Stages of Labor
Labor is defined as progressive dilation of the uterine cervix in conjunction with regular contractions. This definition, therefore, excludes Braxton-Hicks contractions or “false labor” in which the contractions are not sufficient in strength or organization to cause cervical dilation. Labor is a continuous process but is commonly divided into three stages.
First Stage of Labor
The first stage of labor is the time interval between the onset of labor
and complete dilation. It is commonly subdivided into the latent phase
and active phase.
The latent phase is the period of slow cervical change and infrequent contraction. The duration of the latent phase of labor is highly variable, possibly lasting weeks. During this time the obstetrician or midwife will frequently monitor the pregnant woman. Hospitalization is not usually indicated during latent labor unless other conditions are present such as rupture of membranes, preterm gestation, or planned induction.
The active phase of labor is the period of rapid cervical change and frequent contractions. The active phase usually starts at 3 to 4 cm of dilation and ends with complete dilation. A woman in active labor is admitted to a Labor and Delivery Unit within a hospital for close fetal monitoring and management of labor. Labor and Delivery Unit nurses are specially trained to work with the obstetricians, midwifes, anesthesiologist, and pediatricians.
The duration of the active phase is dependent on multiple factors. These factors include the parity of woman with first pregnancies typically having a longer active phase, size and shape of the pelvis, size of the fetus, and contraction strength and frequency. Management of labor involves accounting for all these variables along with fetal monitoring to determine the optimal allowable time for the active phase. If indicated because of fetal indication or an unsuccessful active phase the obstetrician will recommend a Cesarean section delivery.
Second Stage of Labor
The second stage of labor is the interval between full dilation and the
delivery of the infant. The second stage of labor is when the pregnant
patient pushes with each contraction to aid in the descent of the infant.
The duration of the second stage is also predicated by the same factors
mentioned with the active phase of labor. The obstetrician or midwife
utilizes various delivery techniques in order to reduce the risk of fetal
distress, shoulder dystocia, and perineal trauma. Upon delivery, the infant’s
nose and mouth are suctioned to prevent fluid aspiration and the umbilical
cord is clamped and cut.
Third Stage of Labor
The third stage of labor is the delivery of the placenta. Although not
as climactic as the delivery of the infant, it is an important stage nonetheless.
Complete delivery of the placenta allows for uterine shrinkage and reduction
of blood loss.