These studies help show which babies may stay occiput posterior using modern university labor and delivery practices.
Finish researcher Gardberg has helped us understand the rates of occiput posterior and how often they rotate. We'll start with a 1998 Gardberg study here and I'll refer you over to the 2005 Lieberman study which finds similar rates, though reports it as new information. Both show that about 1/3 of babies that start OP stay OP. Again, we miss the rates of left occiput transverse (lateral) and right occiput transverse (lateral) and the route of rotation for these babies.
Obstet Gynecol. 1998 May;91(5 Pt 1):746-9.
This is the abstract altered to be more readable with Gail's comments in bold added.
OBJECTIVE: To use intrapartum sonography [ultrasound in labor] as a tool to investigate the development of the persistent occiput posterior position during labor, as well as to identify parameters correlating with the outcome of labor.
METHODS: A prospective study of 408 women in labor after 37 weeks' gestation with a singleton fetus in a vertex position using sonography at the onset of labor was performed. Fetal position, placental location, and maternal BMI (body mass index) were recorded. Outcome of labor was monitored for all relevant parameters.
RESULTS: Most (68%) of persistent occiput posterior positions develop through a malrotation during labor from an initially occipitoanterior position. Gail asks, Are we including ROT and LOT here?
Only 32% of persistent cases were occipitoposterior (dorsoposterior) at the onset of labor; operative interventions were required in 87.5% of these. One third of OP babies stay OP. [Emphasis mine.]
Of the 61 (15%) occipitoposterior positions at the onset of labor, 53 (87%) rotated into an occiput anterior position. Most OP babies rotate. [Emphasis mine.]
More of the babies who started labor in a posterior position ended in a posterior position. [Emphasis mine.] Persistent occiput posterior position was more common in the initially occipitoposterior group (P < 0.01, Fisher exact test), and posterior placental locations were fewer (z test, P = 0.05).
Also, operative deliveries were more common in the group remaining occipitoposterior throughout labor.
Larger women (higher maternal BMI) had larger babies, more operative deliveries, babies with lower Apgar scores at 1 minute, and more posterior placentas
CONCLUSION: In most cases, persistent occiput posterior position develops through a malrotation and only in a little more than one-third of cases through absence of rotation from an initially occipitoposterior position. Higher maternal BMI correlates with higher fetal weight, increased operative deliveries, lower Apgar scores at 1 minute, and posterior placental locations. Intrapartum sonography proved to be useful in investigating the development of the persistent occipitoposterior position.