Women with term pregnancies whose labor started spontaneously. Spontaneous labor is determined by either spontaneous rupture of membranes at term and/or powerful, regular uterine contractions that cause cervical change. Women will be admitted to labor ward after initial assessment via transperineal ultrasonography. Labor augmentation will be performed for women with inadequate uterine contractions, i.e. contractions measuring less than Montevideo units, irregular weak uterine contractions. Analgesia will be provided via administration of 50 mg intramuscular meperidine at 2 hour intervals as required. Amniotomy will be performed for women with adequate cervical dilatation and fetal head-descent. Transperineal ultrasonography will be performed at irregular intervals to assess cervical dilatation, angle of progression and fetal head position. After birth, birth time, birth weight, APGAR scores, degree of perineal trauma, episiotomy use will be recorded.

Women with term pregnancies who are induced for birth before the onset of spontaneous labor. Labor will be induced with either oxytocin infusion for women with high Bishop score, or labor will be induced with dinoprostone pessary for women requiring cervical ripening, i.e. poor. Women will be admitted to labor ward after initial assessment via transperineal ultrasonography. Analgesia will be provided via administration of 50 mg intramuscular meperidine at 2 hour intervals as required. Amniotomy will be performed for women with adequate cervical dilatation and fetal head-descent. Transperineal ultrasonography will be performed at irregular intervals to assess cervical dilatation, angle of progression and fetal head position. After birth, birth time, birth weight, APGAR scores, degree of perineal trauma, episiotomy use will be recorded.

Assessment of cervical dilatation, angle of progression and head position via transperineal ultrasonography

Duration of active labor will be calculated in minutes, in a reverse fashion, beginning from time of birth and going back to first time of measurement.

Rate of cervical dilatation assessment will be measured in millimetres/hour in a reverse fashion beginning from the time when maximum dilatation is achieved and going back to time of first measurement.

Rate of angle of progression advancement will be measured in metric degree in a reverse fashion beginning from the last measurement taken and going back to first measurement taken.

Effect of amniotomy on the duration of labor will be assessed in minutes by analysing the different time points in different labor processes when amniotomy has taken place.