Can changes in angiogenic biomarkers between the first and second trimesters of pregnancy predict development of pre-eclampsia in a low-risk nulliparous patient population?

OBJECTIVE

To determine if change in maternal angiogenic biomarkers between the first and second trimesters predicts pre-eclampsia in low-risk nulliparous women.

DESIGN

A nested case-control study of change in maternal plasma soluble Flt-1 (sFlt-1), soluble endoglin (sEng) and placenta growth factor (PlGF). We studied 158 pregnancies complicated by pre-eclampsia and 468 normotensive nonproteinuric controls.

SETTING

A multicentre study in 16 academic medical centres in the USA.

POPULATION

Low-risk nulliparous women.

METHODS

Luminex assays for PlGF, sFlt-1 and sEng performed on maternal EDTA plasma collected at 9-12, 15-18 and 23-26 weeks of gestation. Rate of change of analyte between first and either early or late second trimester was calculated with and without adjustment for baseline clinical characteristics.

MAIN OUTCOME MEASURES

Change in PlGF, sFlt-1 and sEng.

RESULTS

Rates of change of PlGF, sEng and sFlt-1 between first and either early or late second trimesters were significantly different in women who developed pre-eclampsia, severe pre-eclampsia or early-onset pre-eclampsia compared with women who remained normotensive. Inclusion of clinical characteristics (race, body mass index and blood pressure at entry) increased sensitivity for detecting severe and particularly early-onset pre-eclampsia but not pre-eclampsia overall. Receiver operating characteristics curves for change from first to early second trimester in sEng, PlGF and sFlt-1 with clinical characteristics had areas under the curve of 0.88, 0.84 and 0.86, respectively, and for early-onset pre-eclampsia with sensitivities of 88% (95% CI 64-99), 77% (95% CI 50-93) and 77% (95% CI 50-93) for 80% specificity, respectively. Similar results were seen in the change from first to late second trimester.

CONCLUSION

Change in angiogenic biomarkers between first and early second trimester combined with clinical characteristics has strong utility for predicting early-onset pre-eclampsia.

Vitamin D status and recurrent preterm birth: a nested case-control study in high-risk women

OBJECTIVE

To determine whether vitamin D status is associated with recurrent preterm birth, and any interactions between vitamin D levels and fish consumption.

DESIGN

A nested case-control study, using data from a randomised trial of omega-3 fatty acid supplementation to prevent recurrent preterm birth.

SETTING

Fourteen academic health centres in the USA.

POPULATION

Women with prior spontaneous preterm birth.

METHODS

In 131 cases (preterm delivery at <35 weeks of gestation) and 134 term controls, we measured serum 25-hydroxyvitamin D [25(OH)D] concentrations by liquid chromatography-tandem mass spectrometry (LC-MS) from samples collected at baseline (16-22 weeks of gestation). Logistic regression models controlled for study centre, maternal age, race/ethnicity, number of prior preterm deliveries, smoking status, body mass index, and treatment.

MAIN OUTCOME MEASURES

Recurrent preterm birth at <37 and <32 weeks of gestation.

RESULTS

The median mid-gestation serum 25(OH)D concentration was 67 nmol/l, and 27% had concentrations of <50 nmol/l. Serum 25(OH)D concentration was not significantly associated with preterm birth (OR 1.33; 95% CI 0.48-3.70 for lowest versus highest quartiles). Likewise, comparing women with 25(OH)D concentrations of 50 nmol/l, or higher, with those with <50 nmol/l generated an odds ratio of 0.80 (95% CI 0.38-1.69). Contrary to our expectation, a negative correlation was observed between fish consumption and serum 25(OH)D concentration (-0.18, P < 0.01).

CONCLUSIONS

In a cohort of women with a prior preterm birth, vitamin D status at mid-pregnancy was not associated with recurrent preterm birth.

