Gestiational DM

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Gestational diabetes mellitus: A risk factor fornon-elective cesarean sectionjog_1659 154..159

Rosrio Gorgal1, Elisabete Gonalves1, Mnica Barros1, Gabriela Namora1,ngela Magalhes2, Teresa Rodrigues3 and Nuno Montenegro1

Departments of 1Gynecology and Obstetrics, 2Endocrinology and 3Epidemiology, So Joo Hospital, Faculty of Medicine,University of Porto, Porto, Portugal

Abstract

Aim: To assess whether gestational diabetes mellitus (GDM) is associated with non-elective cesarean section.Material and Methods: A retrospective cohort study was conducted at the Department of Obstetrics of a levelIII hospital. Between January 2004 and November 2007, women admitted in labor or with spontaneous rupture

of membranes, at term, and with a singleton cephalic presenting fetus were eligible. From these, 220 womenwith GDM and 660 glucose-tolerant women, delivered immediately after, were selected. The associationbetween GDM and non-elective cesarean was estimated using modified Poisson regression analysis. Relativerisks were adjusted for age, pre-pregnancy body mass index, gestational weight gain, previous cesarean,gestational age at delivery and birthweight.Results: Non-elective cesarean section rate for women with GDM was 19.5% compared to 13.5% for non-diabetic women. The crude relative risk of cesarean section was 1.45 (95% CI 1.042.02) for women with GDM.After adjustment for confounders, the association between GDM and non-elective cesarean section remainedpositive and statistically significant (RR = 1.52; 95% CI 1.062.16). No significant differences in cesareanindications were found between the two groups.Conclusion: GDM was disclosed as a risk factor for non-elective cesarean section. Knowledge of the conditionmay have influenced obstetrical practice, favoring cesarean delivery.

Key words: fetal macrosomia, gestational diabetes mellitus, labor and delivery, non-elective cesarean section,reproductive endocrinology.

Introduction

Gestational diabetes mellitus (GDM) refers to anydegree of glucose intolerance with onset or first recog-nition during pregnancy.1 It occurs in 29% of all preg-nancies and accounts for 90% of cases of diabetesmellitus complicating pregnancy.2

Women with GDM are at increased risk for adverseperinatal outcomes such as macrosomia, birth traumaand neonatal metabolic abnormalities, mainly whenmetabolic control is suboptimal.

The degree to which GDM is related to anincreased rate of cesarean section is less certain.Higher rates of cesarean section may result frommacrosomia associated with fetal insulin response toincreased maternal glucose levels during pregn-ancy or changes in the obstetrical management due tothe knowledge that the mother has GDM.3,4 The lack

of uniform international standards for the ascertain-ment and diagnosis of GDM and factors such asobesity, advanced maternal age and other medicalcomplications, rather than the glucose intolerance

Received: September 19 2010.Accepted: March 29 2011.Reprint request to: Dr Rosrio Gorgal, Department of Gynecology and Obstetrics, Hospital de S. Joo, Faculdade de Medicina daUniversidade do Porto, 4200-319 Porto, Portugal. Email: [email protected]

doi:10.1111/j.1447-0756.2011.01659.x J. Obstet. Gynaecol. Res. Vol. 38, No. 1: 154159, January 2012

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level, per se, may further confound the associationbetween GDM and cesarean section.

The objective of this study was to assess whetherGDM is a risk factor for non-elective cesarean section.

Material and MethodsA retrospective cohort study was conducted at theDepartment of Gynecology and Obstetrics of Hospitalde So Joo, a Portuguese level III hospital. A comput-erized database of all admissions to the Maternal-FetalMedicine Unit, between January 2004 and November2007, was used. Demographic, antenatal and intrapar-tum data were collected for all 8320 live singleton termbirths.

The analysis was restricted to women admitted inlabor or with spontaneous premature rupture ofmembranes (SPROM), at term, regardless of the sub-

sequent need for augmentation or induction of labor.According to institutional guidelines for the manage-ment of SPROM at term, labor should be inducedwith oxytocin when Bishop score (BS) is 5 or greater,or dinoprostone used for cervical ripening, when BSis less than 5.

Elective cesarean section and non-cephalic presenta-tion were exclusion criteria. Non-elective cesareansection was defined as the surgical delivery of an infantat any time during labor or after SPROM. The indica-tions for cesarean section were grouped in two maincategories: fetal distress and failure to progress.

