Natural childbirth and homebirth advocates have a distressing habit of seizing on lies and repeating them over and over again to convince themselves and others that they are true. One currently popular lie is that “breech is a variation of normal.”
Here’s a little hint: If it dramatically increases the risk of death, then it is NOT a variation of normal. And breech presentation dramatically increases the risk of death. Contrast that with true variations of normal like left-handedness vs. right-handedness, which have no bearing on health or life expectancy.
To understand why breech presentation dramatically increases the risk of death, it is helpful to review some basic principles of childbirth. At term, the baby’s head is usually the largest part of the baby. That means that if the head fits, the rest of the baby should follow without difficult (shoulder dystocia is an exception). Moreover, the bones of the fetal skull are not fused and can slide past each other, allowing “molding” of the fetal head letting it squeeze through the pelvis. In the breech presentation, the head is still the biggest part of the baby, but now it is coming last and there is no chance for it to mold to squeeze through the pelvis. There is a high risk that the head will be trapped, often resulting in the death of the baby.
Breech babies and their mothers differ in substantial ways from the rest of the population. Breech babies are far more likely to have congenital anomalies, particularly anomalies like hydrocephalus that increase the size of the fetal head. In other words, the baby ends up breech because the head is too large to properly fit in the pelvis. Mothers who carry breech babies often have uterine anomalies that distort the shape of the uterus. In other words, the baby ends up breech because the bottom of the uterus cannot accommodate the fetal head.
The risks of labor differ substantially for breech babies. Typically, the head fills the cervix as it is dilating, making it impossible for the cord to prolapse (fall out), a condition that routinely ends in death. In contrast, the breech, being smaller, does not fill the cervix, making cord prolapse far more likely. In addition, in contrast to vaginal delivery where the baby’s arms are pressed to its sides, the arms of a breech baby may end up over its head. One or both can end up behind the head crossing the neck. This is known as nuchal arms. A baby with nuchal arms cannot be delivered because the diameter of the head plus the arm(s) is too big to fit through the pelvis. Unless the provider can move the arm(s) from behind the head, the baby will die.
In addition, there’s more than one kind of breech. To say that the baby is in the breech presentation means only that the bottom of the baby is coming first. The bottom may refer to the buttocks or the feet (more dangerous). The breech baby may have its chin to its chest or it may be facing upward (more dangerous).
Indeed, in studies that purported to show the safety of vaginal breech delivery, all the babies in the complete or footling breech presentations are excluded. All babies with extended heads (looking up) are excluded. All large babies are excluded. All women with a small pelvis are excluded. So much for “breech” being a variation of normal.
How dramatically does breech presentation increase the risk of perinatal death? The experience in Norway, before and after the C-section rate for breech had risen precipitously, is representative of the risks. According to Secular trends in peri- and neonatal mortality in breech presentation; Norway 1967–1994 by Albrechtsen et al.:
… The extended peri- and neonatal mortality rate in breech presentation births declined during the study period from 9.2% in 1967–76 to 5.5% in 1977–86 and to 3.0% in 1987–94. The highest relative risk of mortality in breech presentation versus the total birth population was observed in intrapartum death and in mortality less than 24 hours after delivery…
During the study period, the overall rate of perinatal mortality declined due to advances in obstetrics and neonatology. In addition, the C-section rate rose dramatically. Both contributed to the overall decline in mortality from breech delivery. But as the following graph shows. C-section for breech uniformly led to better outcomes.
The bottom line is that, any way you look at it, breech is NOT a variation of normal. Breech babies have a higher incidence of congenital anomalies and their mothers have a higher incidence of uterine anomalies. Breech babies are at much higher risk for cord prolapse and encounter complications like nuchal arms and trapped heads that simply do not occur in head first deliveries. Most importantly, any baby in the breech position has a dramatically higher risk of death.
A variation that kills babies is not a variation of normal.
