Why are cesarean delivery rates so high in diabetic pregnancies?

A Review of Third-Trimester Complications in Pregnancies Complicated by Diabetes Mellitus

Pregnancies affected by both pregestational and gestational diabetes mellitus carry an increased risk of adverse maternal and neonatal outcomes. While the risks associated with diabetes in pregnancy have been well documented and span across all trimesters, maternal and neonatal morbidity have been associated with select third-trimester complications. Further, modifiable risk factors have been identified that can help improve pregnancy outcomes. This review aims to examine the relationship between select third-trimester complications (large for gestational age, intrauterine fetal demise, hypertensive disorders of pregnancy, preterm birth, perineal lacerations, shoulder dystocia, and cesarean delivery) and the aforementioned modifiable risk factors, specifically glycemic control, blood pressure control, and gestational weight gain. It also highlights how early optimization of these modifiable risk factors can reduce adverse maternal, fetal, and neonatal outcomes. KEY POINTS: · Diabetes mellitus in pregnancy increases the risk of third-trimester complications.. · Modifiable risk factors exist for these complications.. · Optimizing these modifiable risk factors improves maternal and neonatal outcomes..

Cesarean delivery rates and indications in pregnancies complicated by diabetes

OBJECTIVE

Rates of pregestational (PGDM) and gestational diabetes (GDM), and their associated pregnancy complications, are rising. Pregnancies complicated by diabetes have increased cesarean delivery (CD) rates; however, there are limited data regarding the current rates of, and contributing factors to, these deliveries. The Robson Ten Group Classification System (TGCS) is a clinically relevant, standardized framework that can be used to evaluate and analyze cesarean rates. The objective of this study was to evaluate rates of, and indications for, intrapartum, unplanned CD among pregnancies complicated by diabetes, compared to normoglycemic (NG) pregnancies, in a large United States birth cohort.

METHODS

This retrospective cohort study used chart-abstracted data on births between 24 and 42 weeks' gestation at 17 hospitals that contributed to the Obstetrical Care Outcome Assessment Program database between 01/2016 and 03/2019. The CD rate for NG pregnancies, and pregnancies complicated by gestational and PGDM was calculated and compared using the Robson TGCS. The indications for intrapartum CD in patients with term, singleton, vertex gestations without a prior cesarean were then analyzed. Univariate and multivariate logistic regression models were used to compare the cesarean rate and indications for CD, between the diabetic groups and the NG group. Results were adjusted for maternal age, BMI, neonatal birth weight, and insurance status, as well as clustering by hospital.

RESULTS

A total of 86,381 pregnant people were included in the study cohort. Of these 76,272 (88.3%) were NG, 8591 (9.9%) had GDM, and 1518 (1.8%) had PGDM. Compared to NG patients, overall cesarean rates were higher in patients with GDM (40.3% vs. 29.7%; aOR 1.25, 95%CI 1.18-1.31) and PGDM (60.0% vs. 29.7%; aOR 2.53, 95%CI 2.04-3.13). This finding remained true when the cohort was restricted to term, singleton, vertex laboring patients without a prior cesarean; compared to NG patients, the cesarean rate was higher in patients with GDM (17.4% vs. 12.2%, aOR 1.37, 95%CI 1.29-1.45) and PGDM (26.0% vs. 12.2%, aOR 2.55, 95%CI 2.00-3.25). The cesarean rate for fetal indications was similar in the GDM (5.7%) and NG (4.4%) groups, while those patients with PGDM had a significantly higher rate (10.4%; aOR 2.01, 95%CI 1.43-2.83). Similarly, the rate of cesarean for labor dystocia in patients with PGDM was significantly higher than in NG patients (16.9% vs. 7.0%, and aOR 2.28, 95%CI 1.66-3.13) while patients with GDM had an intermediate rate (10.6% vs. 7.0%, aOR 1.49, 95%CI 1.40-1.57).

CONCLUSIONS

The CD rate is significantly higher in pregnancies complicated by diabetes, particularly pregestational, compared to NG pregnancies. Despite controlling for maternal factors and birth weight, pregnancies complicated by diabetes are more likely to undergo an unplanned intrapartum cesarean secondary to labor dystocia than their NG counterparts, but only pregnancies complicated by PGDM have an increased risk of cesarean for fetal indications. More research is needed to understand whether this higher cesarean rate is due to factors intrinsic to diabetes in laboring patients or is due to a difference in the way clinicians manage diabetics in labor.

