Today I’m going to investigate the claim made by NCB advocates that epidurals slow down labour. I use the term “today” loosely, I have a young infant and he hasn’t quite figured out how to be self-sufficient yet.
- epidurals prolong the first stage of labour compared to opioids for analgesia – but only by 30 minutes on average
- placement of an epidural may increase or decrease contractions depending on individual factors (maternal position after placement, use of fluid bolus, amount of circulating maternal adrenaline)
- epidurals prolong the second stage of labour compared to opioids for analgesia – but only by 15 minutes on average
- epidurals increase the risk of instrumental vaginal delivery (OR 1.42) but the effect is dose-dependent and is not present if 0.0625% bupivacaine is used (note, most modern units use 0.06% or 0.08% as their standard labour epidural solutions).
- epidurals have no effect on the overall cesarean delivery rate (OR 1.04)
- you can have a neuraxial technique (epidural or combined spinal-epidural) for pain relief/ analgesia at any time during your labour
It turns out that length of labour has been a secondary outcome in quite a few randomized controlled studies on epidural analgesia in labour. It may seem like a simple problem but the more you think about it, the more difficulties present themselves. Firstly, how do you define the start of labour when so many different labour patterns are variations of normal? Secondly, it might seem easy to define the end of the first stage as the time when the cervix has reached 10 cm dilation…but some of the studies didn’t mandate regular cervical exams and those that did chose intervals of roughly 2 hours. A cervical exam for complete dilatation is generally done when a woman feels “pushy” or complains of rectal pressure. With a good epidural on board, it is possible that a mom might be fully dilated for a period of time before her sensations prompt caregivers to perform a cervical exam. RCTs looking at this problem have generally used systemic opioids as the control group on the grounds that it is unethical to deny women pain relief in labour. We have very little data on how opioids affect the progress of labour so how can you generalize the results to births where the women use no analgesics at all? Most of these trials have high “cross-over,” to quote the authors of one study in which 245 women were randomized to epidurals or opioids (16):
“Of 245 selected patients, 43 had to be removed from the trial afer labor ensued…Most of the patients removed from the non-epidural group were apparently experiencing severe pain; they were usually primigravidae whose baby presenting in the occipito-posterior position…The majority of patients removed from the epidural group were apparently normal and usually multigravidas; their labours were so rapid it was not possible to arrange for an epidural block.”
In addition, you can’t blind caregivers to the type of analgesia used so you can’t remove the possibility that caregiver biases towards women receiving opioids or with epidurals will alter how labour is managed. The women who agree to participate in the trial themselves may not be representative of women in general. How many women do you know would be happy to be randomized to an epidural or no epidural? Most women don’t want that choice taken from them.
Then there is the problem of causation versus association. This seems to confuse a lot of people but it’s really a simple exercise in Aristotelian logic: all mountains are big…elephants are big…ergo elephants are mountains. Women with epidurals use more pitocin….pitocin use is associated with a higher rate of C/S…ergo epidurals cause stalled labour and eventually C/S. Both logical trains in this paragraph have gone severely off the tracks. No one over the age of 4 would repeat the first…and I think even most 4 year olds would find that statement quite hilarious…but the second “logical” train is all over the internet (the “cascade of medical interventions that ends in an unnecesarean”) and espoused repeatedly by all kinds of people involved with pregnant women…midwives, childbirth educators, doulas…and in case you think I’m being discriminatory, let me just say that I’ve also run into several doctors and LDR nurses that believe this too.
The problem is that women with babies that are OP (sunny side up) or asynclitic (head tilted to the side) or otherwise not in the optimum presentation for labour and delivery tend to experience more pain with contractions…the infamous “back labour” in the case of OP presentation. These women are more likely to request epidural analgesia. During labour uterine contractions push the presenting part of the fetus against the cervix causing it to thin and dilate…if the fetal head is not well applied to the cervix that process is going to be slower or may stall. As the cervix gets stretched, it releases prostaglandins that have actions in intensifying labour (a positive feedback loop, this is also how stripping those membranes can help you go into labour sooner). If cervical dilation is slow or doesn’t occur, this positive feedback loop is interrupted. Pitocin/ oxytocin is then used to try to get things back on track but it’s not always successful and it’s easy to see, once you have a deeper understanding of physiology of the labour and delivery process, how there can be an association between epidurals, pitocin and C/S without any causation.