Criteria used to define failure to progress were (1)prolonged latent phase (>20 h in nullipara and >14 h inmultipara); (2) arrest of dilatation for more than 4 hunder oxytocic perfusion; and (3) arrest of descent formore than 2 h in nullipara or more than 1 h in multi-para (intervals extended 1 h with use of locoregionalanesthesia).

Fetal distress was diagnosed when at least one of thefollowing was present in fetal heart rate (FHR) tracings:(1) decreased long variability for more than 50 min; (2)decreased short variability for more than 30 min; (3)prolonged deceleration with decreased variability formore than 5 min or with normal variability for more

than 8 min; (4) repetitive decelerations with decreasedvariability for more than 10 min; and (5) non-reassuring FHR tracings with ST events in fetal electro-cardiographic ST segment analysis.

Macrosomia was defined as birthweight greater than4000 g.

The prevalence of GDM among the 8320 singletonterm pregnancies was 5.1% (n = 425). Two-hundred

and twenty women with GDM fulfilled the criteria forinclusion (51.8%) and the remaining were excludedbecause of labor induction (n = 137; 32.2%) or electivecesarean section (n = 68; 16.0%). For each womanwith GDM, three glucose-tolerant women deliveredimmediately after were selected (n = 660).

The cesarean section rate of the sample of womenwith GDM was compared to that of the glucose-tolerant group.

Approximately 60% of women with GDM and 26%of glucose-tolerant women attended antenatal care atour Outpatient Clinic.

Among us, the screening for GDM is offered to allpregnant women, between 24 and 28 weeks of gesta-tion, using a 50-g 1-h glucose challenge test. Earlierscreening in the first trimester of pregnancy is per-formed in those women at higher risk for GDM (ageolder than 35 years, obesity, family history of diabetes,

previous GDM, previous macrosomic infant or previ-ous unexplained fetal demise). If the result of theglucose challenge test is abnormal (7.8 mmol/L[140 mg/dL]), the patient undergoes a 100-g 3-h oralglucose tolerance test. The Carpenter-Coustan criteria(two or more abnormal plasma glucose values) areused for the diagnosis.5 A fasting glucose level greaterthan 7 mmol/L (126 mg/dL) or a casual plasmaglucose greater than 11.1 mmol/L (200 mg/dL) withsymptoms of hyperglycemia meet the threshold for thediagnosis of diabetes without the need for a glucosechallenge test.

Treatment included recommendations for physicalactivity and dietary counseling in 81.8% of womenwith GDM (n = 180). Insulin was prescribed because ofinsufficient glycemic control in 12.7% of cases (n = 28)and almost all of these attended antenatal care at ourObstetric and Endocrinologic Outpatient Clinic (89.3%;n = 25). In our institution, target glycemic values usedfor diabetic women are lower than 5 mmol/L (90 mg/dL) in the fasting state and before meals and lower than6.7 mmol/L (120 mg/dL) 2 h after meals. Informationregarding treatment was unavailable in 5.5% of cases(n = 12).

In our Hospital, termination of pregnancy is rou-

tinely offered to women with GDM at 40 weeks of ges-tation or 12 weeks earlier if fetal macrosomia issuspected or in the presence of inadequate maternalglycemic control. Among glucose-tolerant women,pregnancy is allowed to continue till 41 weeks if thereis no complication.

Baseline maternal characteristics, gestational age atdelivery and birthweight were compared between

Gestational diabetes and cesarean section

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Discussion

Few studies have specifically addressed factors relatedto cesarean section among women with GDM. Con-flicting results regarding the association between GDMand cesarean section can be found in the literature.

Goldman et al.4 reported an overall cesarean sectionrate of 35.3% for women with GDM compared to 22.0%for glucose-tolerant women. Among women in labor,

cesarean rate was 21.8% in GDM compared with 15.6%in glucose-tolerant subjects, but the difference was notstatistically significant. Within the ideal-weight sub-group of women in labor, significantly more womenwith GDM were delivered by cesarean section (24.4%vs 14.0%). Given the similar rates of abnormalities inlabor, birth trauma and fetal macrosomia betweengroups, it was stated that the increased rate of cesareansection was probably related to patterns of physiciandecision-making. Naylor et al.3 from the Tri-TorontoHospitalGestational Diabetes Project reported cesareansection rates of 20% for glucose-tolerant women, 29.6%for untreated women with GDM and 33.6% for treated

