Effects of analgesia pain relief during entire labor on maternal and neonatal outcomes under new partogram

Objective To explore the effects of whole-stage labor analgesia on maternal and neonatal outcomes after the implementation of the new partogram. Methods A retrospective cohort study was performed in Peking University First Hospital. From June to December 2016, 907 nulliparae with full-term singleton cephalic pregnancies that were expected to deliver vaginally and adhered to the new partogram were selected as the study group, and 982 cases that adhered to the old partogram (Friedman standard) from June to December 2012 were selected as the control group. Maternal basic characteristics and analgesic, obstetric and neonatal data were collected. Maternal and neonatal outcomes between the two groups were analyzed with independent sample t-test, rank sum test or Chi-square test (Fisher's exact test). Results (1) Maternal age and the proportion of gravidas of advanced maternal age in the study group were both higher than those in the control group [(30.2±3.0) vs (29.6±2.9) years, t=3.823; 8.2% (74/907) vs 4.2% (41/982), χ2=13.087; both P<0.001]. No statistically significant difference in the other basic characteristics was found between the two groups. (2) Women in the study group had significantly smaller cervical dilatation [M(P25-P75)] than that in the control group when analgesia was commenced [2(1-2) vs 2(1-3) cm, Z=-3.752]. The intensity of pain quantified with numerical rating scale (NRS) before analgesia, and during the second stage of labor in the study group were less than that in the control group [8(8-9) vs 8(8-10) points, Z=-14.441; 5(4-5) vs 6(5-7) points, Z=-16.495]. The study group had longer median duration of analgesia than the control group [520(340-750) vs 300(200-453) min, Z=-17.801, P<0.001]. The overall dose of analgesics in injection pump in the study group was significantly higher compared with that used in the control group [68 (35-84) vs 30 (18-48) ml, Z=-18.004, P<0.001]. However, there was no significant difference in the incidence of analgesia-related complications (hypotension, accidental dura puncture, lower extremity numbness, pruritus and urinary retention) between the two groups. (3) The study group showed a higher percentage of spontaneous vaginal delivery, and a lower rate of converted cesarean section compared with the control group [71.8% (651/907) vs 63.2% (621/982), χ2=15.623; 13.6% (123/907) vs 20.5% (201/982), χ2=18.831; both P<0.001]. The study group had lower forceps-assisted vaginal delivery rate than the control group without statistically significant difference [14.8% (133/907) vs 15.3% (150/982), χ2=0.093, P=0.797]. The duration of the first, second and third stage of labor in the study group were all significantly longer than that of the control group [680 (470-900) vs 480 (360-660) min, Z=-12.490; 56 (31-89) vs 37 (24-58) min, Z=-9.964; 7 (5-10) vs 6 (5-8) min, Z=-6.673; all P<0.001]. Women in the study group had a lower rate of artificial rupture of membranes when comparing with the control group [55.2% (501/907) vs 63.2% (621/982), χ2=12.516, P<0.001]. The incidence of fever, pathologically confirmed infection and postpartum hemorrhage were significantly higher in the study group than that in the control group [10.8% (98/907) vs 6.4% (63/982), χ2=11.652; 9.6% (87/907) vs 3.7% (36/982), χ2=27.201; 12.6% (114/907) vs 5.7% (56/982), χ2=27.144; all P<0.05]. There was no significant difference in the rate of oxytocin use during labor or blood transfusion between the two groups. (4) Compared with the control group, the proportion of cesarean section due to arrested active stage of labor in the study group was significantly lower [5.7% (7/123) vs 50.2% (101/201), χ2=68.173, P<0.05], but the incidences of cesarean section due to intrauterine infection and relative cephalopelvic disproportion were higher in the study group [61.0% (75/123) vs 30.8% (62/201), χ2=2.680; 20.3% (25/123) vs 8.0% (16/201), χ2=10.555; both P<0.05]. There was no significant difference in the proportion of fetal distress or other indications for cesarean section between the two groups. (5) There was no significant difference between the two groups in birth weight, macrosomia, fetal distress, neonatal asphyxia, or the proportion of neonatal intensive care unit admission. Conclusions After the implementation of the new partogram, analgesic pain relief covering the whole labor prolongs the average analgesic time and reduces the rate of cesarean section due to arrested active stage of labor. Although the risk of postpartum hemorrhage is slightly increased, analgesia itself does not pose additional risks on forceps-assisted delivery, maternal blood transfusion and neonatal asphyxia. Key words: Labor, obstetric; Analgesia, epidural; Labor stage, second; Analgesia, obstetrical; Cesarean section