Gestational diabetes: obstetric and neonatal outcome in 411 cases.

AIM: To study the obstetric and neonatal outcome of women with gestational diabetes mellitus. METHODS: Four hundred and eleven (411) women with gestational diabetes mellitus were studied retrospectively. The control group was 3,391 non-diabetic women delivered in the same period. RESULTS: Women with gestational diabetes mellitus had a significantly higher incidence of pregnancy-induced hypertension, and more were likely to present with malpresentation in labour. They had a higher incidence of surgical induction and an increased incidence of elective and emergency Caesarean section rate compared to controls. The neonatal outcome was excellent. The perinatal morbidity and mortality were similar to the non-diabetic controls. CONCLUSION: The excellent outcome of the women with gestational diabetes mellitus in this study is attributed to tight control of blood glucose level and close attention given to this group of patients.

Congenital abnormalities and pregestational diabetes mellitus in pregnancy.

Despite falling perinatal mortality rate, congenital malformation remains the major cause of mortality in infants of mothers with established diabetes. The perinatal mortality rate in this group of infants is 5 times the overall perinatal mortality rate in this hospital. It is well established that pre-pregnancy counselling and maintenance of euglycaemia during the periconception period are the keys to prevention of congenital malformation. We are able to offer pre-pregnancy counselling to 29% of our diabetic mothers who are diagnosed to have pregestational diabetes mellitus only after the 6 weeks postnatal oral glucose tolerance test. Even in the known established diabetes mellitus, 95% of the patients were first seen after the period of organogenesis (> 8 weeks). This could explain our high congenital malformation rate of 15.7%.

Obstetric outcome of pregestational diabetic pregnancies.

This retrospective study examined the obstetric and neonatal outcome in 23 pregestational diabetic pregnancies. The incidence of congenital malformations and mortality in infants of diabetic mothers was increased compared to the control population. Late booking for antenatal care and poor glycaemia control are probably the reasons for this high incidence. There was also a significantly higher preterm delivery and Caesarean section rate in the pregnancies complicated by pregestational diabetes. The neonatal morbidity was also higher than the controls in terms of jaundice, hypoglycaemia, respiratory distress syndrome and admissions to neonatal intensive care unit. Only with preconception counselling and tight glycaemia control in the periconception period and throughout pregnancy can we expect a drop in the complication rates in pregestational diabetic pregnancies.

Glycosylated haemoglobins in women with low risk for diabetes in pregnancy.

Glycosylated haemoglobin levels (HbA1) were determined in 489 normal pregnant Singaporean women, attending a diabetic screening programme using a 50g glucose challenge test. All subjects had no risk factors for diabetes mellitus nor a history of previous gestational diabetes. They were selected when the 1h 50g glucose challenge (GCT) is < 6.66 mmol/l or a 2h post-glucose level of < 7.77 mmol/l (a 75g OGTT is repeated within a week of an abnormal GCT). Another 18 subjects with normal OGTT but did not have a 50g glucose challenge done were also included in the study. Mean and normal range (2 SD) of HbA1 levels in all subjects were 4.64% and 3.66-5.62%, respectively. Mean HbA1 levels also varied with gestation and ethnic group. The HbA1 appeared to be low at early gestation with nadir at 21-24 weeks and thereafter returned to initial levels at term. In Chinese, mean HbA1 levels, random plasma glucose and 1h glucose challenge were significantly higher than those of the Malays but not the Indians. In referring to these levels, the variation within gestation and ethnic group must also be considered.

Glycosylated hemoglobins in pregnant women with normal and abnormal glucose tolerance.

Glycosylated hemoglobin (HbA1) levels were compared in low risk pregnant Singaporean women with normal and abnormal glucose response. HbA1 (mean +/- 1 SD) levels in normal and abnormal groups (489 and 72, respectively) were 4.65 +/- 0.49 and 4.85 +/- 0.50, respectively. While mean levels were significantly different, there was a considerable overlap of levels in both groups. At various gestation periods, mean HbA1 levels between normal and abnormal groups showed significant difference only at late gestation. The latter may have contributed to significant differences in HbA1 levels between normal and abnormal groups as a whole. The considerable overlap of HbA1 values in normal and abnormal groups indicate that HbA1 may be insensitive as a screening method for glucose intolerance.

