The active labor commences when the uterine contractions come in more frequently and with stronger intensity. On internal examination, the cervix opens to 4 to 10 cm. During this phase, the dilation of the cervix is faster and more predictable compared to the latent phase. The healthcare provider is able to estimate the progress of labor until full dilatation, because during the active phase, the cervix typically dilates at a rate of 1.2 to 1.5 cm per hour.
If the dilation of the cervix does not progress as expected, the healthcare provider will re-assess the power and frequency of contractions, the dimension of the pelvis, the position of the baby’s head, and size of the baby. If after assessment and close observation, there really is not much change in the dilation of the cervix, the mother is primed for abdominal delivery. Another factor noted when doing internal examination is the descent of the baby’s head.
Cervical Dilation During Labor and Delivery
To give an example, suppose a woman gets admitted for labor pains. On internal examination, the cervix is measured to be dilated at 7cm. The physician then estimates that in 2 hours, the cervix will be fully opened at 10 cm (considering she previously delivered vaginally two years ago). This is based on the expected rate of cervical dilation at 1.5 cm per hour. The pelvic exam was repeated after an hour. The cervical dilation did not change but the frequency and strength of the contractions were deemed adequate. The doctor then closely observed the progress of labor for another hour. Still, there was no change in cervical dilation. On re-assessment of the baby’s estimated weight, it was said to be a lot bigger than her previous baby. In such a scenario, the doctor will counsel the woman regarding the likelihood of an abdominal delivery because cervical dilation was arrested.