Examining the effect of maternal obesity on outcome of labor induction in patients with preeclampsia

Challenges in timing and mode of delivery in morbidly obese women

Globally obesity is increasing especially in the reproductive age group. Pregnant women with obesity have higher complication and intervention rates. They are also at increased risk of stillbirth and intrapartum complications. Although organisations like NICE, RCOG, ACOG and WHO have published guidelines and recommendations on care of pregnant women with obesity the evidence from which Grade A recommendations can be made on timing and how to deliver is limited. The current advice is therefore to have discussions with the woman on risks to help her make an informed decision about timing, place, and mode of delivery. Obesity is an independent risk factor for pregnancy complications including diabetes, hypertension and macrosomia. In those with these complications, the timing of delivery is often influenced by the severity of the complication. As an independent factor, population based observational studies in obese women have shown an increase in the risk of stillbirth. This risk increases linearly with weight from overweight through to class II obesity, but then rises sharply in those with class III obesity by at least 10-fold beyond 42 weeks when compared to normal weight women. This risk of stillbirth is notably higher in obese women from 34 weeks onwards compared to normal weight women. One modifiable risk factor for stillbirth as shown from various cohorts of pregnant women is prolonged pregnancy. Research has linked obesity to prolonged pregnancy. Although the exact mechanism is yet unknown some have linked this to maternal dysregulation of the hypothalamic pituitary adrenal axis leading to hormonal imbalance delaying parturition. For these women the two dilemmas are when and how best to deliver. In this review, we examine the evidence and make recommendations on the timing and mode of delivery in women with obesity. For class I obese women there are no differences in outcome with regards to timing and mode of delivery when compared to lean weight women. However, for class II and III obesity, planned induction or caesarean sections may be associated with a lower perinatal morbidity and mortality although this may be associated with an increased in maternal morbidity especially in class III obesity. Studies have shown that delivery by 39 weeks is associated with lower perinatal mortality compared to delivering after in these women. On balance the evidence would favour planned delivery (induction or caesarean section) before 40 weeks of gestation. In the morbidly obese, apart from the standard lower transverse skin incision for CS, there is evidence that a supraumbilical transverse incision may reduce morbidity but is less cosmetic. Irrespective of the option adopted, it is important to discuss the pros and cons of each.

Effects of labor induction in obesity with delayed pregnancy: A retrospective study based on Chinese obese primipara

OBJECTIVE

To test the hypothesis that obese primiparous women with an unfavorable cervix in delayed pregnancy may experience a worse induction of labor.

STUDY DESIGN

In total, 467 primiparas with poor cervical condition and delayed pregnancy (gestational age [GA]: >40weeks) were divided into an obese primiparas group (body mass index [BMI] >30kg/m²; n=166) and a non-obese primiparas group (BMI < 30kg/m²; (n=301). Labor was induced by various methods, double balloon, dinoprostone inserts, and amniotomy combined with oxytocin depending on the Bishop score. Experimental data were analyzed by Statistical Product Service Solutions (SPSS).

RESULTS

BMI in the obese primiparas group was higher than in the non-obese group (33.91 ± 2.67 versus 24.09 ± 5.78, p<0.001), and there were significant differences in uterine tone and duration of contractions between the two groups in the second stage of labour (p=0.041, p=0.026, respectively).The rate of cesarean section (CS) was significantly higher in the primiparas group (23.49% versus 12.29%; P=0.002). There was a significant difference between the two groups in terms of the duration of time to vaginal delivery (VD) (18h versus 8h; P <0.001) while the duration until VD in the obese primiparas group within 12 hours and 24 hours was significantly longer (P <0.001). After adjusting for possible confounders, caesarean section rates remained high in the obese primiparas women (OR: 2.564;95%CI1.919,3.864;P<0.001). Similarly, after adjusting for the same confounding factors, obese primiparas women increased the duration until VD within 24 h by 3.598 hours.

CONCLUSION

Obese primiparas with an unfavorable cervix in delayed pregnancy have a significantly higher risk of CS and a longer duration until VD than non-obese primiparas during labor induction.

Outcomes of Elective Induction of Labor versus Expectant Management among Obese Women at ≥39 Weeks

OBJECTIVE

Maternal obesity is associated with many adverse obstetric outcomes including cesarean delivery. It is unclear whether induction of labor can reduce these risks. Previous studies report conflicting results on the outcomes of elective induction of labor among obese women. This study aimed to compare maternal and neonatal outcomes between obese women undergoing elective induction of labor and those undergoing expectant management at ≥39 weeks.

STUDY DESIGN

This was a retrospective cohort study from the Consortium on Safe Labor of obese women (defined by prepregnancy body mass index≥ 30kg/m²) with singleton gestations at ≥39 weeks without medical comorbidities from 2002 through 2008. Women scheduled for medically indicated induction of labor were excluded. The primary outcome of cesarean delivery was compared between obese women undergoing elective induction of labor and expectant management during 39th, 40th, and 41st weeks using univariable and multivariable analyses, stratifying by parity.

