Today we are joined by Dr. Santosh Pandipati and Dr. Sarena Hayer, who talk to us about climate change and how it can affect pregnant individuals and their fetuses.
Dr. Pandipati is a board certified maternal fetal medicine specialist.
Dr. Hayer is a third year Ob/Gyn resident at OHSU.
Previous podcasts:
Part 2 of Preventing the Primary Cesarean (old - for comparison)
Limiting Interventions in Labor and Birth (based on CO 766)
Also check out for reading for this podcast specifically:
- Committee Opinion 766 on Approaches to Limiting Intervention in Labor and Birth
Continuous labor support
Defined: continuous presence of support personnel or the continuous presence of a one-on-one person for support.
This support comes in many forms, including:
Emotional support
Information about labor progress
Advice about coping techniques
Providing/facilitating comfort measures
Speaking up on behalf of the pregnant individual, when needed
Noted in CPG8 as “one of the most effective tools to improve labor and delivery outcomes.”
Systematic review: pregnant women allocated to continuous support benefitted from:
More likely to have SVD (RR 1.08, 95% CI 1.04 - 1.12)
Less likely to have negative feelings of childbirth experience (RR 0.69, CI 0.59 - 0.79)
Less likely to use any intrapartum analgesia (RR 0.90, 95% CI 0.64 - 0.88).
Have shorter labors (-0.69 hrs; 95% CI -1.04 to -0.34)
Less likely to have cesarean birth (RR 0.75, CI 0.64 - 0.88)
Less likely to have operative vaginal delivery (RR 0.90, CI 0.85 - 0.96)
Less likely to have neonate with 5-min Apgar < 7 (0.62, CI 0.46 - 0.85)
CPG 8 notes that OB/Gyns and health care providers/organizations should strive to develop policies and programs to integrate trained support personnel into intrapartum care to provide one-to-one support for laboring persons.
The Peanut Ball
Elongated, peanut-shaped ball, typically placed between a patient’s legs during labor while the patient is side-lying in order to “open up the pelvis.”
In theory, this mimics upright positioning with the opening of the pelvis.
A systematic review of four randomized trials of 648 patients found no significant difference for time in labor or incidence of vaginal delivery/cesarean delivery with peanut ball use.
There were nonsignificant trends towards improving vaginal delivery rates and shortening first stage length
However, evidence is further limited as guidance for how to use, what size to use, how long to use, when to use…
How the peanut ball is implemented in labor courses is heterogenous and driven a lot by personal/nursing experience.
More studies are needed to understand when/if it might be efficacious in particular scenarios.
Position Change and Ambulation
Similarly to the peanut ball, there are many opinions on this!
Observational studies find that patients assume many different positions during labor when left to their own devices on what is comfortable.
A meta-analysis comparing upright positioning (sitting/standing/kneeling), ambulation, or both with recumbent, lateral, or supine positions during first stage of labor found that upright positions:
Reduced first stage length by approximately 1h 22 min (95% CI -2.22 to -0.51 hr)
Less likely to undergo cesarean (RR 0.71, 95% CI 0.54-0.94)
A separate review found no differences in these factors, but found reduced trauma to pelvic floor for those in kneeling position.
CPG 8 encourages position changes to enhance maternal comfort and promote optimal fetal positioning.
Hydration modalities
CPG 8 notes that IV hydration is safe, but limits freedom of movement and overall may not be necessary
Oral hydration can be encouraged to meet caloric and hydration needs.
They review a systematic review comparing 250cc/hr of IV fluid to 125cc/h in low risk patients in spontaneous labor at term, demonstrating a lower risk of cesrean for any indication in the 250cc/hr group (12.5% vs 18.1%, RR 0.70).
Higher fluid rates also shortened duration of labor by mean of about 1 hour, and second stage specifically by just under 3 mins.
Also did not observe increasing maternal or neonatal morbidities, including pulmonary edema.
Recommended increased hydration for nulliparous women when oral intake is restricted.
Further study is needed to compare when oral intake / oral hydration is not restricted; when patients are undergoing induction of labor; or if comorbidities exist.
