‘Optimal Fetal Positioning‘ (OFP) is a theory developed by a midwife, Jean Sutton,
and Pauline Scott, an antenatal teacher, who found that the mother’s
position and movement could influence the way her baby lay in the womb
in the final weeks of pregnancy. Many difficult labors result from
‘malpresentation’, where the baby’s position makes it hard for the head
to move through the pelvis, so changing the way the baby lies could
make birth easier for mother and child.
Here is a picture of a vertex baby. Head down and facing the mom's back, this is the easiest position for birth.

I am also including the chart below that shows the presentation view
from the outlet. My son was Face First, LMT, left mentum transverse.
This is considered to be a physically impossible presentation for
vaginal delivery and the occurrence is extremely rare.

The ‘occiput anterior‘
position is ideal for birth – it means that the baby is lined up so as
to fit through your pelvis as easily as possible. The baby is head
down, facing your back, with his back on one side of the front of your
tummy. In this position, the baby’s head is easily ‘flexed’, ie his
chin tucked onto his chest, so that the smallest part of his head will
be applied to the cervix first. The diameter of his head which has to
fit through the pelvis is approximately 9.5 cm, and the circumference
approximately 27.5cm. The position is usually ‘Left Occiput Anterior’
or LOA – occasionally the baby may be Right Occiput Anterior or ROA.
Gail Tully, creater of www.spinningbabies.com
is a midwife who is very knowledgable in OFP and who helped me
understand my situation better, created this to help explain
positioning:

SO, how to achieve optimal fetal positioning? Very simply actually.
First, posture. Gail Tully and Jean Sutton say no furniture! Sit indian style in the floor, this helps open your pelvis and release your pelvic floor. Use a birth ball for better posture. “Rest Smart” Nap or sleep in positions that let your baby’s back settle in your “hammock.”
To help facilitate good positioning, pelvic tilts should
be done daily and several times a day. Walking and prenatal yoga also
help with positioning by moving your hips and pelvis, stretching things
out and encouraging the baby to engage in an occiput anterior position.
Remember though, HEAD DOWN IS NOT ENOUGH! Babies can be head down but
OP (face up) or asynclitic which can cause really long hard back
labors. Read here to learn more.
So you may need to figure out what position your baby is in to begin with. Belly Mapping can
help with that. By feeling where the baby is, where you feel movement,
where the heart beat is, the shape of moms tummy, we can figure out how
the baby is positioned. It isn’t hard to do at all. Once you learn the
postition, you can then focus on improving it or changing it
completely. Sometimes we know before labor even starts that the baby is
OP and can get the baby to rotate. There are also ways to get a breech baby to turn.
Every pregnant woman should know this information. It is so vital in
ensuring that you have the best labor and delivery possible. Sometimes
breech babies won’t turn and sometimes OP babies stay OP but by
learning OFP techniques you are at least giving yourself a chance to
make a difference.
If you are pregnant here’s a list to help with positioning:
Pelvic tilts 20 each 3x per day
Sit indian style
Do not recline
Use a birth ball
Take at least a 20 minute walk every day
Learn what position your baby is in now
Learn what to do to improve the position
Learn what to do to keep the baby in that position
Get help if you are unsure
Get help if the baby won’t move
Good luck!
EDIT: Here is some information sent to me by Ann Tumblin concerning OP babies and epidural use.
Epidural Analgesia Linked to Increased Risk of Occiput- Posterior Babies
Lieberman, E., Davidson, K., Lee-Parritz, A., & Shearer, E. (2005).
Changes in fetal position during labor and their association with
epidural analgesia. Obstetrics & Gynecology, 105 (5, Part 1),
974-982. [Abstract]
Summary: This prospective cohort study used periodic ultrasound
examinations during labor to evaluate changes in fetal position and
their relationship with epidural analgesia. The researchers sought to
determine whether epidural analgesia is responsible for higher rates of
fetal malposition (occiput-posterior (OP) or occiput transverse (OT))
or whether women experiencing labor with a malpositioned baby have more
painful labors and are therefore more likely to request epidural pain
relief. A total of 1562 nulliparous, low-risk pregnant women were
enrolled in the study.
The researchers found that the position of the baby (occiput
anterior (OA), OP or OT) at the time of enrollment (in the early part
of active labor) predicted position at birth poorly. For instance, of
the women with an OP baby at birth, only 31% had a baby in the OP
position at the initial ultrasound scan. Similarly, sonograms done
later in labor were also poor predictors of position at birth. The data
demonstrated that changes in fetal position were common during labor,
with 36% of participants having an OP baby at the time of at least one
scan. More than one-half of the women who gave birth to a baby in the
OP position never had an OP baby at any ultrasound assessment in labor.
Overall, 79.8% of babies were born in the OA position, 8.1% were OT,
and 12.2% were OP at birth.
Epidural analgesia was strongly associated with delivery from the OP
position: 12.9% of women with epidurals gave birth to babies in the OP
position versus 3.3% of women without epidurals (relative risk 4.0, 95%
CI 1.5-10.5). Transverse position was not related to epidural use. In a
statistical model that controlled for various medical and obstetric
factors that could affect outcomes, epidural use was still associated
with a 4-fold increase in the risk of OP birth.
The data suggest that the association between epidurals and OP
babies is not because women in labor with an OP baby are more likely to
request an epidural. Women who received epidurals were no more likely
to have OP babies at prior to or at the time that the epidural was
administered. Furthermore, women with OP babies in labor or at birth
reported the same degree of pain as those with OA or OT babies and were
no more likely to report “back labor,” which is commonly thought to be
related to the OP position. Finally, women with OP or OT babies at
birth were much more likely that those with babies in the OA position
to give birth by cesarean section, with 6.3% of OA babies born by
c-section versus 64.7% of OP and 73.8% of OT babies (p<.001).
Significance for Normal Birth: Epidural use increases the risk of
instrumental (forceps or vacuum) delivery in first-time mothers.
Experts have proposed various reasons for this association, including
diminished urge to push and changes in the tone of the pelvic floor
muscles that inhibit proper rotation of the fetal head. Letting the
epidural “wear off” has been thought to increase the likelihood of
unassisted vaginal birth, however, this systematic review calls into
question that common practice.
In normal birth, there are complex hormonal shifts that help labor
progress and facilitate delivery. The laboring woman produces natural
endorphins that help her manage the pain of labor. Her ability to move
freely and assume a variety of positions while pushing work in concert
with these hormonal changes. Epidural analgesia numbs the sensations of
birth, and the production of natural endorphins ceases as a result of
the disruption of the hormonal feedback system. When the epidural is
discontinued, the woman’s pain returns but her natural endorphins may
remain diminished and therefore her pain may be greater than if the
epidural had not been given in the first place. Furthermore, when an
epidural is administered, the woman is usually confined to bed and
attached to fetal monitors and an intravenous line. The woman and
provider may become accustomed to laboring in the bed attached to
machines. When the epidural is discontinued the restrictions! on her
movement may persist. Under these conditions, it is likely that the
impact of an epidural on normal birth may outlast the epidural itself.
EDIT: Ann Tumblin also sent me this regarding OP (face up) babies. It was done by Penny Simkin
who is basically the mother of all doulas. It is very informative so if
you have ever had an OP baby and are nervous about it a second time, I
highly recommend you taking a look at it.