Imatinib mesylate and metabolite concentrations in maternal blood, umbilical cord blood, placenta and breast milk

Treatment of maternal chronic myeloid leukemia with imatinib mesylate is avoided because of potential fetal effects. Two women with progression of disease during pregnancy required imatinib therapy. Concentrations of imatinib in maternal blood, placenta, umbilical cord blood and breast milk were 886, 2452, 0 to 157, and 596 ng/ml, respectively. Concentrations of the active metabolite CGP74588 in maternal blood, placenta, umbilical cord blood and breast milk were 338, 1462, 0 and 1513 ng/ml, respectively. As Imatinib and CGP74588 cross the mature placenta poorly, use of the drug after the first trimester may be reasonable under some circumstances. Imatinib and CGP74588 are found in breast milk, and therefore avoidance of breastfeeding is advisable.

Amniotic fluid insulin at 14-20 weeks' gestation: association with later maternal glucose intolerance and birth macrosomia

OBJECTIVE

To examine the hypothesis that early second trimester amniotic fluid (AF) insulin concentration is elevated and later fetal growth is augmented in gravidas demonstrating later oral glucose intolerance.

RESEARCH DESIGN AND METHODS

In this prospective observational cohort study, AF was sampled at 14-20 weeks' gestation in 247 subjects, and 1-h 50-g oral glucose challenge tests (GCTs) were performed at > or = 24 weeks. AF insulin was assayed by an automated immuno-chemiluminometric assay (8). Macrosomia was defined as birth weight above the 90th centile.

RESULTS

AF insulin concentration (range 1.4-44.5 pmol/l) correlated positively with gestational age and maternal weight. A logistic regression analysis, adjusted for maternal age and midpregnancy weight, showed increased AF insulin multiples of gestational age-specific medians to be associated with subsequently diagnosed gestational diabetes mellitus (GDM) (OR 1.9, CI 1.3-2.4, P = 0.029). Among 60 subjects with GCT values > 7.2 mmol/l, each unit increase in AF insulin multiple of median (MOM) was associated with a threefold increase in fetal macrosomia incidence (3.1, 1.3-4.9, P = 0.048).

CONCLUSIONS

An elevated AF insulin concentration at 14-20 weeks' gestation is associated with subsequently documented maternal glucose intolerance. Among gravidas with GCT values > 7.2 mmol/l, elevated early AF insulin concentration is associated with fetal macrosomia. Maternal glucose intolerance may affect fetal insulin production before 20 weeks' gestation.

Midpregnancy serum C-peptide concentration and subsequent pregnancy-induced hypertension

OBJECTIVE

To test the hypothesis that elevated midpregnancy serum insulin (IRI) and C-peptide (CP) concentrations are associated with later development of pregnancy-induced hypertension (PIH), independent of prepregnancy obesity and midpregnancy blood pressure.

RESEARCH DESIGN AND METHODS

In this prospective study, a cohort of normotensive women, ages > or = years performed a 50-g glucose challenge test at 24-30 weeks' gestational age. Blood samples were collected after an overnight fast and 1 h after glucose ingestion. Serum IRI and CP concentrations were measured in each sample. Maternal height, blood pressure and proteinuria were measured at the time of glucose challenge testing and after 36 weeks' gestational age.

RESULTS

Of 320 subjects enrolled 44 women (13.8%) had subsequent PIH. Crude odds ratios (ORs) for devevelopment of PIH associated with each 1 U rise in log fasting IRI, log lasting CP. and glucosed-induced increase in CP (expressed as log [postprandial CP/fasting CP]) were 2.0 (95% CI 1.3-3.3), 1.8 (CI 1.2-2.7), and 2.3 (CI 1.1-4.9) respectively. After controlling for prepregnancy BMI, gestational age, and midpregnancy mean arterial pressure, adjusted ORs corresponding to log fastig IRI and CP for the development of PIH were 1.3 (95% CI 0.7-2.3) and 1.7 (CI 1.1-2.7) respectively, and, afterq adjustment for fasting CP, the adjusted OR of the glucose-induced rise in log CP was 3.7 (CI 1.5-9.3).

