Cumulative oxytocin dose in spontaneous labour - Adverse postpartum outcomes, childbirth experience, and breastfeeding.

OBJECTIVES: This study aimed to determine the association between the total cumulative oxytocin dose during labour and adverse postpartum outcomes, childbirth experience and breastfeeding in term primiparous women with spontaneous onset of labour. STUDY DESIGN: A prospective observational multicentre study, including 1395 women with spontaneous labour, in seven hospitals in Southeast Sweden. Multivariable logistic regression (Crude Odds Ratios (OR) and adjusted OR (aOR) for relevant confounders) was used to analyze the association between oxytocin dose and postpartum outcomes. The exposure was the cumulative oxytocin dose during labour, classified in percentiles (<25th, 25-75th, >75th). The outcomes were occurrence of obstetric anal sphincter injury, postpartum haemorrhage (blood loss > 1000 ml), Apgar score < 7 at five minutes, umbilical cord arterial pH, postpartum bladder overdistension, exclusive breastfeeding at one week and three months, and the woman's perceived birth experience. RESULTS: Women receiving high amounts (>75th percentile, >4370 mU) of oxytocin infusion during labour had an increased risk of postpartum haemorrhage (OR 2.73 (1.78-4.19)), an overdistended bladder (OR 2.19 (1.11-4.31)), an infant with an Apgar score < 7 at five minutes (OR 2.89 (1.27-6.57)), a negative birth experience (OR 1.83 (1.25-2.69)), and a decreased chance of exclusive breastfeeding at one week (OR 0.63 (0.41-0.96)). After adjusting for confounders, all outcomes remained statistically significant except risk of low Apgar score and chance of exclusive breastfeeding. CONCLUSION: In women with high cumulative oxytocin dose during labour prompt, and prophylactic administration of uterotonics after delivery of the placenta should be considered to reduce the risk of postpartum haemorrhage. The risk for bladder overdistension can be reduced by implementing routines for observation for signs of bladder filling in the early postpartum period, as well as routine use of bladder scans post micturition to assess for successful bladder emptying. As women's birth experience have a major impact on their future mental health, should be routinely assessed postpartum, and support should be offered to women with negative experiences.

The association between maternal body mass index and serial plasma oxytocin levels during labor.

OBJECTIVE: To evaluate the association between maternal body mass index (BMI) and plasma oxytocin (OT) levels at different OT infusion rates in labor. METHODS: A prospective observational study analyzing serial plasma samples in laboring women with OT infusion. The women were categorized into three groups, women with non-obesity (BMI 18.5-29.9, n = 12), obesity (BMI 30.0-34.9, n = 13), and morbid obesity (BMI ≥ 35.0, n = 15). Plasma OT was analyzed using tandem mass spectrometry. RESULTS: Except for a low positive correlation between OT levels and BMI and significantly increased plasma OT levels in women with morbid obesity at the OT infusion rate of 3.3 mU/min, no significant differences in OT levels between the BMI groups were found. Further, the inter-individual differences in OT levels were large and no dose-dependent increase of OT levels was seen. CONCLUSIONS: Other factors than plasma OT levels may be more likely to determine the clinical response of OT infusion in women with obesity. Perhaps the observed clinical need and individual response would be a better predictor of plasma OT levels than a pre-determined OT infusion rate. The OT dosage guidelines for labor augmentation should be individualized according to clinical response rather than generalized. TRIAL REGISTRATION: Clinical trial registration: ClinicalTrials.gov ID NCT04093479.

Maternal body mass index and oxytocin in augmentation of labour in nulliparous women: a prospective observational study.

OBJECTIVE: To evaluate oxytocin use for augmentation of labour in relation to body mass index (BMI) on admission to the labour ward, focusing on cumulative oxytocin dose and maximum rate of oxytocin infusion during the first stage of labour. DESIGN: Prospective observational study. SETTING: Seven hospitals in Sweden. PARTICIPANTS: 1097 nulliparous women with singleton cephalic presentation pregnancy, ≥37 weeks of gestation, spontaneous onset of labour and treatment with oxytocin infusion for labour augmentation. The study population was classified into three BMI subgroups on admission to the labour ward: normal weight (18.5-24.9), overweight (25.0-29.9) and obese (≥30.0). The cumulative oxytocin dose was measured from the start of oxytocin infusion until the neonate was born. PRIMARY OUTCOME: Cumulative oxytocin dose. SECONDARY OUTCOME: Maximum rate of oxytocin infusion during the active phase of first stage of labour. RESULTS: The mean cumulative oxytocin dose increased in the BMI groups (normal weight 2278 mU, overweight 3108 mU and obese 4082 mU (p<0.0001)). However, when adjusted for the confounders (cervical dilatation when oxytocin infusion was started, fetal birth weight, epidural analgesia), the significant difference was no longer seen. The maximum oxytocin infusion rate during the first stage of labour differed significantly in the BMI groups when adjusted for the confounding factors individually but not when adjusted for all three factors simultaneously. In addition, the maximum oxytocin infusion rate was significantly higher in women with emergency caesarean section compared with women with vaginal delivery. CONCLUSIONS: Women with increasing BMI with augmentation of labour received a higher cumulative oxytocin dose and had a higher maximum oxytocin infusion rate during first stage of labour, however, when adjusted for relevant confounders, the difference was no longer seen. In the future, the guidelines for augmentation of labour with oxytocin infusion might be reconsidered and include modifications related to BMI.

Obstetric Outcomes in Adolescents Related to Body Mass Index and Compared with Low-Risk Adult Women.

OBJECTIVE: To evaluate in adolescents the association between body mass index (BMI) and obstetric outcomes and to determine whether the outcomes in the BMI groups of adolescents differ from those of a low-risk population of adult women. MATERIALS AND METHODS: This is a nationwide population-based register study. Obstetric outcomes of 31,386 singleton primiparous adolescents were evaluated in relation to BMI classes. Furthermore, the outcomes of the adolescents and 178,844 normal weight, nonsmoking, singleton primiparous women, 25-29 years old with no known comorbidity, defined as standard women, were compared. Multiple logistic regression models were used. Results are presented as crude odds ratios (ORs) or adjusted ORs and with a 95% confidence interval. RESULTS: Compared with normal weight adolescents, obese adolescents had a lower chance of a normal vaginal delivery (VD)-76% versus 85% [adjusted OR 0.61 (0.55-0.68)], a higher risk for acute cesarean section (CS)-8.9% versus 4.5% [adjusted OR 2.45 (2.08-2.88)], and stillbirth-0.7% versus 0.2% [adjusted OR 3.17 (1.74-5.77)]. Compared with standard women, overweight adolescents had a higher chance of a normal VD-82% versus 75% [crude OR 1.53 (1.44-1.64)] and a lower risk for acute CS-6.3% versus 7.1% [crude OR 0.85 (0.76-0.95)]. Obese adolescents had a lower risk for instrumental VD-8% versus 13% [crude OR 0.61 (0.53-0.71)] and obstetric anal sphincter injury-1% versus 3% [crude OR 0.38 (0.26-0.57)]. CONCLUSION: Several adverse obstetric outcomes were obesity related among adolescents. Overweight adolescents seemed to have better obstetric outcomes than standard women, something to consider when optimizing resources for women during pregnancy and delivery.