2 minutes ( sd 15.4 ) , women having general anaesthesia being delivered in 30.1 minutes ( sd 19.4 ) , and women having spinal blockade being delivered in 34.7 minutes ( sd 12.0 ) . for women having a grade 1 caesarean , the mean time span from arrival in theatre to the start of the operation was 19.1 minutes ( sd 9.6 ) but this time varied with the form of anaesthesia employed ( anova , f = 18.4 , p < 0.001 ) . if the caesarean was performed under general anaesthesia , the operation was commenced 14.4 minutes ( sd 6.0 ) after the woman 's arrival in theatre , which compared favourably to the mean time span of 24.6 minutes ( sd 9.6 ) if a spinal blockade was used ( t - test , p < 0.001 ) and to the mean time span of 20.0 minutes ( sd 11.4 ) if an epidural top - up had been administered ( t - test , p = 0.032 ) . figure 9 demonstrates the relationship of the lw  :  mw ratio to the time taken from arrival of the patient in the operating theatre until commencement of the operation for grade 1 procedures . although the midwife performs a number of essential steps in the preparation of a woman for caesarean in theatre , the lw  :  mw ratio had no discernible bearing on this time interval .   for women having a grade 2 caesarean , the mean time span from arrival in theatre to the start of the operation was 20.4 minutes ( sd 8.6 ) , which was not significantly different to the time span for grade 1 procedures ( t - test , p = 0.201 ) . if a general anaesthetic was administered , this phase lasted 18.2 minutes ( sd 14.9 ) compared to 21.1 minutes ( sd 6.5 ) if a spinal block was employed and 19.9 minutes ( sd 10.3 ) if an epidural top - up had been given . analysis of variance revealed no statistically significant difference in performance between these forms of anaesthesia ( anova , f = 1.10 , p = 0.335 ) . figure 10 demonstrates the relationship of the lw  :  mw ratio to the time take from arrival of the patient in the operating theatre until commencement of the operation for grade 2 procedures . again , the lw  :  mw ratio had no discernible bearing on this time interval . the time taken from skin incision to the delivery of the baby was 3.3 minutes ( sd 1.9 ) for grade 1 caesareans and 4.7 minutes ( sd 3.1 ) for grade 2 caesareans , giving an average saving of 1 minute and 24 seconds for the more urgent procedures ( p < 0.001 ) . more than one in five uk babies is born by caesarean and of these approximately 63% are emergency procedures . in our series , of the 755 emergency caesareans identified , 422 were grade 3 procedures with no evidence of maternal or fetal compromise . this paper focuses on grade 1 and 2 procedures , providing greater detail than what has previously been published about the timing of events between the decision to deliver a baby in such circumstances and the eventual birth of the baby . we have shown that for both grade 1 and grade 2 caesareans , delivery is most likely to be achieved within 30 minutes if the complement of qualified midwives on a delivery suite is sufficient to allow one - to - one care to be provided to women in active labour . more specifically , failure to provide this level of care hinders the woman 's transfer to the operating theatre but , once the woman has arrived in theatre , the labouring woman to midwife ratio has no further bearing on the delivery time of the baby . the present study did not investigate why poor lw  :  mw ratios should delay transfer of a woman to theatre for her caesarean , but a multitude of tasks must be performed by the midwife before theatre transfer is possible , as most theatre check lists will attest . any  away - time  that the midwife has from her preoperative patient , for example , to provide clinical care to another woman or to arrange for a colleague to provide that care , is therefore likely to delay theatre transfer . this phenomenon may be most relevant to the performance of grade 1 caesareans , when individual minutes rather than tens of minutes can be crucial to the well - being of a hypoxic fetus . commendably , however , for grade 1 caesareans the effect of poor lw  :  wm ratios appears to be relatively small , possibly because midwifery and other staff prioritise care in order to achieve rapid transfer of the woman to theatre , preparation of the woman for surgery in the operating theatre , then actual delivery of the baby . as a result , in the present study , relatively few women having a grade 1 caesarean were delivered beyond the 30-minute benchmark . for grade 2 caesareans , there was a clearer lengthening of the time that it took to transfer a woman to the operating theatre when lw  :  mw ratios deteriorated and , hence , a lengthening of the decision - to - delivery interval . this is of concern because although grade 2 caesareans are not performed when the life of the mother or fetus is in imminent danger , they are nonetheless performed because of evidence of maternal or fetal ( usually fetal ) compromise . it is logical to deduce that any systematic , unnecessary delay in achieving delivery of the baby for this population will cause clinical outcomes to deteriorate , an effect which we have now set out to measure with further detailed audit work . the time spanning arrival of a woman in theatre and the start of her operation did not differ between grade 1 and grade 2 caesareans in this study , nor with the lw  :  mw ratios on the delivery suite . this may have been because women in theatre are generally attended by a full complement of midwifery , medical , nursing , and ancillary staff whatever the level of urgency involved . we did , however , find that the provision of a general anaesthetic rather than a regional blockade shortened the decision - to - delivery time for grade 1 procedures , largely by minimising delay in the operating theatre itself . the same effect was not seen when grade 2 caesareans were being performed , highlighting the fact that this was an observational study rather than a randomised , interventional study ; for grade 2 caesareans , it seems likely that women being delivered under general anaesthesia were in some physical or psychological way dissimilar to women delivered with a regional blockade whereas , for grade 1 caesareans , such considerations may have been circumvented .   like most other obstetric units in the uk , the pattern of medical staffing during the daytime differed from that seen overnight on the study site . overnight , the delivery suite gained the services of an extra obstetric registrar but the consultant obstetrician and consultant anaesthetist provided on - call rather than on - site cover . the data suggest that either because of this change or because of some other unmeasured factor , clinical decision - making changed overnight . obstetrically , little difference was seen in the numbers of grade 1 caesareans performed or the reasons that they were performed . in contrast , an increase in the proportion of women having a grade 2 caesarean section was seen overnight , largely because of an increase in the number of procedures being performed for ctg abnormalities ( without use of an fbs ) or because of nonprogressive labour in the second stage . the possibility is that the presence of a consultant obstetrician on - site overnight might redress this imbalance , but a well - constructed intervention study would be required to prove the benefit . it seems likely , however , that the drive towards 24-hour on - site cover from consultant obstetricians in busy uk obstetric units will continue without such data ever being generated . in anaesthetic practice , too , there were measurable differences between daytime and night time care . in particular , a more liberal use of general anaesthesia for grade 1 caesareans was seen in the daytime , possibly because of the increased presence of consultant anaesthetists , although other unmeasured factors such as variations in the case mix could also have influenced the results of this study . as such , the findings of the study may not be applicable to smaller obstetric units ,  stand - alone  midwifery led units or  alongside  midwifery led units , which deal with different case mixes and which may face quite different organisational challenges . finally , this study focussed upon the timing of events during grade 1 and grade 2 caesareans and the influence that a number of factors could have on the various components of the decision - to - delivery interval . any conclusions drawn about the relative benefits of , for example , providing one - to - one midwifery care to labouring women and providing 24 hour on - site cover from consultant obstetricians and consultant anaesthetists would be speculative . the work does , nevertheless , provide greater detail than what has previously been published about the events leading to delivery by grade 1 or grade 2 caesarean , and it highlights areas of clinical practice worthy of more detailed appraisal .
rcog / nice guidelines recommend that , for fetal compromise in labour , delivery should be accomplished ideally within 30 minutes . in this study , we investigated the factors which affect the decision - to - delivery ( dd ) intervals for emergency caesareans . to achieve this , 
 prospective data were collected for all grade 1 and 2 caesareans performed on a busy labour ward over 12  months . 
 we found that the ratio of labouring women to midwives had a significant effect on the dd intervals , which were significantly prolonged when 1  :  1 care was not provided ( p < 0.001 ) . 
 the observed effect resulted exclusively from a prolonged transfer time to theatre . 
 general anesthesia use shortened the dd interval for grade 1 caesareans ( p < 0.001 ) and was more likely to be used during the day shift ( p < 0.009 ) . 
 we conclude that midwifery staffing levels and the form of anaesthesia employed influence on dd intervals for the most urgent caesarean sections .