CONCLUSIONS

Mid-pregnancy tasting and postoral glucose CP levels are associated with subsequent development of PIH, independent of maternal obesity and midpregnancy baseline blood pressure. These findings many reflect an amplified beta3-cell response to glycemic stimulus, similar to that found in states of insulin resistance, that appears to be independently associated with PIH.

Glucocorticoid-associated maternal hyperglycemia: a randomized trial of insulin prophylaxis

OBJECTIVES

To study the degree and timing of maternal hyperglycemia following betamethasone therapy in nondiabetic patients and establish a prophylactic dose of insulin.

METHODS

Forty-five patients receiving betamethasone 12 mg i.m. at 7 AM on two consecutive days were randomized to no insulin (n = 20), low-dose insulin (n = 18), and high-dose insulin (n = 7) protocols. Each treatment group received s.c. insulin at 7 AM on the 2 days of betamethasone therapy (20 units NPH/10 units regular, and 40 units NPH/20 units regular, respectively). Capillary plasma glucose measurements were obtained at fasting and 2 h after meals for 3 days. A multivariate normal regression model was used to estimate and compare mean glucose levels.

RESULTS

Eighty-five percent of patients who did not receive insulin exhibited hyperglycemia at levels previously associated with fetal acidosis. Significant differences in mean postprandial plasma glucose levels were found between the no-treatment and insulin groups on days 1 and 2. No significant differences were noted between groups on day 3.

CONCLUSIONS

Transient maternal hyperglycemia occurs in a consistent pattern in nondiabetic patients receiving betamethasone, which can be limited by the concurrent use of insulin. Further studies to assess fetal acidosis in this setting are warranted.

Outcome of very low birth weight infants with histopathologic chorioamnionitis

OBJECTIVE

To determine neonatal outcome at 7 months of corrected age in very low birth weight (VLBW) infants with placental chorioamnionitis.

METHODS

We conducted a cohort study of 287 VLBW infants delivered as a result of preterm premature rupture of membranes (PROM) or preterm labor. Control subjects (n = 123) had placentas with absent umbilical cord inflammation and absent or low-grade membrane inflammation. Case subjects (n = 164) had moderate membrane inflammation or any umbilical cord inflammation. Neonatal and 7-month outcomes were compared. A power analysis showed that 98 total subjects were needed to reject the two-sided null hypothesis with a difference in mean Bayley index scores of at least 8.

RESULTS

Infants in the study group had significantly more preterm PROM, antenatal antibiotics, lower birth weight, lower gestational age, longer duration of ruptured membranes, and clinical chorioamnionitis. Intraventricular hemorrhage occurred more commonly in infants with placentas demonstrating chorioamnionitis (relative risk = 1.6, 95% confidence interval 1.1, 2.4, P =.013). One hundred sixty-seven (69%) of the 243 surviving infants had 7-month follow-up. There was no difference between cases and controls in mean Bayley mental developmental index (93 compared with 90, P =.25), psychomotor developmental index (89 compared with 90, P =.68), or in the number of infants that were developmentally delayed.

CONCLUSION

Despite a higher frequency of intraventricular hemorrhage, no difference in developmental scores was detected at 7 months of corrected age in VLBW infants with histologic chorioamnionitis.

Lethal fetal renal anomalies and obstetric outcome

The incidence of prenatal and intrapartum complications was examined among 33 pregnancies complicated by lethal fetal renal abnormalities (cases) and compared to 200 contemporaneous control pregnancies (controls) by retrospective record review. Cases experienced higher rates of antepartum bleeding (29% vs. 6%, p<0.0001) stillbirth (15% vs. 0%, p<0.0001), preterm birth (34.3+/-4.1 vs. 39.7+/-1.8, p<0. 0001) and breech presentation (48% vs. 4%, p<0.0001). Twenty-six of 33 cases had lung weights </= first centile. Primary cesarean section occurred more frequently in cases than in controls (48% vs. 9%, p<0.0001). Knowledge of poor fetal prognosis alone did not appear to influence obstetrical management. We conclude that timely consultation with sonologist and neonatologist and patient counseling may avoid unnecessary obstetrical intervention when pregnancy complications occur. Pregnancies complicated by lethal fetal renal abnormalities have higher rates of ante- and intrapartum complications leading to frequent abdominal delivery. This suggests that accurate predictive markers for lethal fetal renal disease may reduce ineffective obstetric intervention.

