Cephalic presentation

The movement of the fetus to cephalic presentation is called head engagement. It occurs in the third trimester. In head engagement, the fetal head descends into the pelvic cavity so that only a small part (or none) of it can be felt abdominally. The perineum and cervix are further flattened and the head may be felt vaginally. Head engagement is known colloquially as the baby drop, and in natural medicine as the lightening because of the release of pressure on the upper abdomen and renewed ease in breathing. However, it severely reduces bladder capacity resulting in a need to void more frequently. ==Classification==

In the vertex presentation, the head is flexed and the occiput leads the way. This is the most common configuration and seen at term in 95% of singletons. The prevalence of the persistent occiput posterior is given as 4.7%. Face presentation , 1792 Factors that predispose to face presentation are prematurity, macrosomia, anencephaly and other malformations, cephalopelvic disproportion, and polyhydramnios. In an uncomplicated face presentation, duration of labor is not altered. Perinatal losses with face presentation occur with traumatic version and extraction and midforceps procedures Face presentations are classified according to the position of the chin (mentum): • Left Mento-Anterior (LMA), Left Mento-Posterior (LMP), Left Mento-Transverse (LMT) • Right Mento-Anterior (RMA), Right Mento-Posterior (RMP), Right Mento-Transverse (RMT) Brow presentation While some consider the brow presentation as an intermediate stage towards the face presentation, ==Reasons for predominance==

The piriform (pear-shaped) morphology of the uterus has been given as the major cause for the finding that most singletons favor the cephalic presentation at term. The fundus is larger and thus a fetus will adapt its position so that the bulkier and more movable podalic pole makes use of it, while the head moves to the opposite site. Factors that influence this positioning include the gestational age (earlier in gestation breech presentations are more common as the head is relatively bigger), size of the head, malformations, amount of amniotic fluid, presence of multiple gestations, presence of tumors, and others. ==Diagnosis==

Usually performing the Leopold maneuvers will demonstrate the presentation and possibly the position of the fetus. Ultrasound examination delivers the precise diagnosis and may indicate possible causes of a malpresentation. On vaginal examination, the leading part of the fetus becomes identifiable after the amniotic sac has been broken and the head is descending in the pelvis. ==Management==

Many factors determine the optimal way to deliver a baby. A vertex presentation is the ideal situation for a vaginal birth, although occiput posterior positions tend to proceed more slowly, often requiring intervention in the form of forceps, vacuum extraction, or caesarean section. ==References==