A new study has found that mothers who delivered vaginally
compared to caesarean section delivery (CSD) were significantly
more responsive to the cry of their own baby, identified through
MRI brain scans two to four weeks after delivery.
The results of the study, to be published today in The Journal
of Child Psychology and Psychiatry, suggest that vaginal delivery
(VD) mothers are more sensitive to own baby-cry in the regions
of the brain that are believed to regulate emotions, motivation
and habitual behaviours.
CSD is a surgical procedure, in which delivery occurs via
incisions in the abdominal and uterine wall. It is considered
necessary under some conditions to protect the health or survival
of infant or mother, but it is controversially linked with
postpartum depression. In the US the occurrence of CSD has
increased steeply from 4.5% of all deliveries in 1965 to a
recent high in 2006 of 29.1%.
The critical capacity of adults to develop the thoughts and
behaviours needed for parents to care successfully for their
newborn infants is supported by specific brain circuits and
a range of hormones. The experience of childbirth by VD compared
with CSD uniquely involves the pulsatile release of oxytocin
from the posterior pituitary, uterine contractions and vagino-cervical
stimulation. Oxytocin is a key mediator of maternal behaviour
"We wondered which brain areas would be less active
in parents who delivered by caesarean section, given that
this mode of delivery has been associated with decreased maternal
behaviours in animal models, and a trend for increased postpartum
depression in humans," said lead author Dr. James Swain,
Child Study Centre, Yale University. "Our results support
the theory that variations in delivery conditions such as
with caesarean section, which alters the neurohormonal experiences
of childbirth, might decrease the responsiveness of the human
maternal brain in the early postpartum."
The researchers also looked into the brain areas affected
by delivery conditions and found relationships between brain
activity and measures of mood suggesting that some of the
same brain regions may help regulate postpartum mood.
"As more women opt to wait until they are older to have
children, and by association be more likely to have a caesarean
section delivery, these results are important because they
could provide better understanding of the basic neurophysiology
and psychology of parent-infant attachment," said Swain.
"This work could lead to early detection of families
at risk for postpartum depression and attachment problems
and form a model for testing interventions."