Cervical examinations
Frequency of cervical examination is frequently cited as a concern for infection, and has to be balanced against understanding labor progress and preventing arrest/dystocia.
The CPG authors note a retrospective cohort study of 2400 patients over 4 years showing no significant association between number of cervical exams in labor and intrapartum fever.
The association was also not present when confined to exams after amniotomy.
Welcome back! Last time, we talked the new Clinical Practice Guideline #8 and the first stage of labor. While there were some new things, many of the recommendations were unchanged.
Today we’re going to talk second stage – time from complete dilation to fetal delivery. There are some big differences here versus the previous Obstetric Care Consensus, and we’ll try to point them out as we go!
What is a normal length of second stage?
ACOG defines a prolonged second stage as:
Three hours or more in nulliparas
Two hours or more in multiparas
Furthermore, they recommend an individualized approach to diagnose second stage arrest, “incorporating factors regarding progress, clinical factors that may affect the likelihood of vaginal delivery, discussion of risks and benefits of available interventions, and individual patient preference” if planning to extend beyond these parameters.
Additionally, ACOG states that “second stage arrest can be diagnosed earlier if there is lack of fetal rotation or descent despite adequate contractions, pushing efforts, and time.”
This is a more open, individualized, and less time-focused than the prior “4/3/3/2” recommendations in the Obstetric Care Consensus.
The OCC also stated that there was no maximum amount of time in the second stage identified.
The recommendation to consider diagnosis prior to reaching these time points is based on some concerns that developed in the literature that providers were failing to recognize issues in the second stage altogether by focusing on the “4/3/3/2” time, and that the “4/3/3/2” recommendations were not based in evidence supporting safety.
CPG 8 takes an attempt at establishing some evidence:
Observational study of over 53,000 laboring patients:
Probability of vaginal delivery decreased with prolonged pushing time, but:
At 4 hours, chance of vaginal delivery in nullipara remained 78%
At 2 hours, chance of vaginal delivery in multipara remained 81%
Longer pushing duration resulted in statistically significant rise in composite neonatal morbidity
However, the absolute risk difference was small – less than 1%.
Other studies have been mixed about neonatal outcomes with respect to prolonged second stage.
Longer pushing duration resulted in rise in maternal risk:
3rd/4th degree laceration
Operative vaginal delivery
Postpartum hemorrhage
Cesarean delivery
If you remember the Obstetric Care Consensus, you might remember that the “additional hour of pushing time” was allotted for patients who had epidurals. Is that the same?
They do note in the text that, based on Consortium for Safe Labor data, second stage was prolonged by about one additional hour in patients with an epidural.
The additional clinical factors to consider include things like position (i.e., OP), maternal BMI, fetal weight, and the fetal station at time of complete dilation.
However, studies performed since then demonstrated that, while prolonging the second stage by an additional hour resulted in more vaginal deliveries, it also increased risk of neonatal acidemia, NICU admission, and 3rd/4th degree lacerations.
Thus, individualized discussions and management are highly encouraged. Keep the following in mind:
Ongoing management of the second stage presumes continued demonstration of fetal descent. The limits written are total expected times for second stage – so if you’re not seeing anything, that’s cause for concern.
95% of patients are at 0 station or lower (on -5 to +5 scale) at complete dilation – so if patients are higher than this, that is also concerning.
How do I manage a prolonged second stage?
Pushing timing
ACOG recommends commencing pushing when complete cervical dilation is achieved.
ACOG discusses the controversy surrounding “delayed pushing” or “passive descent” in this document, raising the findings of a recent high-profile RCT as well as a meta-analysis of 12 trials on the subject.
The arguments go that delayed pushing minimizes patient exertion with pushing efforts, while immediate pushing more closely mimics the physiology of unanesthetized patients, whose pain makes them push earlier.
Among high-quality studies, delayed pushing does not improve vaginal delivery rates.
Additionally, delayed pushing prolongs time in labor; and in the high-profile RCT, the study was stopped early because of increased rates of chorioamnionitis, postpartum hemorrhage, and neonatal acidemia in the delayed pushing arm.