Fetal anomalies in gestational diabetes mellitus and risk of fetal anomalies in relation to pre-conceptional blood sugar and glycosylated hemoglobin

BACKGROUND

The risk of fetal anomalies (FAs) is increased in infants of diabetic mothers. FAs are closely related to the glycosylated hemoglobin (HbA1c) level in pregnancy.

OBJECTIVES

To detect the prevalence of FAs in women with gestational diabetes mellitus (GDM).

MATERIAL AND METHODS

157 pregnant women with GDM were included in this study, and data from 151 women were analyzed. Beyond the regular antenatal check-up, the HbA1c was checked monthly during the antenatal follow-up. Collected data after delivery were analyzed to detect the prevalence of FAs in women with GDM and the risk of FAs in relation to the pre-conceptional blood sugar and HbA1c.

RESULTS

The FAs were recorded in 8.6% (13) of the 151 women with GDM. The recorded FAs were cardiovascular [2.6% (4)], musculoskeletal [1.3% (2)], urogenital [1.3% (2)], gastrointestinal [1.3% (2)], facial [0.7% (1)], central nervous system [0.7% (1)], and multiple FAs [0.7% (1)]. The uncontrolled pre-conceptional blood sugar significantly increased RR [RR 2.2 (95%CI: 1.7-2.9); P < 0.001], and odds of FAs [OR 17.05 (95%CI: 2.2-134.9); P = 0.007] in women with GDM. In addition, the HbA1c ≥6.5 significantly increased RR [RR 2.8 (95% CI: 2.1-3.8); P < 0.001], and odds of FAs [OR 24.8 (95% CI: 3.1-196.7); P = 0.002] in women with GDM.

CONCLUSION

In this study, the prevalence of FAs in women with GDM was 8.6%. Uncontrolled pre-conceptional blood sugar and HbA1c ≥6.5 in the first trimester significantly increased the relative risk and the odds of FAs.

Diabetes mellitus: an independent predictor of duration of prostaglandin labor induction

OBJECTIVE

The objective of this study is to analyze the association of diabetes mellitus with progress and outcomes of prostaglandin (PG) labor induction using a retrievable vaginal insert.

STUDY DESIGN

This is a secondary analysis of data collected during the Misoprostol Vaginal Insert Trial (Miso-Obs-004), a multicenter, double-blind, randomized controlled trial of women undergoing induction of labor with PGs. The duration, characteristics and outcomes of labor were compared in women with and without diabetes. Multivariable regression analysis was performed on all outcomes of interest, adjusting for differences in baseline characteristics.

RESULTS

There were 122 women with diabetes within the sample of 1275 women who delivered during their first admission. The time to reach active labor was significantly prolonged among women with diabetes compared with those without (22.0±13.0 vs 18.5±11.1, P=0.008) as was the time to delivery (30.2±15.0 vs 26.0±12.6, P=0.004). Fewer women with diabetes delivered within 36 h (adjusted odds ratio: 0.41, 95% confidence interval: 0.26 to 0.66, P=0.0003) and 48 h (adjusted odds ratio: 0.36, 95% confidence interval: 0.19 to 0.71, P=0.004). These relationships were significant after a multivariate regression analysis of baseline characteristics that adjusted for age, race, parity, body mass index, baseline modified Bishop Score, gestational age at induction and treatment group allocation.

CONCLUSION

After PG labor induction, women with diabetes took longer to reach active labor and to deliver. We emphasize that this result comes from a secondary analysis and needs confirmation with additional studies.

Prevalence of Adverse Pregnancy Outcomes, by Maternal Diabetes Status at First and Second Deliveries, Massachusetts, 1998-2007

Introduction

Understanding patterns of diabetes prevalence and diabetes-related complications across pregnancies could inform chronic disease prevention efforts. We examined adverse birth outcomes by diabetes status among women with sequential, live singleton deliveries.