Observational trials (non-randomized) that have found an association between epidurals and prolonged labour and operative delivery, have also found that women who experience more pain in early labour are more likely to have prolonged labours, problems with the fetal heart rate and to require instrumental delivery (23). More pain will result in more requests for epidural analgesia. Lets not get confused here…it’s not the epidural per se that is resulting in longer labours, FHR problems and operative or instrumental delivery.
A meta-analysis of nine studies looking at the effect of epidurals on the length of the first stage of labour (dilating to 10 cm) found no difference (8). These studies included women having their first baby (primips) as well as those who were on baby number 2 or more (multips). The definitions used for the start and end of the first stage of labour differed across studies also. A single study from Parkland hospital on primips found that women randomly assigned to epidurals had a longer first stage – but only by an average of 30 minutes (20). There are two randomized studies that had the opposite result however, both Wong et al (22) and Ohel et al (18) found that the duration of the first stage was shorter in women who received an epidural before 4 cm dilation compared to women who didn’t. Hmm…is that not the opposite of what you hear on message boards all the time?…ie…”if you have to get an epidural, try to wait until after 4 cm or your labour will slow or possibly stop and you’ll end up with an unnecesarean.” More about that at the end of this post.
Some researchers have found that contractions decrease after an epidural is placed (21) but that most of the effect seems to be due to maternal malpositioning resulting in aortocaval compression by the uterus (ie inadequate left lateral tilt with a wedge under the hip). There is also an association with a fluid bolus and decreased contraction activity (2, 25). It used to be standard to give a fluid bolus when placing an epidural but there is no evidence that this practice is beneficial and it may be harmful. Anesthesiologists stopped doing this routinely and I was never taught to do it. In one neat little study (15) uterine activity was measured with intrauterine catheters before and after epidurals were placed in 11 primips…there was no change in activity.
An epidural may speed up uterine activity in women who have high levels of circulating adrenaline and noradrenaline due to pain and anxiety (11, 13). Epinephrine relaxes the uterus. Take it away and contractions can speed up – we half-jokingly refer to this as an epidural “induction”. In fact, if you take it away quickly enough, the uterus can become hypertonic and squeeze so hard that a transient fetal bradycardia may occur. That’s a known effect which is easily treated at the bedside and does not result in an emergency unnecesarean.
What about the second stage? It’s pretty intuitive to think that labour epidural analgesia, which can be accompanied by some muscular weakness, will result in less effective pushing as well as the loss of feedback during pushing (eg feeling the baby come down with good pushes and not feeling movement with ineffective pushes). Indeed, meta-analyses show that the second stage is prolonged in women with epidurals by an average of 15 minutes (8, 20). Some women fear that they are “on the clock” during the second stage…ie if they don’t manage to push the baby out within a certain time limit they will be subject to an unnecesarean or instrumental delivery. You should know that if the fetus is okay (electronic FHR monitoring does not show non-reassuring status) and progress is being made (even if slow), the American College of OB/Gyns (ACOG)’s position is that a prolonged second stage alone is not an indication for intervention. Note, this does not mean pushing for four hours at home with a CPM, a situation that is dicey due to lack of monitoring and access to timely intervention.
What about instrumental delivery? The odds ratio of assisted vaginal birth, from the Cochrane review, is 1.42 for women with an epidural. The anesthesiology community here thinks there is a dose-related effect. A denser epidural leads to more pelvic floor relaxation which in turn could interfere with fetal rotation during descent. We have lots of studies where instrumental delivery was increased by epidural use and some where it wasn’t. Many different epidural drug concentrations and combinations were used in these studies and there is some evidence that a dose-response effect does occur (7, 10, 14, 17). For example, the use of instrumental delivery was double in women getting 0.125% bupivacaine in their epidural compared to a saline placebo group(3) but there was no difference compared to placebo for women getting 0.0625% bupivacaine with fentanyl (4). Right now we’re really struggling with the best combination of epidural meds that will provide good analgesia without increasing the need for instrumental delivery and the solution for any individual woman is likely going to vary. Anesthesiologists really do care about this – we know from research done by our colleagues that instrumental delivery has risk for mom (more third and forth degree tears, more episiotomy, more risk of fistulae) and more risk for babies if mid-station forceps are required.
