How is labor affected when the fetus is in an occiput posterior op position?

The direct OP is the classic posterior position with the baby facing straight forward. Right Occiput Transverse [ROT] is a common starting position in which the baby has a bit more likelihood of rotating to the posterior during labor than to the anterior. Right Occiput Posterior usually involves a straight back with a lifted chin [in the first-time mother]. Left Occiput Posterior places the baby’s back opposite the maternal liver and may let the baby flex [curl] his or her back and therefore tuck the chin for a better birth. These are generalities, of course. See a bit more about posterior positions in Belly Mapping® on this website. Want to map your baby’s position? Learn how with the Belly Mapping® Workbook.

Pregnancy may or may not show symptoms. Just because a woman’s back doesn’t hurt in pregnancy doesn’t mean the baby is not posterior. Just because a woman is quite comfortable in pregnancy doesn’t mean the baby is not posterior. A woman can’t always feel the baby’s limbs moving in front to tell if the baby is facing the front.

The four posterior fetal positions

Four starting positions often lead to [or remain as] direct OP in active labor. Right Occiput Transverse [ROT], Right Occiput Posterior [ROP], and Left Occiput Posterior [LOP] join direct OP in adding labor time. The LOP baby has less distance to travel to get into an LOT position.

As labor begins, the high-riding, unengaged Right Occiput Transverse baby slowly rotates to ROA, working past the sacral promontory at the base of the spine before swinging around to LOT to engage in the pelvis. Most babies go on to OA at the pelvic floor or further down on the perineal floor.

If a baby engages as a ROT, they may go to OP or ROA by the time they descend to the midpelvis. The OP baby may stay OP. For some, once the head is lower than the bones and the head is visible at the perineum, the baby rotates and helpers may see the baby’s head turn then! These babies finish in the ROA or OA positions.

Feeling both hands in front, in two separate but low places on the abdomen, indicates a posterior fetal position. This baby is Left Occiput Posterior.

Studies estimate 15-30% of babies are OP in labor. Jean Sutton in Optimal Fetal Positioning states that 50% of babies trend toward posterior in early labor upon admission to the hospital. Strong latent labor swings about a third of these to LOT before dilation begins [in “pre-labor” or “false labor”].

Recent research shows about 50% of babies are in a posterior position when active labor begins, but of these, 3/4 of them rotate to anterior [or facing a hip in an occiput transverse, head down position.

Jean Sutton’s observations, reported in her 1996 book, indicates that some babies starting in a posterior position will rotate before arriving to the hospital. Ellice Lieberman observed most posteriors will rotate out of posterior into either anterior or to facing a hip throughout labor. Only 5-8% of all babies emerge directly OP [13% with an epidural in Lieberman’s study]. At least 12% of all cesareans are for OP babies that are stuck due to the larger diameter of the OP head in comparison to the OA head. It’s more common for ROT, ROP, and OP babies to rotate during labor and to emerge facing back [OA]. Some babies become stuck halfway through a long-arc rotation and some will need a cesarean anyway.

The three anterior starting positions for labor

The three anteriors — LOT, LOA, and OA — are all ideal fetal positions for the start of labor. Both LOA and OA require less rotation than LOT and may lead to a faster labor, but they may also be less common. Generally, very few midwives or doctors will pay strict attention to the actual head position, leading to the LOT baby often being referred to as LOA or just OA.

Why not ROA? ROA babies may have their chins up and this deflexed position may lengthen the course of labor. Less than 4% of starting positions are ROA, according to a Birmingham study. This might not be ideal for first babies, but is not a posterior position either. 

posterior [OP] positions account for 15 to 20% of cephalic presentations and are associated with poorer maternal and neonatal outcomes than occiput anterior [OA] positions. The aim of this study was to identify maternal, neonatal and obstetric factors associated with rotation from OP to OA position during the first stage of labor.

Material and methods

This secondary analysis of a multicenter randomized controlled trial [EVADELA] included 285 laboring women with ruptured membranes and a term fetus in OP position. After excluding women with cesarean deliveries before full dilatation, we compared two groups according to fetal head position at the end of the first stage of labor: those with and without rotation from OP to OA position. Factors associated with rotation were assessed with univariate and multivariate analyses using multilevel logistic regression models.

Results

The rate of anterior rotation during the first stage was 49.1%. Rotation of the fetal head was negatively associated with excessive gestational weight gain [adjusted odds ratio [aOR]: 0.37, 95% confidence interval [CI]: 0.17–0.80], macrosomia [aOR: 0.35, 95% CI: 0.14–0.90], direct OP position [aOR: 0.24, 95% CI: 0.09–0.65], and prelabor rupture of membranes [aOR: 0.40, 95% CI: 0.19–0.86]. Oxytocin administration was the only factor positively associated with fetal head rotation [aOR: 2.17, 95% CI: 1.20–3.91].

Discussion

Oxytocin administration may affect rotation of OP positions during the first stage of labor. Further studies should be performed to assess the risks and benefits of its utilization for managing labor with a fetus in OP position.