Methods

We used data from the 1998–2007 Massachusetts Pregnancy to Early Life Longitudinal Data System, a population-based cohort of deliveries. We restricted the sample to sets of parity 1 and 2 deliveries. We created 8 diabetes categories using gestational diabetes mellitus (GDM) and chronic diabetes mellitus (CDM) status for the 2 deliveries. Adverse outcomes included large for gestational age (LGA), macrosomia, preterm birth, and cesarean delivery. We computed prevalence estimates for each outcome by diabetes status.

Results

We identified 133,633 women with both parity 1 and 2 deliveries. Compared with women who had no diabetes in either pregnancy, women with GDM or CDM during any pregnancy had increased risk for adverse birth outcomes; the prevalence of adverse outcomes was higher in parity 1 deliveries among women with no diabetes in parity 1 and GDM in parity 2 (for LGA [8.5% vs 15.1%], macrosomia [9.7% vs. 14.9%], cesarean delivery [24.7% vs 31.3%], and preterm birth [7.7% vs 12.9%]); and higher in parity 2 deliveries among those with GDM in parity 1 and no diabetes in parity 2 (for LGA [12.3% vs 18.2%], macrosomia [12.3% vs 17.2%], and cesarean delivery [27.0% vs 37.9%]).

Conclusions

Women with GDM during one of 2 sequential pregnancies had elevated risk for adverse outcomes in the unaffected pregnancy, whether the diabetes-affected pregnancy preceded or followed it.

Diabetes in pregnancy: timing and mode of delivery

Diabetes in pregnancy represents a risk condition for adverse maternal and feto-neonatal outcomes and many of these complications might occur during labor and delivery. In this context, the obstetrician managing women with pre-existing and gestational diabetes should consider (1) how these conditions might affect labor and delivery outcomes; (2) what are the current recommendations on management; and (3) which other factors should be considered to decide about the timing and mode of delivery. The analysis of the studies considered in this review leads to the conclusion that the decision to deliver should be primarily intended to reduce the risk of stillbirth, macrosomia, and shoulder dystocia. In this context, this review provides useful information for managing specific subgroups of diabetic women that may present overlapping risk factors, such as women with insulin-requiring diabetes and/or obesity and/or prenatal suspicion of macrosomic fetus. To date, the lack of definitive evidences and the complexity of the problem suggest that the "appropriate" clinical management should be customized according with the clinical condition, the type and mode of intervention, its consequences on outcomes, and considering the woman's consent and informed decisions.

Elective induction of labor in women with gestational diabetes mellitus: an intervention that modifies the risk of cesarean section

AIM

To evaluate the effect of elective induction at term for women with gestational diabetes mellitus (GDM) on the risk for cesarean delivery.

STUDY DESIGN

This is a retrospective case-control matched study, based on a single-center computerized database, 2005-2011. The medical records were reviewed for GDM management and glycemic control. For the study, two groups were defined: Group 1, women diagnosed with GDM with an estimated fetal weight <4,000 g, electively induced at term; Group 2, women induced due to Term-PROM, an indication for term induction in normoglycemic women with uncomplicated pregnancies, matched for age and parity (ratio 1:2). The primary outcome was cesarean delivery and secondary outcomes included other maternal and neonatal events. Descriptive analyses and multivariate analyses models were fitted.

RESULTS

GDM was diagnosed in 1,873 (2.6 %) women of 72,374 births; 227 (12.1 %) were eligible for inclusion in Group 1 and matched with 454 women in Group 2. GDM management included diet in 103 (45.4 %), insulin in 81 (35.7 %), and oral hypoglycemic agents in 43 (18.9 %).The cesarean delivery rate was significantly higher in Group 1, 17.1 vs. 11.2 % (p = 0.02). Three out of four births complicated by shoulder dystocia and BW <4,000 g, occurred in Group 1 (p = 0.076) and were associated with no glycemic control. Other obstetrical-related outcomes such as instrumental birth, severe perineal tears, early postpartum hemorrhage and peripartum transfusion were similar between groups.

CONCLUSION

Elective induction at term for women with GDM is associated with an increased risk for cesarean delivery as compared to other elective induction of labor.

The effect of maternal body mass index on perinatal outcomes in women with diabetes

OBJECTIVE

To determine the effect of increasing maternal obesity, including superobesity (body mass index [BMI] ≥ 50 kg/m2), on perinatal outcomes in women with diabetes.