If avoiding an instrumented delivery is important to you but you want an epidural, mention this to your anesthesiologist to encourage them to use a lower concentration epidural solution. We’ll work with you to maximize your chances of achieving the outcome you want.
In terms of Cesarean delivery rates, in the two meta-analyses of randomized controlled trials mentioned earlier, women with epidurals have the same C/S rate as those without (8, 20). We also have good information from impact studies – before and after studies of C/S rates around the time of epidural introduction to hospitals. There is a great example for the Tripler Army Hospital in Hawaii. Before 1993 the epidural rate in this hospital was about 1%. After 1993, the hospital created a policy that mandated on-demand access to epidurals for women in labour. In one year, the epidural rate increased to 80%…but the Cesarean delivery rate for primips remained at 19% (24). Another similar study looked at the National Maternity Hospital in Dublin (9) from 1987 when the epidural rate was 10% compared to 1994 when the epidural rate was 57%. In both years, the Cesarean rate was 4%. A meta-analysis of these impact studies, involving over 37 000 women, showed no increase in C/S rates when epidurals were made available.
Retrospective observational studies suggested an increase in C/S rate when epidurals were used prior to 4 cm dilation (1). However, these studies suffered from selection bias – remember, women who experience more pain early in labour have a higher risk of prolonged labour, instrumental delivery and C/S regardless of whether or not they get an epidural. Randomized controlled trials to look at this issue have found no association between epidurals in early labour and an increased risk of C/S (5, 6, 12, 22, 18). This lead the ACOG to release the following statement (1):
“Neuraxial analgesia techniques [epidurals and combined-spinal epidurals] are the most effective and least depressant treatments for labour pain. The American College of Obstetricians and Gynecologists previously recommended that practitioners delay initiating epidural analgesia in nulliparous women until the cervical dilation reached 4-5 cm. However, more recent studies have shown that epidural analgesia does not increase the risks of cesarean delivery. The choice of analgesic technique, agent and dosage is based on many factors, including patient preference, medical status, and contraindications. The fear of unnecessary cesarean delivery should not influence the method of pain relief that women can choose during labour.”
Couldn’t have said it better myself! There is no evidence that you need to wait to achieve a certain level of cervical dilation before getting an epidural. Provided that you can comply with the need to be positioned for placement and to hold still, there is no cut-off for getting an epidural or combined spinal-epidural (CSE) either. No word of a lie, I’ve put a CSE in someone who was fully dilated at her request. Why deny someone pain relief when you know she might be pushing for an hour or two? Now this is within reason, of course. If the baby is coming fast (ie is pretty much crowning) that’s probably too late! If you get the run around because you are 9 cm but you can hold still and get into a curled forward position for placement, there is no reason that some crusty old-school anesthesiologist shouldn’t put in your epidural – you just (regrettably) might have to get a little obnoxious about it.
Personally, I don’t care if you get an epidural or not. Simply not liking the idea is a good enough reason to avoid one if you can…but it really gets my panties in a twist when women decide they don’t want an epidural based on these pervasive lies that they greatly prolong labour or lead to unnecesarians. We are failing women if they are making decisions based on old or inaccurate information. In fact, if your provider perpetuates these untruths, I would seriously question them on other aspects of their care. They are either ignorant (these studies have been available since 2000 or earlier – that’s 12 years ago!) or lying to you and I, for the life of me, can’t decide which of those two scenarios is worse.