So get to pushing!
Manual rotation
Positions such as OT or OP can be difficult to achieve vaginal delivery due to the mechanics of the fetal head within the pelvis.
Using a hand to rotate the head into an OA position has been demonstrated in observational studies to be successful about 70% of the time, while reducing cesarean and operative delivery rates, and not causing infant harm.
However, an RCT comparing a sham rotation to true rotation did not demonstrate any benefit, but was not powered to determine any risk of harm.
Knowing position of the fetal spine may help influence success, as has been demonstrated in one RCT – so don’t be afraid to have an ultrasound to 1) confirm position before rotation, and 2) help know which way to rotate!
Timing of manual rotation has not been adequately studied, so it can be performed at any point in the second stage.
Operative delivery
ACOG suggests an assessment for operative vaginal delivery before performing cesarean for second stage arrest.
Outcome comparisons of operative vaginal delivery and unplanned cesarean delivery demonstrate reduced maternal morbidity after successful operative delivery, with similar rates of serious neonatal morbidity.
This is no surprise to our listeners who have tuned in to our operative vaginal delivery podcast!
Check out that podcast for more details – but the rates of intracranial hemorrhage are similar for second stage cesarean and vacuum delivery, and failure rates are low – under 3% for low or outlet procedures.
That said, operative delivery requires special skill and training, which is becoming less frequent. Cesarean is still the “safety backstop” when these cannot be performed or if a patient declines operative delivery.
Be prepared for higher rates of endometritis and for more significant bleeding and hysterotomy extensions.
Listen to our recent podcast on difficult fetal extractions, too, as you’ll encounter this more frequently with second stage cesarean.
Back in 2019 we did a two-part series on preventing the primary cesarean (part 1, part 2). That series was based on the joint ACOG/SMFM Obstetric Care Consensus #1. As of the January edition of the Green Journal, ACOG & SMFM have now issued revised guidance in Clinical Practice Guideline #8 that retires the old document and shakes some things up a bit!
In that spirit, we’ll review some definitions following CPG 8 and remark on some of the new changes as we go along.
Part two of CPG 8 also reviews evidence behind some ways to limit intervention in labor and delivery – we’ve podcasted on that before, too – but we’ll save that for a future episode.
Some definitions to get started:
Labor: onset of regular, painful uterine contractions resulting in cervical dilation, effacement, or both.
First stage: the time period from labor onset until full dilation (10 cm) is achieved. This is broken down into:
Latent phase: gradual, slow, early cervical change.
Active phase: time period of more rapid, predictable cervical change.
Second stage: the time period from complete dilation until delivery of the fetus, characterized by maternal pushing efforts.
Third stage: the time period from delivery of the fetus until delivery of the placenta.
How did we come up with these stages?
1950s: Emanuel Friedman publishes graphs of cervical dilation of 1,000 term patients admitted to the hospital in spontaneous labor, and describe the period of rapid cervical change that characterizes “latent” from “active” first stage, in addition to a “deceleration” phase near the end of first stage.
This transition from latent to active in his data was thought to occur at around 4cm cervical dilation.
The 95%ile for active phase dilation was 1.2 cm/h in nulliparas, and 1.5cm/h in multiparas.
2010: Zhang et al publish updated data using the Consortium for Safe Labor
Almost 63,000 term patients at 19 US hospitals with normal perinatal outcomes. Key takeaways:
The transition point from latent to active seemed to occur at around 6cm in both nulliparas and multparas, later than Friedman observed.
The rate of active phase cervical dilation was also slower than Friedman’s observations:
Nulliparas: 0.5 - 0.7 cm/h
Multiparas: 0.5 - 1.3 cm/h
Since 2010, multiple other studies using large data sets have been published – they’re too numerous to review, but in short, there seem to be several clinical factors that might affect labor progress.
Obesity
Hypertension
Gestational age
Multiple gestations
Presence of fetal anomalies
Fetal size
Fetal sex
Latent Phase of First Stage
In the Friedman curve, they demonstrated a 95%ile of latent phase length ranging from 14h in multiparas to 20h in nulliparas.