STUDY DESIGN

Retrospective cohort study of birth records for all live-born nonanomalous singleton infants ≥ 37 weeks' gestation born to Missouri residents with diabetes from 2000 to 2006. Women with either pregestational or gestational diabetes were included.

RESULTS

There were 14,595 births to women with diabetes meeting study criteria, including 7,082 women with a BMI > 30 kg/m2 (48.5%). Compared with normal-weight women with diabetes, increasing BMI category, especially superobesity, was associated with a significantly increased risk for preeclampsia (adjusted relative risk [aRR] 3.6, 95% confidence interval [CI] 2.5, 5.2) and macrosomia (aRR 3.0, 95% CI 1.8, 5.40). The majority of nulliparous obese women with diabetes delivered via cesarean including 50.5% of obese, 61.4% of morbidly obese, and 69.8% of superobese women. The incidence of primary elective cesarean among nulliparous women with diabetes increased significantly with increasing maternal BMI with over 33% of morbidly obese and 39% of superobese women with diabetes delivering electively by cesarean.

CONCLUSION

Increasing maternal obesity in women with diabetes is significantly associated with higher risks of perinatal complications, especially cesarean delivery.

"GINEXMAL RCT: Induction of labour versus expectant management in gestational diabetes pregnancies"

BACKGROUND

Gestational diabetes (GDM) is one of the most common complications of pregnancies affecting around 7% of women. This clinical condition is associated with an increased risk of developing fetal macrosomia and is related to a higher incidence of caesarean section in comparison to the general population. Strong evidence indicating the best management between induction of labour at term and expectant monitoring are missing.

METHODS/DESIGN

Pregnant women with singleton pregnancy in vertex presentation previously diagnosed with gestational diabetes will be asked to participate in a multicenter open-label randomized controlled trial between 38+0 and 39+0 gestational weeks. Women will be recruited in the third trimester in the outpatient clinic or in the Day Assessment Unit according to local protocols. Women who opt to take part will be randomized according to induction of labour or expectant management for spontaneous delivery. Patients allocated to the induction group will be admitted to the obstetric ward and offered induction of labour via use of prostaglandins, Foley catheter or oxytocin (depending on clinical conditions). Women assigned to the expectant arm will be sent to their domicile where they will be followed up until delivery, through maternal and fetal wellbeing monitoring twice weekly. The primary study outcome is the Caesarean section (C-section) rate, whilst secondary measurements are maternal and neonatal outcomes. A total sample of 1760 women (880 each arm) will be recruited to identify a relative difference between the two arms equal to 20% in favour of induction, with concerns to C-section rate. Data will be collected until mothers and newborns discharge from the hospital. Analysis of the outcome measures will be carried out by intention to treat.

DISCUSSION

The present trial will provide evidence as to whether or not, in women affected by gestational diabetes, induction of labour between 38+0 and 39+0 weeks is an effective management to ameliorate maternal and neonatal outcomes. The primary objective is to determine whether caesarean section rate could be reduced among women undergoing induction of labour, in comparison to patients allocated to expectant monitoring. The secondary objective consists of the assessment and comparison of maternal and neonatal outcomes in the two study arms. .

White's classification of maternal diabetes and vaginal birth after cesarean delivery success in women undergoing a trial of labor

OBJECTIVE

To estimate the rate of vaginal birth after cesarean delivery (VBAC) success in diabetic women based on White's Classification.

METHODS

This is a secondary analysis of an observational study conducted at 19 medical centers of women attempting VBAC. Diabetic women with singleton gestations, one prior cesarean delivery, and cephalic presentation who underwent a trial of labor were included. Vaginal birth after cesarean delivery success rates and maternal and neonatal complications were compared based on White's Classification.

RESULTS

Of 11,856 women who underwent trial of labor, 624 met all study criteria (class A1, 356; A2, 169; B, 70; C, 21; D/R/F, 8). Vaginal birth after cesarean delivery success in each group was: A1, 68.5% (95% confidence interval [CI] 63.4-73.3%); A2, 55% (95% CI 47.2-62.7%); B, 70% (95% CI 57.9-80.4%); C, 47.6% (95% CI 25.7-70.2%); and D/F/R, 12.5% (95% CI 0.3-52.7%). Maternal and neonatal complications were rare and not found to be different among groups.

CONCLUSION

Our study provides estimates for VBAC success based on White's classification and indicates a relatively low rate of perinatal complications after VBAC attempt for diabetic women.

