Comparison of the 50 g capillary plasma glucose tolerance test with the 75 g venous plasma glucose tolerance test in pregnancy

OBJECTIVE

To compare the 50 g oral glucose tolerance test with capillary sampling used in the Mercy Hospital for Women, Melbourne with the 75 g test with venous sampling advocated by the Australasian Diabetes in Pregnancy Society.

METHODS

Both the 50 g and 75 g glucose tolerance tests were performed on 60 women. Criteria for diagnosing gestational diabetes were the combination of a 1-hour capillary plasma glucose > or = 9 mmol/l and a 2-hour glucose > or = 7 mmol/l for the 50 g test and a fasting glucose > or = 5.5 mmol/l and/or a 2-hour venous plasma glucose > or = 8.0 mmol/l for the 75 g test.

RESULTS

Twenty-eight of 60 women had gestational diabetes diagnosed with the 50 g test; 24 of these, and an additional 5 had gestational diabetes diagnosed on the 75 g test. Twenty-seven women had normal results on both tests. The kappa statistic was 0.70. The 1-hour glucose value was similar for both tests, but the 2-hour value was significantly higher for the 75 g test (mean difference 0.65 mmol/l, 95% confidence limits 0.24-1.01 mmol/l, p = 0.003). The area under the curve was similar for the 2 tests.

CONCLUSIONS

The 2 tests diagnose similar women as having gestational diabetes. The combination of a 75 g load and venous sampling gives similar 1-hour but higher 2-hour values than a 50 g load and capillary sampling.

Diabetes

There is now strengthening evidence that meticulous control of maternal carbohydrate and fat metabolism before and during pregnancy in women with diabetes mellitus had positive benefits for the offspring, not only by reducing the incidence of congenital malformations, but also by diminishing fetal loss, reducing immediate neonatal complications and, in the long term, reducing unnecessary obesity, improving neuropsychological development and reducing the emergence of diabetes in the offspring at a relatively early age. Women who develop GDM are at a significant risk of developing NIDDM, and prevention of obesity, consumption of a high-fibre diet and possibly prophylactic hypoglycaemic therapy may reduce this otherwise inevitable progression, which will affect at least 50%.

Incidence and severity of gestational diabetes mellitus according to country of birth in women living in Australia

Gestational diabetes mellitus (GDM) was diagnosed in 1928 of 35,253 (5.5%) tested pregnancies at the Mercy Maternity Hospital in Melbourne between 1979 and the end of 1988. Compared with women born in Australia and New Zealand, the incidence of GDM was significantly greater in women born on the Indian subcontinent (15%); in women born in Africa (9.4%), Vietnam (7.3%), Mediterranean countries (7.3%), and Egypt and Arabic countries (7.2%); and in Chinese (13.9%) and other Asian (10.9%) women. There was no significant difference for women born in the United Kingdom and northern Europe (5.2%), Oceania (5.7%), North America (4.0%), or South America (2.2%). With the World Health Organization criteria as a guide to the severity of hyperglycemia, compared with mothers born in Australia and New Zealand, there were significant increases in the incidences of the more severe grades of GDM in parturients born in the Mediterranean region, Asia, the Indian subcontinent, Egypt, and Arabic countries. The incidence of GDM increased significantly in all racial groups, rising from 3.3% during 1979-1983 to 7.5% during 1984-1988.

Obstetrical management of patients with diabetes in pregnancy

The management of the woman with diabetes diagnosed before the onset of pregnancy, or who develops it during pregnancy, requires a team approach involving the woman and her partner, the diabetes nurse educator, the dietitian, the endocrinologist, the obstetrician, the ultrasonologist and the paediatrician. It should start before pregnancy so that normoglycaemia is achieved before conception and maintained throughout gestation and labour. Fetoplacental surveillance commences with an early ultrasound to confirm fetal viability, repeated around 20 weeks to exclude major fetal malformations and then later in the third trimester to monitor fetal growth. CTG and biophysical profile assessment are major adjuncts to ensuring fetal well-being. The pregnancy should be allowed to go to full term when maternal blood glucose control has been satisfactory, fetal growth is within the normal range and other obstetrical complications, e.g. pre-eclampsia, are absent. Such an approach will ensure that the caesarean section rate can be minimized. During labour, the progress of labour and fetal well-being should be closely monitored. The woman who has microvascular complications of her diabetes (including proliferative retinopathy and nephropathy) requires even closer surveillance and premature delivery is more likely to be needed. The principles of management of the woman who develops gestational diabetes are similar, with even greater emphasis being placed on not inducing labour before full term unless complications dictate otherwise.