women with GDM. After adjustment for potential con-founders, there was a persistent and significant associa-tion between treated GDM and cesarean delivery (OR1.6; 95% CI 1.02.5) and the authors stated that, eventhough treatment of GDM normalizes birthweight,cesarean section rates remain high among women withGDM, probably because recognition of GDM may leadto a lower threshold for surgical delivery that mitigates

the potential benefits of treatment.Also, Jacobson et al.6

reported a higher cesarean section rate in patients withGDM compared with non-diabetic women (29.9% vs18.9%) that was explained by an increased rate of repeatcesarean section in the former group (16.5% vs 6.0%).More recently, the Hyperglycemia and Adverse Preg-nancy Outcome (HAPO) Study7 aimed to clarify risks ofadverse outcomes associated with degrees of maternalglucose intolerance less severe than overt diabetesmellitus. For primary cesarean section, odds ratio foran increase in the glucose level by 1-SD were 1.11 (95%CI, 1.061.15) fasting, 1.10 (1.061.15) 1-h and 1.08(1.031.12) 2-h plasma glucose level. In this study of23 316 pregnant women, women and caregivers wereunaware of the glucose values.

Different findings were also reported. Moses et al.8

found a slightly increased rate of cesarean sectionamong women with GDM (19.8% vs 15.6%), but the

difference was not significant after controlling for ageand parity. Langer et al.9 demonstrated that an intensi-fied management approach to GDM resulted in areduction in cesarean section rates to levels lower thanthe conventional management group (overall cesareansection rates of 15.0% and 21.5%, and primary sectionrates of 13.0% and 19.0%, respectively) and comparableto the non-diabetic women (overall section rates of13.7% and primary section rates of 11.0%). Hod et al.10

in a population-based longitudinal study reported thata more strict control of diabetes and an active manage-ment protocol for early elective delivery throughout

time were responsible for a significant reduction inmacrosomia coupled with a non-significant decrease incesarean deliveries among women with GDM. Duringthe last period of this study, no significant differenceswere found regarding the overall and primary cesar-ean section rates between GDM and control women(16.2% and 13.6% vs 15.5% and 11.8%, respectively).

The results of the present study show that GDM is arisk factor for non-elective cesarean section inde-pendently from maternal age, pre-pregnancy BMI,gestational weight gain, previous cesarean section, ges-tational age at delivery and birthweight. In fact, womenwith GDM presented a 52% increase in the risk of

non-elective cesarean delivery. Given the similarrates of fetal distress and failure to progress in bothgroups, these results corroborate the hypothesis thatknowledge that a woman has GDM may modify theobstetrical practice and increase the risk of cesareansection in this pregnant patient population.

Macrosomia is a major adverse outcome when evalu-ating GDM because it often leads to labor dystocia and

Table 2 Indications for non-elective cesarean section ingestational diabetes mellitus (GDM) and glucose-tolerant women

GDM(n = 43)

Glucose-tolerant(n = 89)

P-value

Failure to progress,n (%)

30 (69.8) 61 (68.5) 0.886

Fetal distress, n (%) 13 (30.2) 28 (31.5)

Table 3 Modes of vaginal delivery in gestational diabetesmellitus (GDM) and glucose-tolerant women

GDM(n = 177)

Glucose-tolerant(n = 571)

P-value

Eutocic delivery, n (%) 126 (71.2) 413 (72.3) 0.767Instrumental delivery,

n (%)51 (28.8) 158 (27.7)




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increases the risk of cesarean delivery. In this study, therate of macrosomia in pregnancies with diagnosedGDM was not significantly different from that in theglucose-tolerant group (5.9% vs 4.8%; P = 0.536). It maybe that pregnancies with macrosomia detected antena-tally were electively terminated before labor or SPROMand, hence, excluded from the study. This furtherstrengthens the hypothesis that caregivers managedGDM patients differently, changed their obstetricalpractice and were more prone to interpret the clinicalsituation as requiring cesarean delivery.

Previous cesarean section reduces the chance ofhaving a subsequent vaginal birth. In this study, theproportion of women with GDM and a previous cesar-ean delivery did not differ significantly from that ofglucose-tolerant women (10.0% vs 8.8%; P = 0.588).Also, after restricting the analysis to women with noprevious cesarean section, a significantly increased risk

of non-elective cesarean delivery in women with GDMpersisted.

