Perinatal outcome of vaginal delivery with epidural analgesia initiated at the early or late phase of labor period: A retrospective cohort study in the Japanese population

Effect of epidural analgesia on cervical ripening using dinoprostone vaginal inserts

OBJECTIVE

To clarify whether the duration from cervical ripening induction to labor onset is prolonged when epidural analgesia is administered following application of dinoprostone vaginal inserts vs. cervical ripening balloon.

METHODS

This retrospective study included mothers with singleton deliveries at a single center between 2020-2021. Nulliparous women who underwent labor induction and requested epidural analgesia during labor after 37 weeks of gestation were included. The duration from cervical ripening induction to labor onset was compared between women using a dinoprostone vaginal insert and those using a cervical ripening balloon and between women who received epidural analgesia before and after labor onset.

RESULTS

In the dinoprostone vaginal insert group, the duration was significantly shorter in the subgroup that received epidural analgesia after labor onset (estimated median, 545 [95% confidence interval: 229-861 min]) than the subgroup that received it before labor onset (estimated median, 1,570 [95% confidence interval: 1,226-1,914] min, p = 0.004). However, in the cervical ripening balloon group, the difference between subgroups was not significant. The length of labor among the groups was also not significantly different.

CONCLUSION

Epidural analgesia as labor relaxant adversely affected the progression of uterine cervical ripening when dinoprostone vaginal inserts were used, whereas it did not affect cervical ripening when a mechanical cervical dilatation balloon was used. The present results are significant for choosing the appropriate ripening method.

Does the timing of neuraxial analgesia initiation in elective induction of multiparous women prolong the duration of delivery?

AIM

To investigate whether the early initiation of neuraxial analgesia prolongs the duration of electively induced labor in Japanese multiparous women.

METHODS

This retrospective study included multiparous term women who underwent elective induction of labor using combined spinal-epidural analgesia at the Showa University Hospital between October 2018 and March 2021. The participants were divided into two groups: early and late. If neuraxial analgesia was initiated when the cervical dilation was ≤3 cm, the patient was included in the early group. The remaining patients were included in the late group. The obstetric and neonatal outcomes were compared between the two groups. The primary outcome was the duration of delivery. The secondary outcomes were the rates of instrumental and cesarean deliveries.

RESULTS

Two hundred and ninety-seven women (early group = 139, late group = 158) were included in the analysis. The duration of the first stage of labor did not differ significantly between the early and late groups (median: 232 vs. 260 min, p = 0.35). Similarly, there was no significant difference in the duration of the second stage (37 vs. 40 min, p = 0.20). Moreover, the rates of instrumental and cesarean deliveries did not differ significantly between the groups, and the neonatal outcomes were comparable.

CONCLUSION

Early initiation of neuraxial analgesia in the elective induction of parous Japanese women did not prolong the duration of delivery. Our results suggest that neuraxial analgesia may be initiated whenever a parturient desires it.

Labor analgesia and its impact on the maternal and perinatal outcomes

OBJECTIVE

This study aimed to assess adverse maternal and perinatal outcomes in parturients undergoing labor analgesia.

METHODS

This was a retrospective cohort study in parturients who underwent labor analgesia. Parturients were categorized into three groups: Group 1 (n=83)-analgesia performed with cervical dilatation ≤4.0 cm; Group 2 (n=82)-analgesia performed with cervical dilatation between 5.0 and 8.0 cm; and Group 3 (n=83)-analgesia performed with cervical dilatation ≥9.0 cm.

RESULTS

Analgesia in parturients with cervical dilatation ≥9.0 cm showed a higher prevalence and a 3.86-fold increase (OR 3.86; 95%CI 1.50-9.87; p=0.009) in the risk of forceps delivery. Analgesia in parturients with cervical dilatation ≤4.0 cm showed a higher prevalence and a 3.31-fold increase (OR 3.31; 95%CI 1.62-6.77; p=0.0016) in the risk of cesarean section. Analgesia in parturients with cervical dilatation ≥9.0 cm was associated with a higher prevalence of fetal bradycardia (20.7%), a need for neonatal oxygen therapy (6.1%), and a need for admission to a neonatal intensive care unit (4.9%). Analgesia in parturients with cervical dilatation ≤4 cm was associated with a higher prevalence of Apgar score <7 at 1st minute (44.6%).

CONCLUSION

Performing labor analgesia in parturients with cervical dilatation ≤4.0 or ≥9.0 cm was associated with a higher prevalence of adverse maternal and perinatal outcomes.

The latent phase of labor

The latent phase of labor extends from the initiation of labor to the onset of the active phase. Because neither margin is always precisely identifiable, the duration of the latent phase often can only be estimated. During this phase, the cervix undergoes a process of rapid remodeling, which may have begun gradually weeks before. As a consequence of extensive changes in its collagen and ground substance, the cervix softens, becomes thinner and dramatically more compliant, and may dilate modestly. All of these changes prepare the cervix for the more rapid dilatation that will occur during the active phase to follow. For the clinician, it is important to recognize that the latent phase may normally extend for many hours. The normal limit for the duration of the latent phase should be considered to be approximately 20 hours in a nullipara and 14 hours in a multipara. Factors that have been associated with a prolonged latent phase include deficient prelabor or intrapartum cervical remodeling, excessive maternal analgesia or anesthesia, maternal obesity, and chorioamnionitis. Approximately 10% of women with a prolonged latent phase are actually in false labor, and their contractions eventually abate spontaneously. The management of a prolonged latent phase involves either augmenting uterine activity with oxytocin or providing a sedative-induced period of maternal rest. Both are equally effective in advancing the labor to active phase dilatation. A very long latent phase may be a harbinger of other labor dysfunctions.