Baby Positions
What is a malpositioned baby?
Babies and mothers are designed for birth. Nature intends for babies to be in a vertical position, curled a bit, to fit through the mother's pelvis in the smallest tube-shape the baby can get into during labor. When a baby isn't in this "vertical, tube-shape" the fit can be difficult or impossible. That's when I'd say the baby is in a "malposition."
Oblique lie
The baby is oblique when baby's head is in the mother's hip. The baby's body and head are diagonal, not vertical and not horizontal (transverse lie). This is fine for a second twin. But oblique is not an optimal fetal position for a singleton baby after 30 weeks gestation.
Right Occiput Posterior
Baby is head down and the back is to the side- The right side. This position can be deceptively reassuring.
Whether the ROP baby has a hard time rotating and descending through the pelvis has to do with the usual things: balance in the mother's soft tissues, symmetry in the pelvic floor, pelvic size and shape, and how well the baby's head is tucked... oh yes, and whether the mother labors actively, upright when she isn't resting and free to move and eat in labor.
There are some tips the midwife, nurse and doctor can use to tell whether the baby is right occiput posterior or right occiput transverse (lateral). The ROP baby may need a longer time for fetal rotation in labor. Again, this depends on the previous list of factors.
I found this comment on a forum, the mother is uninformed about right-sided babies and the midwife may not know how to tell if the baby is ROP or ROT or ROA. "Last update was that the midwife thinks baby is occiput *right* but I don't think the right/left is too big of a deal. At least the midwife thinks baby is no longer posterior."
How to tell if the baby is ROP or ROT and does it really matter?
Will Baby fit?
Head size is less important when it comes to fitting through the pelvis than is the angle of the baby's head. A posterior baby will present a bigger head circumference and can sometimes get stuck in a pelvis that the same baby could have fit through if anterior. See what to do to reduce incorrect diagnosis of CephaloPelvic Disproportion.
Head down is not enough!
Many parents think that as long as the baby is head down in the womb the baby is ready for birth. Head down is only half the story.
It is a big relief to find out
the baby is not breech (buttocks coming through the pelvis before the
head is born). Especially when so many breech babies are born by cesarean these days and so few doctors and midwives understand spontaneous breech birth. But being head down is only the first step. For the best chance at a natural birth there is more preparation. Baby should have his or her chin tucked by 38 weeks or so. For a first time mother, the baby is expected to engage in the pelvic brim (dip into the pelvis a bit) by 38 weeks. A second baby or more, may wait above the brim until labor begins, or even gets rolling. Then, if we can help the baby's back get to the the mother's left with baby's feet to the right side (only). Otherwise, labor often rotates the baby into a better position when women use active birthing techniques.
Asynclitism
Asynclitism means asymmetrical and is the term used when a baby’s head is tipped towards one shoulder. Early in labor this is normal and desired.
Asynclitism only becomes a problem when the head is still tipped beyond early labor. The asynclitic head has a harder time passing through the narrow part of the pelvis; the ishial spines. Labor becomes longer, and sometimes baby doesn't fit out the pelvis...Happily, we have a trick for this problem.
Occiput Posterior - OP
In this article, what is a posterior fetal position, pregnancy clues a mother can use to tell if baby is posterior, why it matters in labor, who might have an easy posterior labor and who might need more help. Click to go to What to do in a Posterior Labor.
Pregnancy may or may not show symptoms - labor may or may not be significantly effected. When labor IS effected, there is a range of what can happen.
“How can I help my baby stay anterior?"
What is "the most practical way of making sure my baby stays anterior? I've had TWO posterior babies! UGH!”
Mainly, the baby will "stay" anterior if your womb is balanced (symmetrical, not torqued or twisted) and you continue to use good maternal positioning. Positioning without releasing tension in the abdominal soft tissues and pelvic joints isn't likely to succeed in rotating a baby in pregnancy, especially for a woman with a history of posterior babies or breech, because these positions show the uterine ligaments weren't in balance before pregnancy.
