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.

Neonatal and maternal outcomes at early vs. full term following induction of labor; A secondary analysis of the OBLIGE randomized trial.

INTRODUCTION: Birth at early term (37+0-38+6 completed gestational weeks [GW] and additional days) is associated with adverse neonatal outcomes compared with waiting to ≥39 GW. Most studies report outcomes after elective cesarean section or a mix of all modes of births; it is unclear whether these adverse outcomes apply to early-term babies born after induction of labor (IOL). We aimed to determine, in women with a non-urgent induction indication (elective/planned >48 h in advance), if IOL at early and late term was associated with adverse neonatal and maternal outcomes compared with IOL at full term. MATERIAL AND METHODS: An observational cohort study as a secondary analysis of a multicenter randomized controlled trial of 1087 New Zealand women with a planned IOL ≥37+0 GW. Multivariable logistic regression was used to analyze neonatal and maternal outcomes in relation to gestational age; 37+0-38+6 (early term), 39+0-40+6 (full term) and ≥41+0 (late term) GW. Neonatal outcome analyses were adjusted for sex, birthweight, mode of birth and induction indication, and maternal outcome analyses for parity, age, body mass index and induction method. The primary neonatal outcome was admission to neonatal intensive care unit (NICU) for >4 hours; the primary maternal outcome was cesarean section. RESULTS: Among the 1087 participants, 266 had IOL at early term, 480 at full term, and 341 at late term. Babies born following IOL at early term had increased odds for NICU admission for >4 hours (adjusted odds ratio [aOR] 2.16, 95% confidence intervals (CI) 1.16-4.05), compared with full term. Women having IOL at early term had no difference in emergency cesarean rates but had an increased need for a second induction method (aOR 1.70, 95% CI 1.15-2.51) and spent 4 h longer from start of IOL to birth (Hodges-Lehmann estimator 4.10, 95% CI 1.33-6.95) compared with those with IOL at full term. CONCLUSIONS: IOL for a non-urgent indication at early term was associated with adverse neonatal and maternal outcomes and no benefits compared with IOL at full term. These findings support international guidelines to avoid IOL before 39 GW unless there is an evidence-based indication for earlier planned birth and will help inform women and clinicians in their decision-making about timing of IOL.

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.

Gestational diabetes mellitus and time in active labor: A population-based cohort study.

INTRODUCTION: Women with gestational diabetes mellitus (GDM) have higher rates of adverse perinatal outcomes compared with women without GDM, including an increased risk for having labor induced and for cesarean section. The findings from previous studies analyzing duration of labor in women with GDM are contradictory. The aim of the study was to evaluate the impact of GDM on time in spontaneous and induced active labor. MATERIAL AND METHODS: This was a population-based cohort study including 247 524 primiparous women who gave birth to a singleton fetus with cephalic presentation, ≥34+0 (completed gestational weeks + additional days) between January 2014 and May 2020 in Sweden. Data was obtained from the Swedish Pregnancy Register. Time in active labor was compared between women with GDM and without GDM with a spontaneous labor onset or induction of labor using Kaplan Meier survival analysis and Cox regression analysis. RESULTS: Women with GDM had significantly longer time in active labor, both with a spontaneous onset and induction of labor compared to women without GDM. Women with GDM had a decreased chance of vaginal delivery at a certain time-point compared to women without GDM, with adjusted hazard ratio of 0.92 (0.88-0.96) and 0.83 (0.76-0.90) for those with spontaneous onset and induction of labor, respectively. Women with GDM had increased risk for time in active labor ≥12 h both in spontaneous labor onset (adjusted odds ratio 1.14 [1.04-1.25]) and in induction of labor (adjusted odds ratio 1.55 [1.28-1.87]). CONCLUSIONS: Women with GDM seem to spend a longer time in active labor, both in spontaneous and induced active labor compared to women without GDM. To be able to individualize care intrapartum, there is a need for more studies demonstrating the impact of hyperglycemia during pregnancy on outcomes during childbirth.

Maternal childbirth experience and time in labor: a population-based cohort study.

A negative childbirth experience may have long term negative effects on maternal health. New international guidelines allow a slower progress of labor in the early active phase. However, a longer time in labor may influence the childbirth experience. In this population-based cohort study including 26,429 women, who gave birth from January 2016 to March 2020, the association between duration of different phases of active labor and childbirth experience was studied. The women assessed their childbirth experience by visual analogue scale (VAS) score. Data was obtained from electronic medical records. The prevalence of negative childbirth experience (VAS 1-3) was 4.9%. A significant association between longer duration of all labor phases and a negative childbirth experience was found for primi- and multipara. The adjusted odds ratio (aOR (95%CI)) of negative childbirth experience and longer time in active labor (above the 90th percentile) in primipara was 2.39 (1.98-2.90) and in multipara 2.23 (1.78-2.79). In primi-and multipara with duration of labor ≥ 12 h or ≥ 6 h the aOR (95%CI) of negative childbirth experience were 2.22 (1.91-2.58) and 1.91 (1.59-2.26) respectively. It is of great importance to identify and optimize the clinical care of women with longer time in labor to reduce the risk of negative childbirth experience and associated adverse long-term effects.