Subsequently, in the Zhang and other curves, the data was all over the place. A conservative 95th percentile, per ACOG, seems to be around 16 hours.
Likely, this has something to do more with when someone is admitted to the hospital, and characterizing the length of latent phase is difficult to do.
Prolonged latent phase is somewhat associated with adverse obstetrical outcomes, but
The vast majority of people who have prolonged latent phase will either:
1) stop contracting, or
2) achieve active phase, particularly with amniotomy or oxytocin augmentation.
Therefore, there is no recommendation for defining “arrest of latent phase” or “failed latent phase.”
As long as maternal and fetal status are appropriate, latent phase may continue.
Not changed from prior guidance.
What about induced labor and latent phase?
Induced labor is different - there is a definition of “failed induction of labor.”
Induced labor has a much longer potential latent phase, so the guidance is very conservative in order to maximize opportunities to get the patient into the active phase.
Recommendation: Oxytocin should be administered for a minimum of 12-18 hours after membrane rupture before deeming induction unsuccessful.
This recommendation is provided otherwise reassuring maternal/fetal status.
Going beyond 18 hours can be discussed with patients on an individual basis.
This recommendation is based on studies demonstrating only about 5% of patients remain in latent phase after amniotomy with oxytocin administration after 18h.
This is largely an unchanged recommendation, but the previous Obstetric Care Consensus mentioned waiting until 24 hours.
Acknowledged this was based on expert opinion.
So in the context of the CPG, shared-decision making is recommended rather than overtly recommending a 24 hour period after amniotomy to diagnose failed induction.
Active Phase of First Stage
ACOG definitively puts forth a recommendation: the active phase of labor is denoted at 6cm dilation.
This is based on the more conservative Zhang data
They acknowledge there may be a range of individualized starting points between 4-6cm based on individual patients.
The 6cm standard for active phase management allows as many as possible to be ruled in for active phase before the more stringent arrest definitions are applied.
Not changed from prior guidance (Obstetric Care Consensus).
ACOG defines active phase arrest in one of two ways:
No progression in cervical dilation after 6cm with rupture of membranes despite adequate contractions for 4 hours, or
No progression in cervical dilation after 6cm with rupture of membranes despite inadequate contractions and oxytocin augmentation for 6 hours.
Versus the old document, this is largely unchanged.
A protracted active phase can be conservatively defined as less than 1cm of cervical change in 2 hours.
They note slow, but progressive, labor in the first stage should not be an indication for cesarean:
A prospective study of over 300 patients with dysfunctional labor, when provided 4 additional hours of oxytocin, 50.7% of nulliparas and 41.7% of multiparas ultimately delivered vaginally.
This would have equated to a cesarean rate of over 35% without the additional time, versus just 18% with the additional time.
Since providing these recommendations in 2014 with the original Obstetric Care Consensus, real-life benefit to cesarean rates have been mixed / modest at best.
There is not much data at all regarding maternal/neonatal morbidity.
However, the CPG authors describe that this approach likely balances risks of prolonged labor with benefits of avoiding cesarean in a safe way, based on the best data available.
Managing an Abnormal First Stage of Labor
New to this document is an endorsement of an active management approach to the first stage of labor, which includes:
Standard criteria for diagnosis of arrest of labor
Early amniotomy
Administration of oxytocin for protracted labor
One-to-one nursing care
Studies of active management have not shown reduction in cesarean rates, but do point towards lower rates of maternal fever and shorter duration of labor.
Thus, knowing risks of protracted labor, ACOG endorses active management - new to this CPG and stands out as an addition versus the prior Obstetric Care Consensus.
Let’s review the components - we just talked about arrest definitions, so next we’ll talk:
Amniotomy
ACOG recommends amniotomy for patients undergoing augmentation or induction of labor to reduce the duration of labor.
An AHRQ-based systematic review of amniotomy in spontaneous labor determined that it helped reduce length of labor in nullliparas, without increasing risk for cesarean delivery, maternal infection, trauma to the pelvic floor, or postpartum hemorrhage.