RESULTS

In all, 7,298 nulliparous and 9,789 parous women were eligible for analysis. After controlling for potential confounders, elective induction of labor during 39th week in nulliparous and parous women was associated with lower odds of cesarean delivery (39.1 vs. 41.6%, adjusted odds ratio [OR]: 0.47, 95% confidence interval [CI]: 0.30-0.74 for nulliparous and 5.5 vs. 10.1%, adjusted OR: 0.34, 95% CI: 0.20-0.61 for parous women) compared with expectant management. Elective induction of labor during 40th and 41st weeks was not associated with lower odds of cesarean delivery. In addition, macrosomia was reduced in nulliparous women undergoing elective induction of labor during the 40th week (12.1 vs. 18.5%, adjusted OR: 0.56, 95% CI: 0.35-0.87) and in parous women undergoing elective induction of labor during 39th (11.6 vs. 17.6%, adjusted OR: 0.50, 95% CI: 0.38-0.66) and 40th weeks (16.4 vs. 22.2%, adjusted OR: 0.53, 95% CI: 0.36-0.78).

CONCLUSION

Elective induction of labor at 39 weeks, when compared with expectant management, was associated with lower cesarean deliveries in obese nulliparous and parous women.

Prognostic models in obstetrics: available, but far from applicable

Health care provision is increasingly focused on the prediction of patients' individual risk for developing a particular health outcome in planning further tests and treatments. There has been a steady increase in the development and publication of prognostic models for various maternal and fetal outcomes in obstetrics. We undertook a systematic review to give an overview of the current status of available prognostic models in obstetrics in the context of their potential advantages and the process of developing and validating models. Important aspects to consider when assessing a prognostic model are discussed and recommendations on how to proceed on this within the obstetric domain are given. We searched MEDLINE (up to July 2012) for articles developing prognostic models in obstetrics. We identified 177 papers that reported the development of 263 prognostic models for 40 different outcomes. The most frequently predicted outcomes were preeclampsia (n = 69), preterm delivery (n = 63), mode of delivery (n = 22), gestational hypertension (n = 11), and small-for-gestational-age infants (n = 10). The performance of newer models was generally not better than that of older models predicting the same outcome. The most important measures of predictive accuracy (ie, a model's discrimination and calibration) were often (82.9%, 218/263) not both assessed. Very few developed models were validated in data other than the development data (8.7%, 23/263). Only two-thirds of the papers (62.4%, 164/263) presented the model such that validation in other populations was possible, and the clinical applicability was discussed in only 11.0% (29/263). The impact of developed models on clinical practice was unknown. We identified a large number of prognostic models in obstetrics, but there is relatively little evidence about their performance, impact, and usefulness in clinical practice so that at this point, clinical implementation cannot be recommended. New efforts should be directed toward evaluating the performance and impact of the existing models.

Induction of labor in the obese patient

Obese women are at an increased risk of antepartum pregnancy complications and are therefore more likely to require an induction of labor than normal weight women. They also have an increased rate of failing an induction of labor, a rate that rises significantly with increasing body mass index, and subsequent surgical and neonatal complications of an intrapartum cesarean delivery. This increase in induction failure may be due to differences in the myometrium of obese women resulting in decreased contraction strength. There have been only a few studies comparing the efficacy of the various cervical ripening agents in obese women and at this point no recommendation can be made as to what method may result in the greatest chance of a successful induction.

Clinical parameters for prediction of successful labor induction after application of intravaginal dinoprostone in nulliparous Chinese women

BACKGROUND

The aim of this study was to compare the possible clinical parameters for prediction of successful labor induction in Chinese nulliparous women.

MATERIAL/METHODS

A retrospective, observational trial of labor induction was performed, using a single dose of 10 mg controlled-release dinoprostone for preinduction cervical ripening in 127 nulliparous women (gestational age 38-42 weeks, singleton cephalic presentation). The characteristics of the women with successful labor induction (defined as vaginal delivery achieved on the day of admission; n=80) and failed labor induction (n=47) were compared.

RESULTS

The main differences observed between the groups were gravidity (P<0.05), induction-active labor interval (5.16±2.98 vs. 8.40±3.41; P<0.05) and birth weight (3421.11±368.14 vs. 3566.36±345.16; P<0.05). Logistic regression demonstrated that gravidity (P<0.05) and induction-active labor interval (P<0.05), but not Bishop score, were significant and independent contributing factors for successful labor induction. In the receiver operating characteristic curves for the prediction of successful labor induction, the best cut-off value for gravidity was 3 (95% confidence interval [CI] 0.64-0.83, P=0.000), and the best cut-off value for the induction-active labor interval was 7.96 (95%CI 0.66-0.85, P=0.000).

CONCLUSIONS

Less gravidity and shorter induction-active labor interval predict successful labor induction with reasonable accuracy.