- American College of Obstetricians and Gynecologists Committee on Obstetric Practice. Analgesia and cesarean delivery rates. ACOG Committee Opinion No 339. Washinton, DC, ACOG, June 2006. (Obstet Gynecol 2006; 107:1487)
- Cheek TG et al. Normal saline iv fluid load decreases uterine activity in active labour. Br J Anaesth 1996; 77:632-5
- Chestnut et al. The influence of continuous epidural bupivacaine analgesia on the second stage of labor and method of delivery in nulliparous women. Anesthesiology 1987; 66:774-80.
- Chestnut et al. Continuous epidural infusion of 0.0625% bupivacaine-0.0002% fentanyl during the second stage of labor. Anesthesiology 1990; 72:613-8
- Chestnut et al. Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are in spontaneous labour? Anesthesiology 1994; 80:1201-8
- Chestnut et al. Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are receiving intravenous oxytocin? Anesthesiology 1994; 90:1193-1200
- Comparative Obstetric Mobile Epidural Trial (COMET) Study Group UK. Effect of low-dose mobile versus traditional epidural techniques on mode of delivery: A randomised controlled trial. Lancet 2001; 358: 19-23
- Halpern et al. Epidural analgesia and the progress of labour. In Halpern SH, Douglas MJ, editors. Evidence-based Obstetric Anesthesia. Oxford, Blackwell, 2005:10-22.
- Impey et al. Epidural analgesia need not increase operative delivery rates. Am J Obstet Gynecol 2000; 182:358-63
- James et al. Comparison of epidural bolus administration 0f 0.25% bupivacaine and 0.1% bupivacaine with 0.0002% fentanyl for analgesia during labour. Br J Anaesth 1998; 81:501-10
- Lederman et al. The relationship of maternal anxiety, plasma catecholamines and plasma cortisol to progress in labor. Am J Obstet Gynecol 1978; 132: 495-500
- Luxman et al. The effect of early epidural block administration on the progression and outcome of labor. Int J Obstet Anesth 1998; 7:161-4
- Moir et al. Management of incoordinate uterine action under continuous epidural analgesia. Br Med J 1967; 3:396-400
- Nageotte et al. Epidural analgesia compared with combined spinal-epidural analgesia during labor in nulliparous women. N Engl J Med 1997; 337: 1715-9
- Nielsen et al. Effect of epidural analgesia on fundal dominance during spontaneous active-phase nulliparous labour. Anesthesiology 1996; 84:540-4
- Nobel et al. Continuous lumbar epidural analgesia using bupivacaine: A study of the fetus and newborn child. J Obstet Gynaecol Br Commonw 1971; 78:559-63
- Olofsson et al. Obstetric outcome following epidural analgesia with bupivacaine-adrenaline 0.25% or bupivacaine 0.125% with sufentanil – a prospective randomized controlled study in 1000 parturients. Acta Anaesthesiol Scan 1998; 42: 284-92
- Ohel et al. Early versus late initiation of epidural analgesia in labour: does it increase the risk of cesarean section? A randomized trial. Am J Obstet Gynecol 2006; 194:600-5.
- Seyb et al. Risk of cesarean delivery with elective induction of labor at term in nulliparous women. Obstet Gynecol 1999; 94:600-7
- Sharma et al. Labour analgesia and cesarean delivery: an individual patient meta-analysis of nulliparous women. Anesthesiology 2004; 100:142-8
- Schellenberg JC. Uterine activity during lumbar epidural analgesia with bupivaicaine. Am J Obstet Gynecol 1977; 127: 26-31
- Wong et al. The risk of cesarean delivery with neuraxial analgesia given early versus late in labor. N Engl J Med 2005; 352: 655-65
- Wuitchik M et al. The clinical significance of pain and cognitive activity in latent labour. Obstet Gynecol 1989; 73:35-42.
- Yancy et al. Observations on labor epidural analgesia and operative delivery rates. Am J Obstet Gynecol 1999; 180:353-9
- Zamora et al. Haemodynamic consequences and uterine contractions following 0.5 or 1.0 litre crystalloid infusion before obstetric epidural analgesia. Can J Anesth 1996; 43:347-52