The true pelvis isthe bony canal through which the fetus must pass

• The true pelvisis divided into three sections: inlet, pelvic cavity and outlet

• There are four types of pelvis: gynecoid (most common), android, anthropoid and

platypelloid

o The gynecoid and the anthropoid are both favorable for vaginal birth

o The android and platypelloid are not favorable for vaginal birth

2. Fetus

• In the fetal head the parietal, frontal and occipital bones are not fused together, so the head can adjust to the narrow portions of the pelvis

• Molding– when the cranial bones overlap under pressure of the powers of labor and the demands of the pelvis

• The sutures in the skull allow for molding of the fetal head and help the clinician to identify the position of the fetal

head during vaginal exams

o NI: explain to mom that open sutures are good b/c they allow for the baby to accommodate for birth; let

them know that the head will go back to normal shape

• Fontanelles—are useful (along with the sutures) in identifying the position of the fetal head in the pelvis and

assessing the status of the newborn after birth

o Anterior fontanelle – measures 2 cm by 3 cm and permitsthe growth of the brain by remaining like that

for 18 months

o Posterior fontanelle –smaller, closes within 8-12 weeks after birth

o Fontanelles should be FLAT (normal finding)

▪ Abnormal: buldging (hematoma, fluid), orsunken (dehydration)

• Fetal attitude—refersto the relation of the fetal partsto one another

o Normal attitude of the fetus: is one moderate

flexion of the head, flexion of the arms onto the

chest and flexion of the legs into the abdomen

• Fetal lie – refersto the relationship of the spinal column of the

fetus to the spinal cord or the woman

o Vertical—the ideal position for birth

o Transverse =NOT GOOD

• Fetal presentation– the way the fetus entersthe pelvic area

which can be cephalic, breech orshoulder(head, buttocks,shoulder, foot)

o Cephalic—occurslabor and delivery are likely to proceed normally

o Vertex presentation: most favorable for vaginal births

o Other presentations: military, brow, face, and the different

malpresentations/breech

Malpresentations—confirmed with ultrasound before

labor starts or Leopold’s Maneuver

Breech and shoulder are associated with more difficultiesin

labor (known as malpresentations)

• Breech presentation – birth in which the butt or feet

are first out, the sacrum isthe landmark to be noted;

buttocks, shoulder and foot come out first!

o Frank Breech: legs are extended upward

o Footling Breech: watch for the cord! Don’t

want the cord to prolapsed

NI: preventthe cord fromgetting compressed! Do

not put back in.

o Complete Breech

o Transverse/Shoulder Lie