Myths of occiput posterior
There are some myths about laboring with a posterior baby.
Let's start with appreciation for Penny Simkin's brave confrontation of a dogmatic trend that has arisen over the last few years. At first, I was rather surprised to hear a talk by Penny Simkin called, "The OP Fetus; How little we know." Now, the light has gone on. Parents and professionals alike have some misunderstandings about the influence of posterior presentation on labor.
For instance, "She didn't have back labor so I didn't think the baby
was posterior." Or, "We did everything we could because we tried hands
and knees position in labor."
Sometimes a midwife or doctor will say they don't pay much attention to a head down baby's position in late pregnancy because some posterior babies come out fine. Emphasis mine. Spinning Babies is about the 15-30% that need more help than strong labor and the hands and knees position.
Transverse Lie, or baby lying sideways
“Transverse Lie” means a sideways position. The baby has his head to one of his mother’s sides and the bottom across her abdomen at her other side. This is normal before, and at, 26 weeks, but by 29-30 weeks we expect babies to be head down, or at least breech.
If not, this article outlines what to do, easy ways to fix it, and what to do if they don't - read the stories, too.
The word transverse is also used in phrases describing two head down positions: Left occiput transverse (an ideal starting position) and right occiput transverse. These head down positions means baby is facing mother's hip.
Left Occiput Anterior
The left occiput anterior position is often the easiest fetal position for the start of labor.
Babies settle in the LOA position naturally when the womb is pretty well balanced. This position helps the baby be in the smallest diameter to fit the pelvis.
Click "Read LOA" to see pictures and understand more.
Right Occiput Anterior
I
believe my baby is ROA, but you talk about the
importance of the baby being LOA. You claim that LOA is the best for
chin tucking and moving through the pelvic outlet.
Dip in the Belly
"There is an indentation in my belly near my navel. Does this mean my baby is posterior?"
An indentation, or dip, near or beneath your belly button can mean a couple of things. One possibility is that the baby is posterior. The posterior baby has his or her back along the mother's back. The knees are bent and the arms are bent, usually. This makes the baby in the shape of a letter "C." The opening of the "C" is towards the mother's abdomen wall and navel. The opening can allow a "dip" in the mother's belly shape, right about the place her navel is.
Anterior Placenta
What is the effect of an anterior placenta on fetal positioning?
An anterior placenta means that the placenta is located on the front of the uterus. Most of the baby will be hidden behind it. Palpation (a hands-on exam through the skin) can be more difficult, whereas, an ultrasound can determine the baby's position pretty well.
It is a common belief that the anterior placement of the placenta causes the baby to be posterior. The fact that this is sometimes true doesn't mean it is always true. Babies can be anterior with an anterior placenta. Abdominal tone, when loosened, can allow the baby to turn away from the placenta and face the mother's back.
Chin tucking for engagement
Flexion into the brim of pelvis helps the baby fit through the pelvis. Flexion refers to the tucking of the baby’s chin, in this case. 
Flexion, or chin tucking, is even more important than starting labor with an anterior head position!
Many posterior babies can be born with natural labor, or just a bit of Pitocin, when they begin active labor with their heads tucked. Learn about both flexion and engagement here.
Occiput Transverse
Occiput Transverse (OT)
I consider ROT to be one of the posterior positions, first upon Jean Sutton's advice and also on my observations. Typically the ROT baby, and especially the first baby when ROT, will rotate to the posterior as labor proceeds. The reason is that the ROT baby more often has an extended back which then extends the head. Whether Your baby has his or her chin up depends on your pelvis, which baby this is for you, whether you labor in bed on your back or up and moving freely, how tight or symmetrical your pelvic floor may be, the amount of extension of the baby's head, and so on. A previous vaginal birth makes this position less troublesome. Fetal chin tucking regardless of parity makes the ROT (ROL) position less troublesome, too. READ a doula's story about a birth in which the baby "got stuck" for a while in the Occiput Transverse late in labor, she used inversions to prevent a cesarean.