It is generally acknowledged that induction of laborfor medical indications is associated with an increasedrisk of cesarean delivery. In our study, we eliminatedcases of induction of labor and those of elective cesar-ean section, either primary or repeated, and comparedonly GDM and glucose-tolerant women in labor orwith spontaneous premature rupture of membranes. Ifthis selection had not been made it would be expect-able to obtain an even higher rate of cesarean section inwomen with GDM.

Differently from most studies that evaluated a seriesof other maternal and perinatal outcomes, we restrictedour analysis to the mode of delivery in women withGDM. Adjusted cesarean section rates were previouslyreported only by Moses et al.8 and Naylor et al.3 In theformer, the association was adjusted only to a limitednumber of variables while the latter included similarconfounding factors in the multivariate analysis thatwe did.

Our study had some limitations. The database hadno insight into the degree of glycemic control in dia-betic patients or the gestational age of diagnosis ofGDM. It would have been very useful to evaluate cesar-

ean section rates in diabetic women with good andinadequate glycemic control and compare them withthose in glucose-tolerant pregnant women. Despitethis, similar rates of macrosomia were observed in bothgroups, which may suggest that a reasonable level ofglycemic control was achieved among women withGDM included in this study. Also, we lacked informa-tion on previous macrosomia.

Several women with diabetes diagnosed duringpregnancy may have pre-existing type 2 diabetes.5

Even though we did not evaluate the rate of persistingdiabetes postpartum, women with GDM were found tobe older and more obese at the beginning of pregnancythan their glucose-tolerant counterparts, which mayindicate that some cases of GDM included in the studymay, possibly, represent cases of undiagnosed type 2diabetes mellitus.

In conclusion, this study supports an increment inmaternal morbidity for women with GDM, expressedas an increased rate of non-elective cesarean delivery.These results, however, may be somewhat difficult toexplain with the set of data presented here. Besides,although cesarean section has evolved as part of crite-ria to evaluate disease, it should not be the end point inGDM because this procedure is not only related todisease morbidity but also to physician decision-

making and performance. If this is the case and weassume that cesarean deliveries in women with treatedGDM are more related to expectations of caregiversthan to clinical indications, one can clearly question thepotential advantages of diagnosing GDM, which willbe clearly offset by the cost, inconvenience and compli-cations of a higher cesarean section rate. Further assess-ment of the mode of delivery is therefore needed todetermine the optimal obstetrical care in this patientpopulation.

References

1. Hillier TA, Vesco KK, Pedula KL, Beil TL, Whitlock EP,Pettitt DJ. Screening for gestational diabetes mellitus: A sys-tematic reviewfor theU.S. preventive services task force.AnnIntern Med 2008; 148: 766775.

2. Jovanovic L, Pettitt DJ. Gestational diabetes mellitus. JAMA2001; 286: 25162518.

3. Naylor CD, Sermer M, Chen E, Sykora K. Cesarean deliveryin relation to birthweight and gestational glucose tolerance:Pathophysiology or practice style? JAMA 1996; 275: 11651170.

4. Goldman M, Kitzmiller JL, Abrams B, Cowan RM, Laros RK.Obstetric complications with GDM. Diabetes 1991; 40 (Suppl2): 7982.

5. Metzger BE, Coustan DR. Summary and recommendations of

the fourth international workshop-conference on gestationaldiabetes mellitus. Diabetes Care 1998; 21 (Suppl 2): B161B167.

6. Jacobson JD, Cousins L. A population-based study of mater-nal and perinatal outcome in patients with gestational diabe-tes. Am J Obstet Gynecol 1989; 161: 981986.

7. The HAPO Study Cooperative Research Group, Metzger BE,Lowe LP, Dyer AR et al. Hyperglycemia and adversepregnancy outcomes. N Engl J Med 2008; 358: 19912002.

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8. Moses RG, Knights SJ, Elizabeth ML et al. Gestational diabe-tes: Is a higher cesarean section rate inevitable? Diabetes Care2000; 23: 1518.

9. Langer O, Rodriguez DA, Xenakis EMJ, McFarland MB,Berkus MD, Arredondo F. Intensified versus conventional

management of gestational diabetes. Am J Obstet Gynecol1994; 170: 10361047.

10. Hod M, Bar J, Peled Y et al. Antepartum management proto-col: Timing and mode of delivery in gestational diabetes.Diabetes Care 1998; 21 (Suppl 2): B113B117.



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