Gestational diabetes: is a higher cesarean section rate inevitable?

Abstract

15 Gestational diabetes mellitus (GDM) is any degree of glucose intolerance with onset or first recognition during p regnancy (1). Women with undiagnosed or poorly managed GDM are at incre a s e d risk of having a large for gestational age (LGA) infant. A LGA infant may be re s p o nsible for cephalo-pelvic dispro p o rtion and hence an increased risk of obstetric intervention including cesarean section.While it is not invariable that women with GDM will have a higher section rate (2,3), it has been suggested recently that knowledge by the obstetric care pro v i d e r s that a woman has GDM is likely to lead to a higher rate (4-6). If this is the case, then some of the potential advantages of diagnosing GDM may be offset by the cost, inconvenience, and complications of this higher section rate. However, if higher section rates are found only in some hospitals, then knowledge about this local practice should not be endorsed as a general disincentive to test women for GDM.The aim of this study was to determ i n e the cesarean section rate in a consecutive series of women with GDM and to compare the reasons for section with a control gro u p of consecutive glucose-tolerant women. RESEARCH DESIGN AND M E T H O D S -The diagnosis of GDM was based on the recommendations of the Australasian Diabetes in Pregnancy Society (ADIPS) criteria (7). Unless indicated earlier in pre g n a n c y, all women were tested at the beginning of the 3rd trimester with a 75-g oral glucose tolerance test (GTT) administ e red in the morning after an overnight fast. Although the ADIPS criteria allow the option of a pre l i m i n a ry screening test, all women in our Health Area of New South Wales, Australia have the definitive GTT as a one-stage test. Women were diagnosed with GDM if the 2-h plasma glucose level was 8.0 mmol/l (144 mg/dl). Although the ADIPS criteria specify that GDM is also diagnosed if the fasting level is 5.5 mmol/l (99 mg/dl), 92% or more of cases of GDM a re diagnosed on the result of the 2-h level (8). For local logistical reasons some women only have the 2-h test on the GTT (9).The women with GDM who had had a section were from a consecutive series of women re f e rred for the medical management of their GDM to a diabetologist (R.G.M.) over the period 1990-1998. All details were obtained from a compre h e n s i v e clinical database established and maintained for all women treated. All women were seen initially and reviewed as re q u i red by a dietitian and diabetes educator. All women received a carbohydrate-controlled diet and p e rf o rmed home glucose monitoring. The use of insulin was recommended if the fasting glucose was 5.5 mmol/l or the postprandial glucose levels were 8.0 mmol/l 1 h after a meal or 7.0 mmol/l 2 h after a meal. Obstetric care was conducted independently of the medical management and t h e re were no combined appointments. The number of obstetric care providers primarily responsible for the deliveries varied over the period when the data was being collected but was approximately six.For compa...

The prevalence of hyperglycaemia in pregnancy in Australia

“…[23][24][25] However, in Australia, this in the past has not been inevitable. 26 Two major treatment interventions for women with GDM where the obstetric care provider was blinded to the glucose results showed no change 27 or a reduction 28 in the rate of sections. If in Australia overall, with an increase in the prevalence of HIP, the percentage of women having sections, with the subsequent neonatal interventions and increased length of hospital stay, were to remain unchanged or to increase, then much of the potential health and economic advantages would not be apparent.…”

Screening for gestational diabetes: a systematic review and economic evaluation

“…A New South Wales study reported a Caesarean section rate of 20% in women with GDM, compared to 16% in non-diabetic women, and the difference was partly explained by age and parity. 87 A Cochrane review also found that reduction in macrosomia is not necessarily followed by significant differences in the rates of sections, forceps deliveries or birth trauma. 65 Santini and Ales 88 have calculated that to prevent one case of macrosomia, 3716 women would have to be screened; 250 would require further tests such as ultrasound, and 134 more women would have Caesarean sections.…”

Screening for hyperglycaemia in pregnancy: a rapid update for the National Screening Committee

“…However, the increase in section rates as reported in Canada 9 was not seen in New South Wales. 14 The harms of intervention also need to be considered, including insulin treatment and hypoglycaemia. 7 Santini and Ales (1990) 15 calculated that to prevent one case of macrosomia, 3716 women would need to be screened, and 134 more women would have caesarean sections.…”