Your baby’s head is the largest part of her body, so when a baby delivers head-first, it usually goes without saying that the rest of the baby follows. But there are many variations from this standard head-first position, such as breech presentation, transverse lie, and shoulder-first. And even if your baby presents head-first, her face can be pointing down, up, or even face-first. These little surprises keep obstetricians and midwives on alert with each seemingly routine delivery.
So what do these various positions mean to you? Here’s a primer on baby presentation basics.
In the head-first category, the shape of the mother’s pelvis can determine which way the head is placed. The most common way is face-down, allowing the easiest measurement to clear the pelvis. This position is especially helpful because the head can pivot up against the pubic bone, allowing the chin’s appearance to finish the delivery of the full head.
Face-up or occipital posterior (back of the head down) is a more difficult delivery because the baby can’t flex the head on exit. It’s like delivering a baby that weights a full pound more. It’s not impossible, but it’s more difficult to effectively push, and the pushing stage of labor can last longer than usual.
If your baby’s head is sideways, this is called transverse position. Usually the head can be gently rotated by the obstetrician to face-down for a normal delivery.
Asynclitism, or a head-first position wherein the head is tilted to the right or left from the midline, is yet another birth presentation. Many people feel that an epidural given before the head has descended well into the pelvis causes the maternal muscles that normally guide the head down correctly to become relaxed, resulting in a sloppy, unguided descent. It’s a hard positioning to work with and can lead to a C-section.
Traditional Breech Presentation
Breech refers to a feet- or buttocks-first presentation. This is a real thinking obstetrician’s dilemma, because, as mentioned above, the largest part of the baby is the head. So delivery of the feet or buttocks first creates a scenario where larger and larger parts of the baby have to clear the pelvis. In other words, if the head won’t fit out in a head-first baby, delivery can be effected via second choice–the C-section. But in a breech delivery, if the head won’t fit out, the rest of the baby already has. The cord is out as well and is compressed in the birth canal on it’s way up to the placenta. This is an emergency with such a bad outcome that most obstetricians feel that a breech presentation necessitates a C-section.
So why do some babies come out head first and others breech? Babies tend to seek the most comfortable position in their mothers’ wombs. If the largest part of the baby is the head, then the baby will fidget and maneuver until the head gravitates to the largest space in the uterus. The most generous space is usually the lower uterus; and usually at 32 weeks this position will stick.
A breech usually occurs when there’s a problem and the lower uterus is not the biggest space. For instance, a low-lying placenta can occupy enough space so that the there is more space higher in the uterus. Also, congenital abnormalities can make other parts of the baby the biggest body part, meaning that part will become the lowermost presenting part. In fact, in my training it was always a warning to check for abnormalities when there was a breech presentation.
Other Breech Presentations
In a frank breech, the buttocks are first. In a footling breech, one or both feet are first–the single-footling breech or the double-footling breech. The difference depends on whether the knees are bent or not. In both situations, the hips are flexed, but if the knees are straight, then the lower legs, along with the thighs, are bent over the baby’s abdomen, resulting in the frank breech. If the knees are bent, then the feet are positioned back toward the cervix and the outside world.
Thankfully, most breeches are in that position for unknown reasons. Mostly normal breech babies are delivered by C-section, putting to rest the fear of congenital problems. Some brave obstetricians (I’m not one of them) deliver these babies, but this isn’t acceptable unless the baby is estimated to be at least a pound less than the mother’s previous largest baby, the baby is a frank breech, and the maternal pelvic measurements are generous.
Any breech that is a first baby should still be born by C-section, because it’s easier to explain a possibly unnecessary C-section than to explain a baby that was traumatized by the too large after-coming head. Plus, many OBs believe that even successful vaginal deliveries of breech babies result in what are called soft neurological signs (not brain damage, but Attention Deficit Disorder, dyslexia, hyperactivity, and the like).
Every Which Way But…
Occasionally I’ll encounter a baby that’s in a crazy position, such as transverse (whole body sideways) or shoulder-first. C-section is the safest way to address this malpresentation. It is just common sense: the forces of labor will crunch a baby that’s not pointing straight down.
And Then There’s Twins!
If you think the placenta can crowd out an adequate space, imagine what an extra baby does! Twins will compete for the most comfortable space, but usually there’s a membrane that will separate them and favor one to be lower. The big risk here, though, is a breech baby that’s first, compared to the head-first second twin. In this positioning, the head of Baby One (the breech) may sit just above the head of Baby Two (the higher of the babies).
When labor ensues for a vaginal delivery, it’s possible to have the horror of interlocking heads. Needless to say, a breech/head-first presentation of twins necessitates a C-section. But head-first/head-first twins can deliver vaginally, as can head-first/breech. (Except, once again, when an OB just doesn’t feel comfortable with this type of delivery; as is the case, once again, with me.)
There can be a considerable wait sometimes for Baby Two to descend, and with this there’s the possibility of a prolapsed cord, which could cut off oxygen to this twin. Because of this, although not always, doctors will opt to deliver twins via C-sections.
The Happy, Healthy Delivery
Delivery of a baby (or babies) requires knowledge of the baby’s position. With third- and fourth-generation antibiotics and advanced surgical technique, the risk to the mother from a C-section is now outweighed by the benefit to the baby when there’s positioning that would make vaginal delivery hazardous.
In contrast to the dangerous times of just a generation ago, we no longer need to seek heroic vaginal deliveries for these babies. And even using this way out, the C-section rate can still be kept low by waiting for proper descent of the baby’s head into the maternal pelvis before administration of an epidural.