A Quick Synopsis of AFP's "Methods for Cervical Ripening and Induction of Labor"

Methods for Cervical Ripening and Induction of Labor
JOSIE L. TENORE, M.D., S.M., Northwestern University Medical School, Chicago, Illinois
Am Fam Physician. 2003 May 15;67(10):2123-2128.
http://www.aafp.org/afp/2003/0515/p2123.pdf

     Induction of labor is the artificial creation of uterine contractions, cervical effacement and dilation.  It is used when the cervix is "unfavorable". Cervical assessment is done using the Bishop score. Up to three points are given to each of the following categories:
Position
Consistency of cervix
Cervical effacement
Dilation %
Station
Patients with preeclampsia or previous vaginal deliveries get extra points. Patients with postdate pregnancy, nulliparity, or PPROM will lose points. A patient with a score less than 6 will usually need cervical ripening. 
     Herbs have had a history of being beneficial for induction. Black haw and black cohosh may have a uterine tonic effect. Blue cohosh is described as being able to stimulate uterine contractions. Red raspberry leaves can increase uterine contractions after labor has begun. The role of herbs have not been studied and the effectiveness is uncertain.
     Sexual intercourse and breast stimulation may help with labor. Nipple stimulation will increase oxytocin. Semen contains prostaglandins. The actual effectiveness lacks support.
     Mechanical modalities include hygroscopic dilators and balloon devices. The idea is that the increase pressure in the uterus will stimulate prostaglandins. Studies showed that both methods are effective for ripening. 
     Stripping the membranes will increase prostaglandin A2 and F2a, which aid in dilation. The method is associated with a lower dose of oxytocin needed, but does not appear to have any other clinical benefit. Risks include infection, rupture, and bleeding. Amniotomy can increase prostaglandin but also has no noticeable benefit in labor. 
     Pharmacologic prostaglandins are effective in cervical ripening. They dilate the cervix and cause uterine contraction. Cervidil and Prepidil are the featured medications in this article. They will increase the rate of a successful delivery. Misoprostol is a PGE1 analog. It is safe and effective when given at the proper dosage. Patients with a previous CS will be at increased risk of uterine rupture if on Misoprostol.  Misoprostol use causes a lower incidence of CS, lower need for oxytocin, and higher incidence of delivery. Mifepristone is an antiprogesterone agent, which inhibits the inhibition of uterine contraction by progesterone. It works well for  vaginal delivery. Relaxin is a hormone which promotes ripening. Studies are insufficient for relaxin at this time. Oxytocin stimulates uterine contraction through a pathway that increases calcium levels. Low dose and high doses are equally effective.