New 3-D images show the degree of stress placed on a baby’s skull as it moves through the birth canal, leaving even scientists surprised.
Infants are born with soft skulls which helps get them through the relatively narrow birth canal, but the details of fetal head molding were not totally clear. Now, thanks to a new study published in PLOS One, medical experts used 3-D MRI to capture detailed images of babies’ skulls and brains during advanced stages of labour, according to Live Science. Their findings suggest that infants’ heads undergo considerable stress during birth, much more than previously thought.
Twenty-seven pregnant women received MRI scans before they gave birth, and of those, seven agreed to be scanned during the second stage of labour—the period between when the cervix has dilated to 10 centimetres and the baby is born. Pre-labour and mid-labour images helped the researchers determine that all seven babies experienced fetal head molding-- the skull overlapped, to varying degrees, during the birthing process. Infants’ skulls are thus comprised of several bony sections, held together by fibrous materials called sutures, that eventually fuse as the baby grows outside the womb. Still, the researchers were surprised by just how much babies’ heads were squishing as they moved through the birth canal, according to Live Science.
The skulls of five of the babies under observation quickly returned to their pre-birth state, but changes persisted in two of the babies. This could be due to differences in the elasticity of the skull bones and the supporting fibrous material, among other factors. Two of the three babies with the largest degree of head molding still needed to be delivered via C-section, indicating that mothers may not always be able to give birth vaginally, “even when significant fetal molding occurs,” the study authors note.
“This definition does not take into consideration the ability of the fetal head to deform,” the researchers explain. “If the fetal head’s compliance is high, the skull and brain may undergo significant deformation as the birth canal is crossed, and the child's condition at birth may not be good.”
Revelations about the stresses that come with fetal head molding might also explain why some babies are born with retinal and brain hemorrhages, the latter of which can lead to major complications such as cerebral palsy. The researchers say the high quality imaging could inform efforts to develop a “more realistic simulation of delivery” that will help medical experts predict which mothers are at risk of running into biomechanical complications during childbirth—and intervene accordingly.