Labor dystocia and oxytocin augmentation before or after six centimeters cervical dilatation, in nulliparous women with spontaneous labor, in relation to mode of birth.

BACKGROUND: The effects of diagnosing and treating labor dystocia with oxytocin infusion at different cervical dilatations have not been fully evaluated. Therefore, we aimed to examine whether cervical dilatation at diagnosis of dystocia and initiation of oxytocin infusion at different stages of cervical dilatation were associated with mode of birth, obstetric complications and women's birthing experience. METHODS: A retrospective cohort study, including 588 nulliparous term women with spontaneous onset of labor and dystocia requiring oxytocin augmentation. The study population was divided into three groups according to cervical dilatation at diagnosis of dystocia and initiation of oxytocin-infusion (≤ 5 cm, 6-10 cm, fully dilated) with mode of birth as the primary outcome. Secondary outcomes were obstetrical and neonatal complications and women´s experience of childbirth. Statistical comparison between groups using Chi-square and ANOVA was performed. The risk of operative birth (cesarean section and instrumental birth) was assessed using binary logistic regression with suitable adjustments (maternal age, body mass index and risk assessment on admission to the labor ward). RESULTS: The cesarean section rate differed between the groups (p < 0.001); 12% in the ≤ 5 cm group, 6% in the 6-10 cm group and 0% in the fully dilated group. There was no increased risk for operative birth in the ≤ 5 cm group compared to the 6-10 cm group, adjusted OR 1.28 95%CI (0.78-2.08). The fully dilated group had a decreased risk of operative birth (adjusted OR 0.48 95%CI (0.27-0.85). The rate of a negative birthing experience was high in all groups (28.5%, 19% and 18%) but was only increased among women in the ≤ 5 cm group compared with the 6-10 cm group, adjusted OR 1.76 95%CI (1.05-2.95). CONCLUSIONS: Although no difference in the risk of operative birth was found between the ≤ 5 cm and 6-10 cm cervical dilatation-groups, the cesarean section rate was highest in women with dystocia requiring oxytocin augmentation at ≤ 5 cm cervical dilatation. This might indicate that oxytocin augmentation before 6 cm cervical dilatation could be contra-productive in preventing cesarean sections. Further, the increased risk of negative birth experience in the ≤ 5 cm group should be kept in mind to improve labor care.

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.

The effect of maternal body mass index on duration of induced labor.

INTRODUCTION: Obese primiparous women with induction of labor are at high risk for a cesarean section. There are contradictory results regarding time in induced labor in relation to maternal body mass index (BMI). It is important to characterize the course of induced labor to prevent unnecessary cesarean section. We aimed to evaluate whether the duration of labor was associated with maternal BMI in primiparous women with induction of labor. MATERIAL AND METHODS: A national retrospective cohort study, including 15 259 primiparae with a single term pregnancy, admitted for induction of labor from January 2014 to August 2017. Data were obtained from the Swedish Pregnancy Registry. Cox regression analyses were used to illustrate the association between BMI and active labor and between BMI and time from admission until start of active labor. RESULTS: Duration of active labor was shorter in underweight women and prolonged in women with BMI ≥40 kg/m2 compared with women in other BMI classes, illustrated by Cox regression graphs (P < .001). The median durations of active labor in underweight women were 6.1 and 7.4 hours in women with BMI ≥40 kg/m2 . The time from admission until start of active labor increased with maternal BMI, illustrated by Cox regression graphs (P < .001) and the median duration increased from 12.9 hours in underweight women to 22.6 hours in women with BMI ≥40 kg/m2 . The cesarean section rate in active labor increased significantly with BMI (P < .001) from 7.4% in underweight women to 22.0% in women with BMI ≥40 kg/m2 . Obese and normal weight women had similar rates of spontaneous vaginal delivery (69.9% in the total study population). CONCLUSIONS: The duration of active labor was associated with maternal BMI for underweight women and women with BMI ≥40 kg/m2 . Although women with BMI ≥40 kg/m2 who reached the active phase of labor had the same chance for a spontaneous vaginal delivery as normal weight women, the duration of active labor and the cesarean section rate were increased. The time from admission until start of active labor increased successively with maternal BMI.

Maternal plasma leptin levels in relation to the duration of the active phase of labor.

