Predicting factors on cervical ripening and response to induction in women pregnant over 37 weeks

Induction of labor is conducted in special fetal or maternal conditions. Labor is induced in about 20% of women. The AIM of this study was realizing the relationship between some factors including cervical ripening and also response to induction so we could predict the induction outcome better.

The present prospective study was based on 101 pregnancy cases admitted to the labor ward in Urmia from March 2010 until December 2010. Maternal age ranged from 17 to 41 years and the gestational age between 37 to 42 weeks according to an ultrasound or reliable last menstrual period, as criteria of study inclusion. After admission, patients had a vaginal speculum for Preterm Premature Rupture of Membranes (PPROM), Abdominal ultrasonography for biometry and Amniotic Fluid Index (AFI), transperineal ultrasonography for measuring fetal head distance to maternal perineum, and vaginal ultrasonography for measuring cervical length and posterior angle of fetal head with cervix were undergone. Bishop score was assigned to another person. Labor was induced by administering either intravaginal misoprostol (25 microgram every six hours for a Bishop score lower than 7) or intravenous oxytocin (low dose regimen for a Bishop score equal to or more than 7).

Misoprostol was used for 75 patients and 26 patients had induction of labor with low dose oxytocin. Eighty one patients had Normal Vaginal Delivery (NVD) while 20 were delivered via Cesarean Section. For cervical ripening, Bishop Score (p<0.001), cervical length (p=0.04) and parity (p=0.06) were predicting factors. The cervical posterior angle p=0.02 had a predicting role in natural delivery.

The cervical posterior angle was a predicting factor for natural delivery. Although cervical length, Body Mass Index (BMI), and parity were not predicting factors for natural delivery; these factors were good predictors for cervical ripening.