Biomechanism of Birth: less flexed head posterior position

1. Biomechanism of Birth: Less
Flexed Head Posterior Position
Name: Suryansh Pandey
Group 1430

2. Normal Mechanism of Birth
Stages of Labor
• The normal mechanism of
birth involves three stages
of labor. The first stage is
the longest and involves the
onset of labor until full
cervical dilation. The second
stage is the pushing stage,
where the baby moves
through the birth canal. The
third stage is the delivery of
the placenta.
Fetal Position
• The fetal position during birth is
important for the normal
mechanism of birth. The most
common position is the occiput
anterior position, where the
baby's head is down and facing
the mother's back. This position
allows the baby to move through
the birth canal more easily.
However, in some cases, the baby
may be in a less flexed head
posterior position, which can
make birth more difficult.

4. What is Less Flexed Head Posterior
Position?
• In a normal delivery, the baby's
head is flexed and tucked in
towards the chest, with the occiput
(back of the head) presenting first.
However, in some cases, the baby
may present with a less flexed head
and a posterior position, meaning
that the occiput is towards the
mother's back instead of towards
her pubic bone. This can make the
delivery more challenging and
increase the risk of complications

5. THE MECHANISM OF LABOR
• Engagement– the mechanism by
which biparietal diameter of the fetal
head passes through the pelvic inlet.
• The leading point – is a place on the
presenting part that first passes
through all pelvic planes and appears
from the pelvic outlet.
• The point of fixation –is a point on
the presenting part around which
rotation happens.
• The diameter and circumference of
the presenting part – the least
dimensions of the presenting part
that passes through all pelvic planes.

6. Occiput Posterior Position labor
mechanism
• Head flexion.
• The leading point will be at the
midpoint between fontanels.
• Posterior internal head rotation &
additional flexion of the head with
the base of the forehead around
lower margin of symphysis pubis.
The point of fixation is base of the
forehead.
• External rotation of the head and
internal rotation of the shoulders.
• Diameter is the occipito-frontal
and the circumference 11.5cm

7. Occiput posterior position vertex
presentation
• During vaginal examination only
posterior fontanel can be palpated,
seldom – posterior angle of the
anterior fontanel.
• Fixation points are forehead and
suboccipital area.
• Head is crowning by the
suboccipitofrontal (middle-oblique)
diameter (10 cm) circumference
33cm.
• Caput succedaneum is located on the
area of the vertex.

8. Factors Contributing to Less Flexed
Head Posterior Position
• Maternal factors such as a
narrow pelvis or an abnormal
shape of the pelvis
• Fetal factors such as a larger-
than-average head or abnormal
fetal position
• Prolonged labor or inadequate
contractions, which can cause
the baby to shift position

9. Challenges and Risks Associated with
Less Flexed Head Posterior Position
• Increased risk of prolonged labor, which
can lead to exhaustion and increased risk
of infection
• Increased risk of fetal distress or birth
injury, such as a brachial plexus injury or
cerebral palsy
• Increased risk of perineal tears or other
birth trauma for the mother
• Increased Risk of Instrumental Delivery
such as forceps or vacuum extraction,
which can increase the risk of injury to
both the mother and baby.

10. Management of Less Flexed Head
Posterior Position
• Pelvic Rocking: The mother is asked to get on
her hands and knees and rock her pelvis back
and forth. This helps to encourage the baby to
rotate and move into a more favorable
position.
• Rebozo Sifting: This technique involves the use
of a long scarf or shawl to gently lift and
support the mother's belly while she rocks
back and forth on her hands and knees. This
can help to shift the baby's position and
encourage rotation.
• Side-Lying Release: The mother is asked to lie
on her side with a pillow between her knees
and her top leg bent. This helps to open up the
pelvis and encourage the baby to rotate and
move into a more favorable position.

11. Thank You