The persistence of abnormal glucose tolerance after delivery

In the first 7 days after delivery, 270 women who had gestational diabetes and 100 who had normal prenatal glucose tolerance were retested for glucose intolerance. In the group who had gestational diabetes, glucose tolerance remained abnormal by the Mercy Maternity Hospital criterion in 28% of those who had been delivered vaginally and in 43% of those delivered by cesarean. The only abnormal test in the control group was in one of the two women delivered by cesarean, and this test returned to normal by the seventh postoperative day. By 6 weeks postpartum, the incidence of abnormal glucose tolerance was 24 and 30% for patients having vaginal and abdominal deliveries, respectively. The method of infant feeding had no significant influence on the prevalence of abnormal glucose tolerance. We conclude that if a glucose tolerance test has not been performed prenatally, the test is still worthwhile in the immediate puerperium if the possibility of gestational diabetes has been raised by adverse pregnancy outcome, because about one in three diabetics will be thus identified. However, screening in the puerperium is not a substitute for prenatal screening.

Effect on pregnancy on gallstone formation

An ultrasound study was carried out to determine the incidence of gallstone formation during pregnancy. One hundred and thirty seven pregnant women attending antenatal clinics were studied; 70 women were primigravidas and 67 were 1 para or more. An ultrasound of the gallbladder was carried out at 20 weeks or less of gestation and a repeat of ultrasound examination was performed soon after delivery. Five women had gallstones diagnosed before pregnancy; 1 of these was a primigravida, the other 4 were para 1 or more. None of the women developed gallstones during pregnancy. This finding suggests that pregnancy is unlikely to be an important factor in gallstone formation.

Survey of hand symptoms in pregnancy

In a study of 1216 pregnancies, 427 (35%) patients reported hand symptoms. Symptoms of the same quality and distribution were reported by 40 (30%) of 132 control subjects within the previous year, and although invariably mild, these symptoms suggest that pregnancy may aggravate a pre-existing condition. Fewer than 20% of the 427 affected patients described a classic median-nerve symptom distribution (carpal tunnel syndrome), while 12% of patients described an ulnar-nerve distribution, which is thought to represent a genuine and previously underestimated occurrence of ulnar-nerve neuropathy in pregnancy. In 69% of patients, hand symptoms were generalized. Most symptoms were bilateral, commenced in the third trimester and resolved soon after delivery. There was a significant correlation of hand symptoms in pregnancy with the presence of preeclampsia, tight rings, the weight at confinement, the birth weight and a history of premenstrual bloating. Operative intervention was not required for any patient.

Antepartum cardiotocography--an audit

Between 1981 and 1986, 9,840 women were monitored by antepartum nonstressed cardiotocography (CTG). A satisfactory fetal reserve pattern was detected in 91%, a reduced reserve pattern in 8% and a critical reserve pattern in 1%. The incidences of fetal growth retardation, Apgar score less than 6 at 1 minute, perinatal mortality and Caesarean section all increased significantly (p less than 0.001) as the degree of cardiotocographic fetal reserve worsened. Intrauterine growth retardation and/or low urinary oestriol excretion was associated with a highly significantly increased incidence of abnormal CTG traces (14.2%, p less than 0.001). A satisfactory fetal reserve pattern on cardiotocography was a reliable predictor of fetal well-being, since after exclusion of lethal malformations, the perinatal mortality rate in those patients monitored within 7 days of delivery was 3/1,000.

Preeclampsia in twin pregnancy--severity and pathogenesis

The incidence of preeclampsia in a consecutive series of 642 twin pregnancies was 25.9% compared with 9.7% in singleton pregnancies (p less than 0.001); in primiparas it was 35.2% and in multiparas 20.4% (p less than 0.001). Preeclampsia in twin pregnancies was more commonly of early onset (p less than 0.001) and the maternal disease more severe as assessed by the incidences of severe hypertension (p less than 0.001), proteinuria (p less than 0.004), and eclampsia (p less than 0.01). There were 1 maternal and 12 perinatal deaths. Oestriol excretion before the emergence of preeclampsia was lower in patients with severe compared with milder preeclampsia (p less than 0.05) as was plasma glucose concentration (p less than 0.05). Mean birth and placental weights according to gestation, tended to be lower in the severe group compared with uncomplicated cases and those with milder preeclampsia, as were also the placental-fetal weight ratios. The similarity of results with those already reported for singleton pregnancy suggested a similar pathogenesis for preeclampsia in twin and singleton pregnancies.

