Can Macrosomia Be Prevented?

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Summary

Objective: To determine whether strict glycemic control during diabetic pregnancy combined with elective early induction of labor reduces the rate of macrosomia, birth trauma, and it’s influences on the C/S rate. Materials and Methods: Data were collected on the outcome of gestational diabetes (GDM) from 1/1980 to 12/1998. We investigated the relationship between mode of delivery, macrosomia (>4000 g), perinatal morbidity and mortality to maternal glycemic control and departmental delivery protocols. Results: Compared with results before implementation of our management policy there was a statistically significant decline in the incidence of macrosomia (17.9% to 4.5% P<0.05). Induction of labor increased from 15% to 35% of the pregnancies, but the rate of C/S remained unchanged (20.6%, and 17.8%, respectively). Conclusion: Maintaining strict glycemic control and adhering to early elective delivery have a significant effect on reducing the rate of macrosomia, without affecting the rate of cesarean deliveries.


Introduction

In patients with gestational diabetes(GDM) accelerated fetal growth remains a major perinatal complication. Macrosomia is permanent and has been associated with an increased risk of birth trauma and cesarean delivery rate. Due to the tendency of accelerated fetal growth prolonging gestation in diabetic pregnancy leads to an increase in absolute infant size. Our objective was to investigate the effectiveness of strict metabolic control during pregnancy coupled with term (~38 wks) early induction of labor based on estimated fetal weight in reducing macrosomia, birth trauma and C/S rates. 

Materials and Methods

From 1 January 1980 to 31 December 1995 data were collected on the outcome of GDM and normal pregnancies admitted to the department of Obstetrics and Gynecology, Rabin Medical Center. Patients represented the entire spectrum of the Israeli population. Specifically, we sought to determine the relationship between perinatal macrosomia (>4000g), management of labor, mode of delivery, and perinatal morbidity and mortality to maternal glycemic control and departmental labor and delivery criteria.

The classification, diagnosis, treatment and follow-up of patients with GDM were performed according to the specific recommendations proposed by American Diabetes Association (1) and the American College of Obstetrics and Gynecology (2). During the study period 1980-1989, patients with fasting glucose levels of >5.8mmol/L or postprandial levels of >7.8 mmol/L were given insulin treatment. Between 1990 and 1992, patients were also instructed to aim maintain a plasma glucose level of 5.8 mmol/L. As of 1993 insulin was started at fasting levels of =5.3 mmol/L and/or 2-h postprandial levels of 6.6 mmol/l, and the glycemic goal was set at =5.3 mmol/L. In addition, as of 1993, labor was induced at 38 weeks in all patients with a suspected large for gestational age fetus (LGA- estimated fetal weight above the 90th percentile) by vaginal application of prostaglandin E2 pessaries (3 mg). Elective cesarean section was performed if the estimated fetal weight (EFW) was =4000 g.

Results

During the 18 years of the study 82,979 women gave birth in our department. Of these 2045 (2.46%) were diagnosed with GDM. Labor induction rate in the GDM patients was 35% compared with 10% in the non-GDM patients. The maintenance of strict metabolic control in the GDM patients combined with the early induction of labor protocol was accompanied by rates of macrosomia, LGA fetuses, shoulder dystocia, and cesarean births not significantly higher than those for the non-GDM subjects (as published in reference 3). Macrosomia rates declined gradually from 17.9% to 8.8% and 4.5% in 1985-1992, 1992-1995 and 1998, respectively. Overall C/S rates did not alter significantly, 20.6%, 16,2%, 17.8%, respectively). Shoulder dystocia rates declined but did not reach statistical significance (1.5%, 0.6%, in1985 compared with 1995). A similar trend was observed with perinatal morbidity and mortality. 

Conclusion

We hypothesized that in the management of pregnancies with GDM combining early detection and strict metabolic control with early induction of labor near term- to avoid excessive fetal growth in utero, could lead to more favorable perinatal outcome. To test this assumption, we studied pregnancy outcome in GDM patients compared with the non-GDM normal pregnant population over a period of 18 years in which none, some, or all of these criteria were applied. The results indicate a gradual and constant decline in several important feto-maternal complications (for comprehensive data, see reference 3). During the last follow up period (1993-1998), the target normoglycemic level was lowered to =5.3 mmol/L, strict metabolic control was implemented, and labor was induced at a lower mean gestational age according to the EFW. It is only after applying all three aspects of the management policy together that we succeeded to decrease the complications occurring in GDM patients to rates that compared favorably with those observed in the general non-GDM population.

The main perinatal complication of GDM is accelerated fetal growth. It increases the risk of birth trauma and the likelihood of performing a cesarean delivery. Randomized controlled studies have assessed the effects of primary dietary therapy in pregnancies with GDM (4) and very tight and intensified glycemic control in women with insulin dependent pregnancies (5). These studies were not able to prove clear evidence of benefit in perinatal outcome. Similarly, two randomized controlled trials from the Cochrane Pregnancy and Childbirth Group trials register (6) involving 313 women investigated the effects of a policy of early labor induction for suspected fetal macrosomia on method of delivery and maternal or perinatal morbidity. Compared to expectant management, induction of labor for suspected macrosomia did not reduce the risk of cesarean section or instrumental delivery. Perinatal morbidity was similar between groups.

Contrary to the conflicting results regarding management of fetal macrosomia, our study clearly demonstrates that although it might not be sufficient to pursue one of the two approaches, by combining the two management protocols and strictly implementing them together, the problem of macrosomia can be overcome, achieving rates similar to the healthy non-diabetic pregnant population. This has been attainable at low cost and minimal clinical recourses, without increasing the rate of cesarean or instrumental deliveries, but merely by adhering and strictly implementing tight glycemic control together with early induction of labor.

References:

References

1. National Diabetes Data Group: Classification and diagnosis for diabetes mellitus and other categories of glucose intolerance. Diabetes 28:1037-1059, 1979.

2. American college of obstetrics and Gynecologists; Management of diabetes mellitus in pregnancy. AGOG Tech Bull 92;1-5,1986.

3. HOD,M, et al,. Antepartum management protocol; timing and mode of delivery in gestational diabetes. Diabetes care 21(sup. 2):B113-117,1998.

4. Walkinshaw SA. Dietary regulation for ‘gestational diabetes’ (Cochrane Review). In: In: The Cochrane Library, issue 2,: Update Software, Oxford, 1999.

5. Walkinshaw SA. Very tight versus tight control for diabetes in pregnancy (Cochrane review). In: The Cochrane Library, issue 2,: Update Software, Oxford, 1999.

6. Irion O, Boulvain M. Induction of labor for suspected fetal macrosomia (Cochrane Review). In: The Cochrane Library, issue 2,: Update Software, Oxford, 1999.