LEVEL OF EVIDENCE

III.

"Early rupture of membranes" after the spontaneous onset of labor as a risk factor for cesarean delivery

OBJECTIVE

The objective of this study was to examine if patients with "early rupture of membranes (ROM)" after spontaneous onset of labor are at increased risk of cesarean section.

STUDY DESIGN

The rate of cesarean section was examined in 447 term singleton nulliparas who were admitted after the spontaneous onset of labor. The cases were divided into 2 groups: (1) "early ROM", defined as ROM at a cervical dilatation <4 cm (n=109); and (2) "late ROM", ROM at a cervical dilatation >or=4 cm (n=338).

RESULTS

(1) "Early ROM" occurred in 24.4% of the cases and the overall cesarean section rate was 5.6%; (2) there were no significant differences in the clinical characteristics including prepregnancy BMI, proportion of complicated pregnancies, total duration of labor, proportion of regional anesthesia, gestational age at delivery, and birthweight between the two groups of cases. However gravidas with "early ROM" were of advanced maternal age and had less cervical dilation on admission, shorter duration of 1st stage of labor, and more frequent use of oxytocin augmentation; (3) patients with "early ROM" had a threefold higher rate (11.9% vs. 3.6%) of cesarean section and a fourfold higher rate (11.9% vs. 3.0%) of cesarean section due to failure of progress than did those with "late ROM" (p<0.005 for each); (3) 92% (23/25) of cesarean sections were performed due to failure to progress; and (4) there was no significant difference in the rate of histologic chorioamnionitis between the two groups of cases.

CONCLUSION

"Early ROM" after the spontaneous onset of labor is a risk factor for cesarean section in term singleton nulliparas.

Surveillance of cesarean section deliveries, New Jersey, 1999-2004

BACKGROUND

Nationally and in New Jersey, the cesarean delivery rate has been increasing steadily for nearly a decade, and especially since 1999. The purpose of this study was to describe recent trends in cesarean section delivery in New Jersey.

METHODS

Data on delivery method, medical indications and patient characteristics were extracted from electronic birth certificate files.

RESULTS

Cesarean section deliveries increased as a proportion of live births by 6 percent annually. Growth was roughly uniform across Robson's clinical classification. Repeat cesareans contributed only proportionately to the overall trend. The greatest acceleration was observed for procedures without trial of labor, and in medical situations where cesarean delivery had been relatively rare.

CONCLUSIONS

Medical indications recorded on the birth certificate explained little of the rapid growth in utilization of cesarean delivery, since trends were comparable in most categories we examined. A sustained autonomous shift in practice patterns, patient preferences, or both seems the most likely driver of the overall trend.

Secular trends in cesarean delivery rates among macrosomic deliveries in the United States, 1989 to 2002

OBJECTIVES

We describe national trends in cesarean delivery rates among macrosomic infants during 1989 to 2000 and evaluate the maternal characteristics and risk factors for macrosomic infants delivered by cesarean section as compared to macrosomic infants delivered vaginally.

STUDY DESIGN

We analyzed US 1989 to 2000 Natality files, selecting term (37 to 44 week) single live births to U.S. resident mothers. We compare macrosomic infants (4000 to 4499, 4500 to 4999 and 5000+ g infants) to a normosomic (3000 to 3999 g) control group.

RESULTS

The proportion of cesarean deliveries among 5000+ g infants increased significantly over the time period. The adjusted odds ratio of cesarean delivery increased for all macrosomic categories over the 12-year period, as compared to normal birth weight infants.

CONCLUSIONS

Rates of cesarean delivery among macrosomic infants continue to increase despite a lack of evidence of the benefits of cesarean delivery within this population. Further exploration of the rationale for this trend is warranted and should include the development of an optimal delivery strategy for such patients.

Diet-controlled gestational diabetes mellitus does not influence the success rates for vaginal birth after cesarean delivery

OBJECTIVE

We sought to determine whether women with diet-controlled gestational diabetes mellitus who attempt vaginal birth after cesarean delivery are at increased risk of failure, when compared with their non-diabetic counterparts.