Timely diagnosis by cardiotocography of critical fetal reserve due to fetofetal transfusion syndrome

In a review of 90 twin pregnancies monitored by antenatal cardiotocography there were 8 cases of subsequently proven fetofetal transfusion syndrome. In 2 of these evidence of severe fetal stress had indicated immediate delivery; the 4 babies survived in circumstances that were perilous. In 1 case there was no evidence of critical fetal reserve but the recipient twin died, this probably representing an acute fetofetal transfusion during labour. In the 5 milder cases with no evidence of stress on cardiotocography, all babies survived and they required minimal or no treatment for problems relating to the fetofetal transfusion. In multiple pregnancy the cardiotocograph offers the additional bonus of detection of fetal compromise due to fetofetal transfusion.

The long-term follow-up of women with gestational diabetes

Four hundred and forty-seven women who had gestational diabetes have been retested at intervals from 1 to 12 years following diagnosis; 49 (11%) were found to be diabetic and 35 (7.8%) had impaired glucose tolerance using the WHO criteria. An abnormal glucose tolerance test in the puerperium and obesity at the time of retesting had significant associations with abnormal glucose tolerance at follow-up. However, the best predictive factor of the likelihood of the development of significant hyperglycaemia was the recurrence of gestational diabetes in a subsequent pregnancy, since 28% of these women were diabetic and a further 4% had impaired glucose tolerance at the time of follow-up. These findings indicate that the criteria used for the diagnosis of gestational diabetes at the Mercy Maternity Hospital, Melbourne (1-hour greater than or equal to 9 mmol/l together with a 2-hour greater than or equal to 7 mmol/l) are appropriate for an Australian population.

Histocompatibility antigens and intrauterine fetal growth retardation

Maternal-fetal antigen compatibility adversely affects fetal and placental weights in animal experiments and is associated with recurrent spontaneous abortion and preeclampsia in human reproduction. HLA A and B types of the mother, father and infant were determined in 30 pregnancies complicated by intrauterine fetal growth retardation (IUGR) and in 32 normal pregnancies. The frequency and degree of antigenic compatibility between the parents and the mothers and their infants were compared between the groups. There was no evidence that IUGR was associated with a significant degree of HLA A and B antigenic compatibility.

Nonstressed antepartum cardiotocography in patients undergoing elective cesarean section--fetal outcome

In a prospective study of 409 patients monitored with nonstressed antepartum cardiotocography and delivered by elective cesarean section, cardiotocography was requested for 170 because of clinical indications. This group had higher incidences of abnormal cardiotocography (p less than 0.001), fetal growth retardation (p less than 0.001) and neonatal deaths (p less than 0.025) than had the group without such requests, suggesting that clinicians effectively selected the high-risk pregnancy for testing of fetal well-being. Cardiotocographic evidence of critical reserve was found in 17 of 170 patients (10%) tested for a clinical indication and in none of the 239 patients in the control group. Patients with abnormal cardiotocography results had significantly higher incidences of cord arterial blood pH less than 7.26 (p less than 0.05) and Apgar scores of less than 6 at 1 minute (p less than 0.001), showing that an abnormal cardiotocogram is indicative of a fetus at risk of having hypoxia.

The outcome of pregnancies complicated by narcotic drug addiction

The incidence of known narcotic drug addiction at 2 Maternity Hospitals in Melbourne was 0.06% (45 of 80,950 confinements). The obstetric results of these 45 pregnancies were unexpectedly favourable, the main complications being fetal growth retardation (27%) and premature birth before 37 weeks (27%). There were no fetal malformations and only 1 perinatal death. Follow-up information is necessary to ascertain if the main hazard to these infants lies in the environment to which they return.

Quality of survival of infants with critical fetal reserve detected by antenatal cardiotocography

During the 8-year period 1973 to 1980, antenatal cardiotocographic monitoring was performed on 3,006 high-risk pregnancies selected from a total obstetric population of 37,856 patients. A critical fetal reserve was detected in 72 patients (2.3%) whose pregnancies resulted in 20 perinatal deaths and 52 infants who survived the neonatal period; 45 of these infants have been assessed at ages ranging from 2 months to 8 years, 9 months. Growth was below the tenth percentile in 25.0% for weight, 23.3% for length, and 22.5% for head circumference at the review examination. Neurological abnormalities were detected in 12 infants but the abnormality was major in only four, including one who has familial interstitial polyneuropathy. The quality of survival of infants delivered of pregnancies complicated by critical fetal reserve is satisfactory; 93.2% had no neurological impairment likely to interfere with quality of life and indeed 13.5% had superior intelligence. Cardiotocographic evidence of critical fetal reserve does not signify that the fetus is doomed; delivery by cesarean section is indicated if the fetus is viable and has no ultrasonic evidence of untreatable major malformation.