The glucose challenge test: a screening test for gestational diabetes mellitus.

The 50g glucose challenge test (GCT) was evaluated as a method to screen for gestational diabetes in 540 low-risk pregnant women to establish its sensitivity and specificity, as well as to establish a relevant threshold plasma glucose value above which a diagnostic 75g oral glucose tolerance test (OGTT) would be indicated. If a threshold of 140 mg/dl is used, the diagnostic yield would be 28.5%. At a threshold of 130 mg/dl, the diagnostic yield fell to 25.4%; the sensitivity rose to 87.7% and the specificity declined to 67.1%. There was progressive increase in diagnostic sensitivity when the GCT was performed after 24 weeks without significant decrease in specificity. In low-risk populations, a 50g GCT should be performed between 24-28 weeks gestation.

Serial measurement of serum fructosamine and glycosylated haemoglobin as indices of glycaemic control in diabetic pregnancy.

Management of diabetic pregnancy requires objective information regarding blood glucose levels with the aim of achieving strict euglycaemia. Self-blood glucose monitoring and measurement of glycosylated haemoglobin (HbA1) are two methods widely adopted in clinical practice. Serum fructosamine assay was recently introduced as a parameter for assessing short-term glycaemic control. Our study compared serial measurement of serum fructosamine with HbA1 as indices of short-term glycaemic control in a group of diabetic pregnant women prospectively from early/mid-trimester till delivery. Patients performed self-blood glucose glucose concentration of the preceding two weeks were assessed. Our results showed that both serum fructosamine and HbA1 gave comparable information regarding short-term glycaemic control. Serum fructosamine estimation did not offer any distinct additional advantage as a retrospective index of diabetic control in the management of diabetic pregnancy.

No evidence of hearing loss due to fetal acoustic stimulation test.

The fetal acoustic stimulation test is used increasingly for fetal assessment. To evaluate the possibility of acoustic trauma, 465 children who had been exposed to vibroacoustic stimulation in utero were screened at 4 years of age for high-frequency hearing loss. A hand-held audiometer with test tones at 25 dB for 1000 and 4000 Hz was used because responses at this level indicate hearing within normal limits for middle and high frequencies. Thirty-one children failed the test. Failure to respond was followed by inspection of the ear canal for wax, tympanometry, and reflex measurement to assess the tympanic membrane, middle ear, and eustachian tube. Hearing was retested across the full frequency range using conventional audiometric technique, and referral for otolaryngologic examination and treatment was made if necessary. The causes of hearing loss were impacted wax in 12, current or recent upper respiratory tract infection with eustachian tube dysfunction and middle ear effusion in 15, and unresolved middle ear effusion after treatment with antibiotics for otitis media in two. Profound bilateral sensorineural hearing loss of unknown origin was found in one and slight bilateral gently sloping hearing loss in another. Retesting of all children with conductive hearing loss indicated that hearing had returned to normal after treatment. None of the children showed evidence of hearing loss.

The 75 and 50g OGTT response in normal pregnant women.

The 75 and 50g OGTT (Oral Glucose Tolerance Test) responses were studied in 86 normal healthy pregnant women (mean age 28.7 +/- 0.4 (SEM) years) at 28 and 32 weeks respectively. Of these were 50 Chinese, 20 Malays and 16 Indians. Mean glucose responses at fasting, 1 and 2h post glucose load were 78.3 +/- 0.7, 132.2 +/- 2.8 and 116.2 +/- 2.1 mg/dl respectively for the 75g OGTT and 78.5 +/- 0.7, 130.5 +/- 2.5 and 106.7 +/- 1.8 mg/dl respectively for the 50g OGTT. Except for the 2h responses, corresponding responses between both OGTTs were not significantly different. All races showed a similar OGTT response. Using a set criteria for diagnosis of abnormals resulted in gross inconsistency in the number of abnormals diagnosed for both OGTTs. However, the use of 95th percentile shows a closer agreement in the diagnosis of abnormal cases for both OGTTs. Also, the 2h OGTT response for the 75g OGTT is higher than that of WHO's criteria for impaired glucose tolerance. This emphasizes the need to establish our own reference range.