Introduction

Occiput posterior [OP] positions account for 15 to 20% of cephalic presentations at the onset of labor [1], [2], [3], [4]. Although spontaneous rotation in occiput anterior [OA] position occurs in most cases, the OP position persists at delivery in nearly 10% and is associated with obstetric complications, including prolonged labor, cesarean delivery, operative vaginal delivery, third- and fourth-degree perineal tears or lacerations, postpartum hemorrhage [PPH] and chorioamnionitis [5], [6], [7], [8], [9], [10], [11], [12]. The causation of posterior positions is multifactorial and observational studies report the following risk factors for their persistence at delivery: nulliparity, obesity, high maternal age, maternal sub-Saharan African origin, prolonged pregnancy, macrosomia, anterior placenta and epidural analgesia [1], [5], [13], [14], [15].

Nonetheless, the effectiveness of obstetric management strategies promoting the rotation of posterior positions, especially during the first stage of labor, remains to be demonstrated. Manual rotation is an effective method for turning the fetal head [16], but it is successful more often during the second stage of labor [17] and can sometimes cause fetal heart rate abnormalities, cervicovaginal injuries and in rare cases cord prolapse [18]. Another strategy uses maternal postures, such as hands-and-knees, lateral decubitus adapted to fetal station or lateral asymmetric decubitus. These are less iatrogenic and may promote earlier rotation, but randomized trials have not provided evidence of their effectiveness in promoting rotation of OP positions [19], [20], [21], [22]. Finally, other medical practices, such as analgesia, artificial rupture of membranes, or oxytocin infusion, are common during the first stage of labor, but studies that assess their effects on OP positions are lacking.

A better understanding of the factors affecting rotation of OP positions during the first stage of labor may help to promote earlier rotation and reduce obstetric complications associated with persistent OP positions. Accordingly, our principal objective was to identify maternal, neonatal and obstetric factors associated with rotation from OP to OA position during the first stage of labor. The secondary objective was to compare obstetric and neonatal outcomes associated with anterior rotation during this stage.

Section snippets

Material and methods

Our study presents a secondary analysis of data from the EVADELA multicenter randomized controlled trial [22]. This trial found no difference between lateral asymmetric decubitus posture [woman in a pronounced lateral recumbent position, lying on the side opposite that of the fetal spine, with her inferior leg positioned in the axis of the body and the upper leg hyperflexed] and a dorsal decubitus posture, for promoting the rotation of posterior positions.

The EVADELA trial recruited 322 women

Results

The fetal head rotated from an OP to an OA position during the first stage of labor for 140 [49.1%] of 285 women with a fetus in an OP position [Fig. 1]. Among women with an OP to OA rotation during the first stage, most of rotation [80.7%] occurred during the active phase of the first stage [i.e. cervical dilatation over 6 cm].

In the univariate analysis, the OP to OA rotation during the first stage was significantly more frequent for women with a gestational weight gain consistent with

Discussion

In our study, oxytocin administration during the first stage of labor was the only modifiable obstetric practice associated with OP to OA rotation. Individual factors negatively associated with rotation from OP to OA during the first stage of labor were also identified, including excessive gestational weight gain, macrosomia, direct OP position and prelabor rupture of membranes. As expected, obstetric outcomes were also better when fetus rotated from OP to OA during the first stage.

The

Ethical approval

The EVADELA trial protocol was registered in the US NIH Clinical trials database [no°NCT01854450] and approved by the Île de France XI Patient Protection Committee in February 2013 [no°13011]. Written consent of all participants was sought after antenatal and per partum information about the trial.

Contribution to authorship

All authors have made substantial contributions to: the conception and design of the study, or acquisition of data, or analysis and interpretation of data; drafting the article or revising it critically for important intellectual content; final approval of the version to be submitted.

Funding

Data comes from the EVADELA trial, funded by a research grant from the French Ministry of Health [CRC12002] and sponsored by the département de la recherche clinique et du développement de l’Assistance Publique–Hôpitaux de Paris.

Disclosure of interest

The authors declare that they have no competing interest.

Acknowledgments

We thank Nathalie Sellam [Pierre Rouquès–Les Bluets maternity hospital, Paris, France] and Jessy Guerin [Avranches-Granville maternity hospital, Granville, France] for their active participation in the EVADELA trial.

We thank all the women who agreed to participate in the trial and the midwives who recruited and included them. The sponsor was Assistance Publique–Hôpitaux de Paris [AP–HP, département de la recherche clinique et du développement]. The authors thank URC-CIC Paris-Descartes

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• Fetal malposition in labour and health outcomes for women and their newborn infants: A retrospective cohort study

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• Management of persistent occiput posterior position: The added value of manual rotation

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• Simple Models to Predict Vaginal Delivery and Spontaneous Fetal Occiput Rotation Based on Intrapartum Ultrasound and Maternal Characteristics

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• The Pathophysiology of Labor Dystocia: Theme with Variations

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