Hiya, have found this for you, don't know how common it is in my unit, but we do seem to see quite a lot. I believe that a sedentary lifestyle is thought to be to blame:
http://ancientpathsmidwifery.spaces....D099!453.entry Posterior baby study
Birth
Volume 33 Issue 2 Page 169 - June 2006
doi:10.1111/j.0730-7659.2006.0098c.x
Volume 33 Issue 2
Occipitoposterior Position in Labor
Elizabeth Shearer, MEd, MPH1
To the Editor,
I read the paper by Stremler et al (1), in the December 2005 issue of Birth
with interest, because a few years ago I served as coordinator for a study
on the association of changes in fetal position during labor and epidural
analgesia (2). The results of our study may shed some light on why Stremler
et al were unable to find a significant effect of position changes on the
incidence of occipitoposterior position, and also on why back pain in labor
is an imprecise indicator of occipitoposterior position.
In our study, lowrisk women were enrolled in early or earlyactive labor, and
given a series of bedside ultrasound examinations to determine fetal
position. We also asked women at enrolment to identify where they were
feeling the most pain (abdomen, back, etc.) and to mark on a visual analog
scale their current level of pain (0–10). We also determined the fetal
position at delivery (before any manual or instrumental rotation attempts).
We found that fetal position changes were common throughout labor, and the
final delivery position was not determined until very late in labor,
apparently in second stage. Overall, 36 percent of fetuses were
occipitoposterior at some point during labor. However, of fetuses who were
occipitoposterior late in first stage labor, only 21 percent were in that
position at delivery. Only 31 percent of those who were occipitoposterior at
delivery had been in that position at enrolment. In fact, 52 percent were
never occipitoposterior on any intrapartum ultrasound examination.
Furthermore, there was no association of back pain reported in early labor
and occipitoposterior position either at enrolment or at delivery. Given the
fluid nature of fetal position, this finding made perfect sense, even though
for many years as a childbirth educator, I firmly believed that back pain in
labor indicated occipitoposterior position.
Women who received epidural analgesia during labor were not more likely than
those who did not receive an epidural to have an occipitoposterior fetus
either at enrolment or right before their epidural. However, at delivery
there was a strong association of occipitoposterior position with epidural
analgesia. After multivariate analysis, women with an epidural were four
times as likely to have an occipitoposterior fetus at delivery.
Elizabeth Shearer, MEd, MPH1 References Go to:
1. Stremler, R, Hodnett, E, Petryshen, P, et al. Randomized controlled
trial of handsandknees positioning for occipitoposterior position in labor.
Birth 2005;32: 243–251.
2. Lieberman, E, Davidson, K, LeeParritz, A, Shearer, E. Changes in
fetal position during labor and their association with epidural analgesia.
Obstet Gynecol 2005;105: 974–982.