INTRODUCTION: Obese women have increased leptin levels and longer duration of labor compared with normal-weight women. Leptin has an inhibitory effect on myometrial contractility in vitro. Our purpose was to examine whether maternal leptin levels in active labor were associated with the duration of the active phase of labor. MATERIAL AND METHODS: This prospective cohort study included 914 women. Maternal blood samples were collected in active labor. The plasma-leptin concentration was obtained using a direct sandwich-based ELISA. Bivariate and multiple linear regression analyses were used to study the association between leptin levels and the duration of labor. RESULTS: A 1 ng/mL increase in maternal plasma leptin was associated with a 0.015 hour increase in duration of labor (P < .007). This association was not statistically significant in the adjusted analyses nor when analyzing nulliparous and multiparous women separately. In women with spontaneous labor (n = 766) leptin levels were not associated with an increase in duration of labor in the adjusted analyses. CONCLUSIONS: There was no significant association between leptin levels and duration of the active phase of labor. Leptin in vivo might display a similar dose-response effect on myometrial contractility as demonstrated in in vitro studies. Future studies need to explore the association between leptin levels and time in labor in obese women with high leptin levels to evaluate a possible dose-response effect.

Maternal obesity (Class I-III), gestational weight gain and maternal leptin levels during and after pregnancy: a prospective cohort study.

BACKGROUND: Maternal obesity is accompanied by maternal and fetal complications during and after pregnancy. The risks seem to increase with degree of obesity. Leptin has been suggested to play a role in the development of obesity related complications. Whether maternal leptin levels differ between obese and morbidly obese women, during and after pregnancy, have to our knowledge not been previously described. Neither has the association between maternal leptin levels and gestational weight gain in obese women. The aim was to evaluate if maternal plasma leptin levels were associated with different degrees of maternal obesity and gestational weight gain. METHODS: Prospective cohort study including women categorized as obesity class I-III (n = 343) and divided into three gestational weight gain groups (n = 304). Maternal plasma leptin was measured at gestational week 15, 29 and 10 weeks postpartum. Maternal Body Mass Index (BMI) was calculated from early pregnancy weight. Gestational weight gain was calculated using maternal weight in delivery week minus early pregnancy weight. The mean value and confidence interval of plasma-leptin were analysed with a two-way ANOVA model. Interaction effect between BMI and gestational weight gain group was tested with a two-way ANOVA model. RESULTS: The mean maternal leptin concentrations were significantly higher in women with obesity class III compared to women in obesity class I, at all times when plasma leptin were measured. The mean leptin concentrations were also significantly higher in women with obesity class II compared to women in obesity class I, except in gestational week 29. There was no difference in mean levels of plasma leptin between the gestational weight gain groups. No significant interaction between BMI and gestational weight gain group was found. CONCLUSIONS: Plasma leptin levels during and after pregnancy were associated with obesity class but not with degree of gestational weight gain. These results are in concordance with epidemiological findings where the risk of obstetric complications increases with increased maternal obesity class. The effect on obstetric outcome by degree of gestational weight gain is less pronounced than the adverse effects associated with maternal obesity.

Maternal body mass index and duration of labor.

OBJECTIVE: To evaluate whether the duration of the active phase of labor is associated with maternal body mass index (BMI), in nulliparous women with spontaneous onset of labor. STUDY DESIGN: Historical prospective cohort study including 63,829 nulliparous women with a singleton pregnancy and a spontaneous onset of labor, who delivered between January 1, 1995 and December 31, 2009. Data were collected from the Perinatal Revision South registry, a regional perinatal database in Southern Sweden. Women were categorized into six classes of BMI. Overweight and obese women were compared to normal weight women regarding duration of active labor. Adjustments were made for year of delivery, maternal age and infant birth weight. RESULTS: The median duration of labor was significantly longer in obese women (class I obesity (BMI 30-34.9) = 9.1h, class II obesity (BMI 35-39.9) = 9.2h and class III obesity (BMI > 40) = 9.8h) compared to normal-weight women (BMI 18.5-24.9) = 8.8h (p < 0.001). The risk of labor lasting more than 12h increased with increasing maternal BMI: OR 1.04 (1.01-1.06) (OR per 5-units BMI-increase).The risk of labor lasting more than 12h or emergency cesarean section within 12h, compared to vaginal deliveries within 12h, increased with increasing maternal BMI. Duration of the second stage of labor was significantly shorter in obese women: in class III obesity the median value was 0.45 h compared to normal weight women, 0.55 h (p < 0.001). CONCLUSION: In nulliparous women with a spontaneous onset of labor, duration of the active phase of labor increased significantly with increasing maternal BMI. Once obese women reach the second stage they deliver more quickly than normal weight women, which implies that the risk of prolonged labor is restricted to the first stage of labor. It is clinically important to consider the prolonged first stage of labor in obese women, for example when diagnosing first stage labor arrest, in order to optimize management of this rapidly growing at-risk group of women. Thus, it might be reasonable to adapt the considered upper limit for duration of labor, according to maternal BMI.