Analysis of the factors affecting the duration of the latent period from the moment of prelabor rupture of membranes to the onset of labor

Abstract

Introduction. Premature rupture of membranes during full-term pregnancy represents an increased risk of septic complications for both the mother and the fetus due to the prolongation of the latency period, the period from the discharge of amniotic fluid till the onset of labor.
 Purpose of the study: to assess the factors affecting the duration of the latent period (from the moment of discharge of amniotic fluid to the development of labor) during full-term pregnancy.
 Materials and methods. A prospective analysis of the labor of 136 patients with premature rupture of membranes and full-term pregnancy (37-42 weeks) of low and moderate risk groups, without contraindications for vaginal birth was carried out. Patients with Bishops cervical score less than or equal to 7 points made up the main group (70 pregnant women). Patients with mature cervix were included in the comparison group (66 cases). The analysis of the duration of the latent period was carried out with the use of correlation and regression analysis.
 Results. The time from the moment of discharge of amniotic fluid to the onset of regular labor in the group with a cervix 7 Bishop points was 7.82 4.53 hours, while in the group with a cervix 8 Bishop points it was 4.4 3.23 hours (T = 5.02; p 0.001). The most significant effect on the duration of the latency period was the assessment of the cervix according to Bishop scale (r = 0.48; p 0.001), the gestational age was in the second place (r = 0.23; p = 0.08). In patients who didnt take mifepristone, the main factors influencing the duration of the latency interval were fetal weight (r = 0.31; p = 0.004) and gestational age (r = 0.29; p = 0.008); the increase in these parameters led to the decrease in the latency interval. Women who received 200 mg mifepristone in labour had a significant positive correlation with maternal age (r = 0.36; p = 0.04), negative with maternal weight (r = 0.42; p = 0.01) and cervical Bishop score (r = 0.48; p = 0.004). Women in labor with the longest latency interval, who received mifepristone in a daily dosage of 400 mg, have an inverse correlation for the gestational age (r = 0.39; p = 0.09), connection with the degree of cervical maturity, age, constitutional features, gestational age was not revealed.
 Conclusion. The main predictors of the duration of the latency period of premature rupture of membranes at full-term pregnancy were the degree of cervical maturity according to Bishop scale, gestational age and fetal weight at birth.