New possibilities of predicting the outcome of induced labor

Background: In modern obstetrics, induced labor is one of the generally recognized methods of terminating pregnancy. Most publications note that the main indications for labor induction are a pregnancy period of more than 287 days, premature rupture of membranes, and extragenital pathology. However, data on the results of induction are contradictory. Along with studies indicating improved pregnancy and labor outcomes with the use of induction, opposite data have been published on an increase in the frequency of cesarean sections and instrumental assistance during childbirth. A favorable outcome of spontaneous and induced labor depends on the readiness of the pregnant woman’s body for childbirth. In human reproduction, the leading role of the immune system in carrying a pregnancy and initiating labor has been determined. Markers of these complex immunological events are the body’s reactions that occur as a local and systemic inflammatory response. The preliminary inflammatory process, developing in the cervix, leads to its remodeling before labor. The activity of this process can be used to judge the readiness of the pregnant woman’s body for labor. Determination of total glycosaminoglycans (GAGs) in cervical mucus, the level of which reflects the activity of preliminary inflammation in the cervix, is a non-invasive method for diagnosing readiness for labor and, accordingly, an effective response to labor induction. The level of total glycosaminoglycans in cervical mucus before labor induction allows predicting an unfavorable outcome of labor - an emergency cesarean section.

Objective: Determination of total GAG level in cervical mucus that predict the outcome of induced labor.

Materials and methods: An open prospective study was conducted involving 118 women with full-term pregnancy who delivered in the healthcare institution «Clinical Maternity Hospital of Minsk Region». Using the spectrophotometric method and calculation formulas the concentration of total glycosaminoglycans (GAGs) in the cervical mucus of pregnant women was determined before and after pre-induction of labor with drugs or mechanical means, as well as in pregnant women with term labor before the spontaneous onset of labor. The total GAGs levels in the cervical mucus were used to assess the outcomes of labor – completion through the natural birth canal or emergency cesarean section.

Results: The concentration of total glycosaminoglycans in the cervical mucus of pregnant women at the time of spontaneous onset of physiological labor has an average value of 2.7 g/l in the interval of 7 days before the onset of labor. Low levels of total GAGs in the cervical mucus of pregnant women before preinduction of labor, regardless of the chosen method, predict the risk of labor ending in cesarean section due to complications for the mother and/or fetus. In induced labor ending in cesarean section, the concentration of total GAGs in the cervical mucus before preinduction was 2 times lower than in the case of labor ending in vaginal delivery (p=0.039). In the case of cervical preparation by mechanical means, the risk of cesarean section before preinduction (1–24 hours) was demonstrated by the level of total GAGs in the cervical mucus of 2.0 g/L or less when using laminaria, and 0.2 g/L or less when using a Foley catheter. When pre-induction of labor was performed with a drug (dinoprostone gel for vaginal administration), the completion of induced labor by cesarean section was associated with the level of total GAGs in cervical mucus of 1.4 g/l or less, determined 4–6 hours after the introduction of the inducer.

Conclusion: Low levels of total GAGs before and after pre-induction of labor with drugs or mechanical means indicate the likelihood of complications in induced labor and their completion by surgery. Caesarean section in this situation is an emergency.