Lipid profiles during and after normal pregnancy.

Lipid profiles were estimated in two groups of normal healthy women comprising 39 non-pregnant women and 67 pregnant women at 28 and 32 weeks gestation and 6 weeks after delivery. Triglycerides, total, HDL and LDL cholesterols were high during pregnancy. Except for LDL cholesterols which remained constant, all the above decreased at 6/52 postnatally, but levels were still above those of normal non-pregnant women. Compared to the later, the atherogenic index, LDL/HDL cholesterol ratio was unchanged during pregnancy but significantly increased at 6/52 postnatally. These results may suggest that while total lipid levels increase during pregnancy, this is balanced by an even distribution of the lipoprotein fractions. After delivery, though lipid levels had decreased, the decrease in HDL cholesterol and increase in LDL cholesterol caused unfavourable changes in lipid-lipoprotein ratios. These changes may be due to the change in metabolism of the pregnant women as well as diet during and after pregnancy.

Home glucose monitoring in management of diabetes in pregnancy in Singapore.

The incidence for diabetes in pregnancy for 10,941 deliveries in the department over a 3 1/2 year period is 5.04% (551 patients). Of these, 33.2% (183 patients), were recruited for home glucose monitoring programme. The gestational diabetics form 76.3%, while pregestational diabetics form 23.7% of the patients. The total period of hospitalisation was less than 4 weeks in 89.4% of patients. The corrected (excluding those with birthweight of less than 1000 G) perinatal mortality rate was 5.78 per 1000.

Serum fructosamine concentrations in Singapore pregnant women.

Serum fructosamine levels in women at pregnancy (28 weeks' gestation) were determined. The women (n = 99) also participated in an oral glucose tolerance test (OGTT) with a 75g liquid glucose load, to determine their glucose tolerance. At 32 weeks' gestation, seventy-nine of them repeated the oral glucose tolerance test and fructosamine measurement. Results showed that fructosamine levels in pregnant women with normal glucose tolerance (2.20 +/- 0.19 mmol/l, n = 76), were not statistically different from those with glucose intolerance (gestational diabetes: 2.19 +/- 0.22 mmol/l, n = 23) at 28 weeks' and also 32 weeks' gestation. However, serum fructosamine levels in pregnant women were lower than those in non-pregnant subjects. Serum fructosamine measurement is not a sufficiently sensitive test for diagnosis of gestational diabetes.

Extremes of foetal birthweight for gestation in infants of diabetic mothers.

100 patients were registered at the Diabetic Clinic in 1981, where they were managed by a team of physician, obstetrician and paediatrician, based on a preset protocol. Only 92 patients were eventually analysed. The study showed a 1.3% incidence of pregnancies complicated by diabetes mellitus. The mean birthweights of infants of both gestational and established diabetics were heavier than that of the general population by race and gestation. 25% of the 92 infants of diabetic mothers have birthweight exceeding the 90th centile of population. Further division of the 92 patients into the "true gestational" diabetics, as shown by an oral glucose tolerance test performed 6 weeks post-natally, also showed a 25% incidence of macrosomia. Late antenatal booking, delayed detection of abnormal glucose tolerance and treatment attributed to the high incidence of macrosomia. Only one infant had birthweight below the tenth centile. There were no perinatal mortality in the 92 patients studied. Macrosomia is a common complication in infants of diabetic mothers despite a physician-obstetrician joint-care system. Also, the risk of having macrosomia amongst gestational diabetics is high.