STUDY DESIGN

We identified 13,396 women who attempted vaginal birth after cesarean delivery among 25,079 pregnant women with a previous cesarean delivery who were delivered between 1995 and 1999 at 16 community and university hospitals. Analysis was limited to 9437 women without diabetes mellitus and 423 women with diet-controlled diabetes mellitus who attempted vaginal birth after cesarean delivery with a singleton gestation and 1 previous low-flap cesarean delivery. Data that were collected by trained abstractors, included demographics, medical history, and both pregnancy and neonatal outcomes. Multivariable logistic regression analysis was performed to determine an adjusted odds ratio for vaginal birth after cesarean delivery success among women with diet-controlled gestational diabetes compared with women with no diabetes mellitus. We controlled for birth weight, maternal age, race, tobacco, chronic hypertension, hospital settings, labor management, and obstetric history.

RESULTS

Forty-nine percent of the women with gestational diabetes mellitus and 67% of the women with no diabetes mellitus attempted vaginal birth after cesarean delivery. The success rate for attempted vaginal birth after cesarean delivery among gestational diabetic women was 70%, compared with 74% for non-diabetic women. We found that gestational diabetes mellitus is not an independent risk factor for vaginal birth after cesarean delivery failure. The relative risk for vaginal birth after cesarean delivery success in women with gestational diabetes mellitus compared with women without gestational diabetes mellitus was 0.94 (95% CI, 0.87-1.00). After an adjustment was made for confounding, the odds ratio for success with gestational diabetes mellitus was 0.87 (95% CI, 0.68-1.10).

CONCLUSION

Women with diet-controlled gestational diabetes mellitus who were carrying singleton fetuses who had no more than 1 previous low flap cesarean delivery should be counseled that their disease does not decrease their chances for a successful vaginal birth after cesarean delivery. Among diet-controlled diabetic women, the overall success rate for vaginal birth after cesarean delivery remains acceptable, and attempted vaginal birth after cesarean delivery should not be discouraged solely on the basis of gestational diabetes mellitus.

Induction of labor versus conservative management of pregnant diabetic women

Reasons for inducing labor at term in pregnancies complicated by diabetes include the avoidance of fetal demise and the prevention of excessive fetal growth and its concomitant conditions, shoulder dystocia and Cesarean delivery. Objectively evaluating the risks and benefits of labor induction is potentially confounded by the status of the cervix at the time of initiation of induction, early determination of an arrest disorder and physician bias toward Cesarean delivery for women who have diabetes. In non-diabetic women, incorporating estimates of fetal weight in deciding the route of delivery has not diminished the incidence of shoulder dystocia, and may have increased the incidence of Cesarean deliveries. Currently available evidence suggests that, while induction of labor for women who have diabetes may not carry much maternal or fetal risk, the benefit of this procedure is unclear.

A uniform regimen enables decentralized care of diabetic pregnancies

AIMS

A nationwide recommendation to standardize the care of diabetic pregnancies in different hospitals was given in Finland in 1993. The Medical Birth Register (MBR) was used to investigate whether these recommendations have been accepted and how they have affected the outcome of newborns.

METHODS

Data on 1442 singleton pregnancies complicated by insulin-treated diabetes in 1991-1995 were obtained from the MBR.

RESULTS

The incidence of insulin treatment during pregnancy was 4.5 per 1000 births. Sixty-six per cent (n = 954) of all women had Type 1 diabetes. During the study period, the number of deliveries managed in tertiary centres decreased from 59% to 47% (95% confidence interval [CI] 39-58%) and care was more often carried out on an out-patient basis. The perinatal mortality rate (>or= 28 weeks of gestation) declined from 19.3 to 8.2/1000, being 12.6/1000 in the whole diabetic population and 5.5/1000 in the general population (95% CI 3.4-8.8/1000). The risk was especially increased in insulin-treated gestational diabetic (GDM) pregnancies (14.3/1000). The proportion of macrosomic newborns (31.7%) in diabetic women was significantly higher than among the general population (3.2%) (95% CI 27.0-33.9%).

CONCLUSIONS

The decentralization and change-over to a mainly out-patient basis of management does not appear to have increased the number of cases of adverse outcome of diabetic pregnancy when patients have been selected to the appropriate level of care. The risks in insulin-treated GDM pregnancies were almost similar to Type 1 diabetes. To succeed, there must be a standardized care programme, continuous education and motivated personnel.