There was no difference in rate of cord prolapse, either, in any of the randomized trials analyzed.
When should I perform amniotomy?
This in the literature is broken down into early vs late, where “early” is often defined as amniotomy as soon as feasible.
In one RCT, this was within 1 hour of Foley removal when used for cervical ripening, versus late being beyond 1 hour - higher rates of vaginal delivery within 24h and shorter labor duration in early group.
Another RCT - amniotomy concurrent with oxytocin starting, vs 4 hours after starting oxytocin – demonstrated shorter labor length in nulliparas and no effect on cesarean delivery rates.
Systematic review of four other RCTs of induced labor - average labor reduction of 5 hours, with similar rates of cesarean and no increasing risks of complications.
ACOG concludes that “there is high-quality evidence to recommend early amniotomy as adjunctive to the labor process” – a really significant new recommendation!
Oxytocin use
ACOG recommends either high-dose or low-dose oxytocin regimens as reasonable to use with active labor management to reduce operative deliveries.
Similar to amniotomy, ACOG first discusses early vs late oxytocin augmentation, where early is defined as starting oxytocin once prolonged active phase is identified:
A few meta-analyses demonstrate modest increases in likelihood of vaginal delivery and modest reduction in cesarean birth.
Probably of more controversy is the use of high-dose vs low-dose protocols.
Low dose protocols generally use a starting dose of 0.5 - 2.0 mU/min, and increase by 1-2 mU/min every 15-40 minutes.
High dose protocols use a starting dose of 4 mU/min or higher, and increase by 3-6 mU/min every 15-40 minutes.
The data does not demonstrate any improved or worsened outcomes with one approach versus another, so ACOG states either approach is reasonable.
The previously-mentioned AHRQ systematic review did demonstrate lower cesarean rates and no difference in hemorrhage for nulliparous patients undergoing high-dose protocols – worth a consideration.
ACOG also notes a maximum dose of oxytocin has not been established – that was news to me!
ACOG does add a recommendation to use IUPCs in patients with protracted active labor, or in those whose contractions cannot be monitored externally.
They note IUPCs are a useful tool to help titrate oxytocin while also not causing or increasing adverse events.
Recall, 200 Montevideo units (MVUs) define adequacy, when looking at contraction strength in a ten-minute period.
There is some limited evidence that cesarean delivery is more likely with lower MVUs; but these cut offs, patterns of contractions, and definition of adequacy all need more study!
What is “post-term”?
Recall the ACOG language surrounding pregnancy term status:
24-27’6 weeks: extremely preterm
28-33’6 weeks: preterm
34-36’6 weeks: late preterm
37-38’6 weeks: early term
39-40’6 weeks: term
41-41’6 weeks: late-term
42’0 and beyond: post-term
Birth certificate data in the US indicate:
About 5% of births happen at 41 weeks and beyond
About 0.25% of births happen at 42 weeks and beyond
Largely a consequence of how we manage that today - since we tend to induce folks before they get there in many systems.
Risk factors for a patient being post-term include:
Nulliparous
Obesity
AMA
Personal history of post-term births in prior pregnancies
Male fetus (interesting)
Certain fetal conditions that likely interrupt signaling for parturition – i.e., anencephaly, placental sulfatase deficiency/X-linked ichthyosis
What’s the problem with post-term pregnancies?
Think of the fetus “overstaying its welcome.” There are multiple consequences:
Macrosomia
2.5-10% of post-term pregnancies have weights >4500g (vs only 1% at term)
“Dysmaturity”
Sign of chronic intrauterine malnutrition likely resulting from relative oligohydramnios, cord compression, meconium passage
Physical signs are what we think of for post-term pregnancies:
“Parchment-like” skin – less vernix, skin peeling, feels thin
Meconium staining of amniotic fluid and skin; increased risk of meconium aspiration
Long, thin bodies and long fingernails
Hypoglycemia
Polycythemia
Increased risk of perinatal morbidity/mortality
Fetuses born after 42 weeks have higher rates of NICU admission, seizures, meconium aspiration, and 5-minute Apgars under 4.