Whole blood viscosity in preeclampsia

Whole blood viscosity was measured in 41 patients with preeclampsia and in 51 normotensive control subjects. The mean viscosity in the preeclamptic group had a highly significant elevation (t = 9.752, p less than 0.001, at a shear rate of 0.1 sec-1 and t = 4.223, p less than 0.001, at a shear rate of 100 sec-1). The slower shear rate gave the better discrimination between the two groups as only four patients with preeclampsia had a value within 1 SD of the mean of the control group. It is suggested that the measurement of whole blood viscosity may be clinically useful in the management of patients with preeclampsia.

Angiotensin-converting enzyme and the renin-angiotensin system in normotensive primigravid pregnancy

In a prospective study the interactions between ACE and the renin-angiotensin system in 18 primigravid normotensive women were investigated throughout pregnancy. ACE activity was found to be depressed throughout pregnancy, rising in the last trimester and returning to non-pregnant values by 6 weeks post partum. No significant differences were found between cord arterial or venous and maternal venous ACE levels at delivery. ACE was inversely related to systolic and mean arterial blood pressures, inversely to serum sodium and urinary potassium and directly to serum potassium levels. Within the system, ACE was correlated only to aldosterone levels. In company with other components of the system ACE activity appears to be altered in pregnancy and to be influenced by similar control mechanisms. It is possible that ACE plays a modulating role on aldosterone secretion via the (des-asp1), Angiotensin I pathway.

A prospective study of plasma angiotensin-converting enzyme in normotensive primigravidae and their infants

Plasma angiotensin-converting enzyme (ACE) has been measured prospectively throughout pregnancy, at delivery and in the puerperium in 18 normotensive primigravidae and their infants. Plasma ACE was consistently lower during pregnancy than in comparable, non-pregnant controls, but rose progressively from about 30 weeks to term. At vaginal delivery maternal and fetal ACE levels did not differ significantly. There was a steady increase in maternal ACE activity up to 6 weeks post partum, when the levels were not significantly different from non-pregnant controls. No correlation could be found between plasma ACE and plasma renin activity or concentration, or plasma AII. Plasma aldosterone increased in parallel with ACE during the last ten weeks of pregnancy.

Labour-onset pre-eclampsia

In a consecutive series of 1,201 singleton pregnancies with pre-eclampsia, the onset occurred during labour in 290 (24.1%). There was no difference between the primiparous and parous patient in this respect (25.9% v 20.7%; P less than 0.10). The tendency for pre-eclampsia to develop during labour increased with advancing maturity of the pregnancy and seldom occurred before 38 weeks of gestation; this was again equally true of the primiparous and parous patient, as was the incidence of severe hypertension (diastolic pressure greater than 110mm Hg) (36.1% v 34.1%). The high incidences of severe hypertension (35.5%), proteinuria (41.7%), and eclampsia (2.1%), and the 1 maternal death testified to the severity of the disease process and the need for aggressive management. After delivery, the clinical signs tended to subside rapidly, but the early third stage of labour was a time of maternal risk, irrespective of whether ergometrine or Syntocinon was the oxytocic agent administered. Analysis of perinatal results showed that the risk to the fetus was minimal.

Maternal glucose tolerance during pregnancy with excessive size infants

A study of maternal glucose tolerance conducted during 137 pregnancies in which the infant weighed 4540 g or more at birth revealed an increased incidence of hyperglycemia (20.4% P less than 0.01). Only when a birth weight of more than the 99th percentile was considered was a significant association with maternal hyperglycemia evident. However, 105 of the 137 patients (77%) had normal glucose tolerance, which indicated that hyperglycemia is not necessarily the cause of fetal overgrowth. When a woman delivers an infant with a birth weight of 4540 g or more, it cannot be assumed that she was a gestational diabetic.

Effects of ketamine on the pregnant uterus

Intra-uterine pressure was recorded by placing a Foley catheter in the extra-amniotic space before the termination of pregnancy in 25 patients, and Caesarean section in 12 patients. The effects of administration of i.v. ketamine 2 mg/kg body weight, sodium thiopentone 4 mg/kg body weight and ergometrine 0.5 mg, and intra-cervical 0.5% lignocaine 20 ml were measured in the first trimester of pregnancy, and i.v. ketamine and sodium thiopentone in late pregnancy. Ketamine was found to cause uterine contraction (mean increase 16.1 mm Hg) equal to ergometrine (mean increase 14.8 mm Hg) in early pregnancy, but exert no effect (mean decrease -- 1.33 mm Hg) in late pregnancy. Lignocaine in early pregnancy given as a paracervical block had no significant effect on intrauterine pressure (mean increase 0.33 mm Hg). Sodium thiopentone (mean decrease -- 4.28 mm Hg first trimester and -- 2.22 mm Hg at term) in late pregnancy had no significant effect on intra-uterine pressure.