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To investigate the impact of severe obesity (body mass index [BMI] ≥35 kg/mExploratory, blinded analysis of a randomised controlled trial cohort.Two labour wards, one in a university tertiary hospital and one in a central hospital.In all, 686 parturients with singleton pregnancies, gestational age ≥37 weeks, fetus in cephalic presentation, and intrauterine tocodynamometry during labour. [Correction added on 6 June 2022, after first online publication: the number of parturients has been corrected to 686.] METHODS: Uterine contractile activity was assessed as intrauterine pressure, frequency of contractions and basal tonus of uterine muscle. The use of oxytocin and cervical dilatation were recorded simultaneously.Primary outcome: uterine contractile activity.use of oxytocin, labour outcomes.Obese parturients reached intrauterine pressure ≥200 Montevideo units (MVU) during the first stage of labour more often than leaner parturients; 62% vs 49%; odds ratio [OR] 1.67 (95% CI 1.05-2.67) and had higher basal tone of uterine muscle. However, obese parturients without previous vaginal delivery were not able to reach the active stage of labour as often as leaner ones, and their vaginal delivery success rate was lower. If a parturient had had previous vaginal delivery, obesity did not influence uterine activity, nor was there a risk of caesarean section. Doses and total consumption of oxytocin did not differ between BMI groups.Obese nulliparas have stronger uterine contractile activity than leaner ones, but they more often fail to reach the active phase of labour and their vaginal delivery success rate is lower.Despite higher strength of uterine contractions among obese parturients, they reach the active stage of labour less often than leaner ones.

Objective To investigate whether the use of intrauterine tocodynamometry versus external tocodynamometry (IT versus ET) during labour reduces operative deliveries and improves newborn outcome. As IT provides more accurate information on labour contractions, the hypothesis was that it may more appropriately guide oxytocin use than ET. Design Randomised controlled trial. Setting Two labour wards, in a university tertiary hospital and a central hospital. Population A total of 1504 parturients with singleton pregnancies, gestational age ≥37 weeks and fetus in cephalic position: 269 women with uterine scars, 889 nulliparas and 346 parous women with oxytocin augmentation. Methods Participants underwent IT (n = 736) or ET (n = 768) during the active first stage of labour. Main outcome measures Primary outcome: rate of operative deliveries. Secondary outcomes duration of labour, amount of oxytocin given, adverse neonatal outcomes. Results Operative delivery rates were 26.9% (IT) and 25.9% (ET) (odds ratio 1.05, 95% CI 0.84-1.32, P = 0.663). The ET to IT conversion rate was 31%. We found no differences in secondary outcomes (IT versus ET). IT reduced oxytocin use during labours with signs of fetal distress, and trial of labour after caesarean section. Conclusions IT did not reduce the rate of operative deliveries, use of oxytocin, or adverse neonatal outcomes, and it did not shorten labour duration. Tweetable abstract IT (versus ET) reduced oxytocin use in high-risk labours but did not influence operative delivery rate or adverse neonatal outcomes.

Background Purpose of this study was to investigate differences between primiparous term pregnancies, one leading to vaginal delivery (VD) and the other to acute cesarean section (CS) due to labor dystocia in the first stage of labor. We particularly wanted to assess the influence of body mass index (BMI) on CS risk. Methods A retrospective case-control study in a tertiary delivery unit with 5200 deliveries annually. Cases were 296 term primiparous women whose intended vaginal labor ended in acute CS because of dystocia. Controls were primiparas with successful vaginal delivery VD (n = 302). The data were retrieved from medical records. Multiple logistic regression analyses were used to assess the associations between BMI and covariates on labor dystocia. Results In the cases ending with acute CS, women were older (OR 1.06 [1.03–1.10]), shorter (OR 0.94 [0.91–0.96]) and more often had a chronic disease (OR 1.60 [1.1–2.29]). In this group fetal malposition (OR 42.0 [19.2–91.9]) and chorioamnionitis (OR 10.9 [5.01–23.6]) were more common, labor was less often in an active phase (OR 3.37 [2.38–4.76]) and the cervix was not as well ripened (1.5 vs. 2.5 cm, OR 0.57 [0.48–0.67] on arrival at the birth unit. BMI was higher in the dystocia group (24.1 vs. 22.6 kg/m2, p < 0.001), and rising maternal pre-pregnancy BMI had a strong association with dystocia risk. If BMI increased by 1 kg/m2, the risk of CS was 10% elevated. Among obese primiparas, premature rupture of membranes, chorioamnionitis and induction of labor were more common. Their labors were less often in an active phase at hospital admission. Severely obese primiparas (BMI ≥ 35 kg/m2) had 4 hours longer labor than normal-weight parturients. Conclusions Labor dystocia is a multifactorial phenomenon in which the possibility to ameliorate the condition via medical treatment is limited. Hospital admission at an advanced stage of labor is recommended. Pre-pregnancy weight control in the population at reproductive age is essential, as a high BMI is strongly associated with labor dystocia.