Oligohydramnios rates go up the longer pregnancy goes, predisposing to risks associated with oligohydramnios.
Remember, because of stillbirth risk, in isolation delivery for oligo is recommended anytime after 36 weeks!
Infants born at 41 weeks or greater also have about a one-third higher risk of perinatal death versus those born at term gestation.
This risk increases to:
2x greater risk at 42 weeks;
4x greater risk at 43 weeks; and
5-7x at 44+ weeks.
Importantly, while these relative risks are quite high, it should also be stated the absolute risk is low:
The stillbirth risk at 40 weeks is less than 1 per 1,000 ongoing pregnancies.
At 41-42 weeks, this increases to 1.2 - 1.3 / 1000.
At 42-43 weeks, 1.3 - 1.9 / 1000.
At 43-44 weeks, 1.5 - 6 / 1000.
There are also maternal risks to ongoing pregnancy:
A large observational study has suggested increased rates of many major OB morbidities, including:
Higher order laceration
Postpartum hemorrhage
Infection
Cesarean delivery
How do I manage a post-term pregnancy?
One really important thing to always confirm (and a limitation to some of the data we’ve described) is accurate pregnancy dating.
Check out our previous episode!
Some studies have shown that the incidence of post-term pregnancy was reduced from 9.5% to 1.5% when switching from LMP to ultrasound-based dating – underscoring the importance of early ultrasound!
This may ultimately help to decrease unnecessary intervention, whether that be for post-dates, incorrectly calling a fetus FGR, or delivering out of concern for macrosomia, amongst other issues.
Membrane sweeping gets mention in this practice bulletin!
Using a finger to “stir up” around the membranes at the internal os, releasing endogenous prostaglandins.
Cochrane review demonstrates it reduces incidence of pregnancies progressing past 41 weeks.
Use after a shared decision-making process with your patient.
Can be uncomfortable and cause some bleeding.
Fetal surveillance
ACOG recommends doing something for pregnancies progressing past 41 weeks, but stops short of making an outright specific recommendation.
This is because there are insufficient data comparing approaches for antenatal testing, and whether one reduces stillbirth risk better than another.
While ACOG does recommend antenatal testing, they also admit there are no RCTs demonstrating that fetal surveillance decreases perinatal morbidity or mortality.
The benefit is presumed in capturing and reducing risk where we can (i.e., finding oligohydramnios).
Some options (might bring you back a bit to our antepartum testing episode — or use that as a refresher!).:
Biophysical profile (BPP) or modified BPP
A small RCT has not demonstrated any difference between the two in neonatal outcomes when used in pregnancies beyond 42 weeks.
Advantageous in that you are getting NST as well as a fluid assessment to check for oligo.
One of the better, less invasive tests for negative predictive value of stillbirth.
For fluid assessment, deepest vertical pocket has been demonstrated to reduce unnecessary intervention without increasing adverse outcomes for fetuses.
NST alone
More convenient to do and does not require ultrasound.
Weekly or twice-weekly acceptable
Twice-weekly may be better based on some small studies, but data are insufficient – again, given the overall rare absolute outcomes of stillbirth or neonatal morbidity, these studies are difficult to adequately power.
Labor considerations
ACOG doesn’t provide any specific recommendations regarding labor management in this population, aside from one group: TOLAC.
There does not appear to be increased uterine rupture rates when advancing beyond 41 weeks, but
Failure of TOLAC risk increases – from 22.2% before 40 weeks, to 35.4% after 41 weeks.
This can be a conundrum – especially because of data suggesting increased success with spontaneous labor (which isn’t guaranteed!) versus a slightly increased risk of rupture with induction (remember that episode on TOLAC?).
Working through a shared decision making process and being aware of all of the risks can help your patients make the right decision for them.
How long can I let it go?
ACOG says that induction at 41’0 “can be considered” based on the limited evidence of increasing risk at/beyond this gestational age.
If advancing beyond 41’0, some sort of antenatal testing should be performed.
ACOG definitively recommends delivery at 42’0 and beyond, definitely by 42’6, due to the risks of morbidity/mortality.
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