‘A baby’s skull is squeezed during vaginal birth’

A baby’s skull bones overlap during vaginal birth, says study. (Source: Getty Images)

Childbirth is of course physically demanding for the mother but a new study has shown how it also impacts the baby’s body and distorts it in the case of vaginal delivery.

How a baby’s head changes shape during delivery

The research, published in PLOS One, studied the degree to which a baby’s skull bones ride over each other by recording MRI scans before and during labour. As per the findings of the study, the baby’s head becomes the shape of sugarloaf–an elongated cone with a rounded tip at one end–to get through the pelvis. The softer regions at the top of the head are known to accommodate being squeezed through the birth canal and allow room for the brain to grow during infancy. This skull squeezing is known as foetal head molding.

In the study, it was found that the skull bones did not overlap prior to labour but once it began, they were visibly overlapped. In most babies, the skull returned to their pre-labour shapes soon after birth.

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Not just head compression, babies undergo a massive transition during birth and delivery to maximise their chances of survival as they move out of the supported environment of the uterus to an independent existence. Here are some of the other changes:

Sudden increase in oxygen

The developing baby initially manages on relatively low levels of oxygen in the uterus. Once the baby is born, the blood goes through the placenta to get rid of waste and pick up oxygen and nutrients from the mother. The child is exposed to suddenly higher oxygen levels after birth, which is why the newborn has systems ramped up to cope with the excess oxygen levels. One of the protective mechanisms seen in many infants is temporary yellowing of the skin or mild jaundice.

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Before birth, most of the baby’s blood circulation passes through the placenta but it stops after delivery. The blood from the heart now needs to redirect through the newly expanded lungs, as explained in another research in Resuscitation journal.

All changes in the baby may not take place

All changes, however, may not take place if the baby is born prematurely. Premature babies may have trouble opening up their lungs to redirect blood flow or may have difficulty exchanging oxygen and other gases in the lungs, as mentioned by professor of paediatrics and child health research Ian Wright in an article. Most premature babies, according to Wright, boost from the onset of labour that triggers the biological signals to tell the baby to get ready for being born.

What happens in Caesarean delivery?

Babies born by C-section without labour may not transition to the outside world as smoothly as compared to others, and are more at risk of respiratory problems. As per another paper, Timing of Elective Caesarean Section at Term, delivery any week earlier than 40 weeks roughly doubles the risk of neonatal unit admission for babies.