A high-sensitivity assay for amniotic fluid insulin at 14-20 weeks' gestation

OBJECTIVE

To examine sensitivity, precision, and sample stability of an immunochemiluminomimetric insulin assay in 14-20 week amniotic fluid (AF) and fetal age distribution of second-trimester AF insulin concentrations.

METHODS

We assayed fresh specimens from 576 gravidas who had amniocentesis at 14-20 weeks' gestation because of maternal age. In a preliminary study, samples were divided into aliquots and stored at 4C and -20C for 24 hours to assess freezing effect. Some samples stored at 4C were assayed repeatedly during a 14-day period and others, stored at -20C, were assayed after a 70-day period.

RESULTS

This assay reliably measured AF insulin to a detection limit of 0.03 microIU/mL. Insulin could be measured in all amniotic fluid samples and demonstrated a log10 Gaussian distribution, ranging from 0.24 to 7.41 microIU/mL. Interassay coefficients of variation ranged from 4.4 to 8.9% at concentrations of 0.4-2.0 microIU/mL. Linearity of dilution from 1.5 to 10 times was 99.2 +/- 8.6%. Spike recovery of 10 microIU/mL was from 92-109%. Recovery after freezing to -20C for 24 hours (101%) and 70 days (97%) and after storage at 4C for 14 days (97%) demonstrated no significant loss.

CONCLUSION

A two-site, dual monoclonal, immunochemiluminomimetric insulin assay was sufficiently sensitive and precise within the lower range of measured AF insulin concentrations to investigate clinical associations of 14-20 week AF insulin with maternal and fetal conditions. The insulin stability in this matrix suggests that assays can be reliable on specimens stored up to 70 days.

Influence of chorioamnionitis on developmental outcome in very low birth weight infants

OBJECTIVE

To determine the effect of exposure to chorioamnionitis on developmental outcome in very low birth weight (VLBW) infants.

METHODS

Five hundred four maternal charts (97% of all VLBW infants delivered from 1990 to 1994) were reviewed. A historical cohort study of the 330 infants delivered secondary to preterm premature rupture of membranes or preterm labor was performed. Case subjects (71) were delivered of mothers with chorioamnionitis by clinical criteria; control subjects (259) were delivered of mothers without chorioamnionitis. Bayley index scores at 7 months' corrected age and special care nursery outcomes were compared. One hundred seventy-three subjects were necessary to reject the two-sided null hypothesis with 80% power with a difference in mean Bayley index scores of at least 8.

RESULTS

Neonatal sepsis (8.5% compared with 1.9%; odds ratio [OR] = 4.7, 95% confidence interval [CI] 1.4, 15.9, P = .015) and a low 5-minute Apgar (72% compared with 55%; OR = 2.1, CI 1.2, 3.8, P = .012) occurred more frequently in the chorioamnionitis group. One hundred eighty-seven (68%) of 273 surviving neonates had follow-up. Cases and controls were similar in mean Bayley mental developmental index (91.2 compared with 91.8, P = .84), Bayley psychomotor developmental index (89.8 compared with 89.1, P = .82), and number of infants developmentally delayed. Duration of exposure to chorioamnionitis did not affect neonatal outcome.

CONCLUSION

Despite higher rates of sepsis and low Apgar scores, no difference in outcome at 7 months of corrected age was detected in VLBW infants exposed to chorioamnionitis. Contemporary neonatal management may reduce the adverse effects of this exposure.

The effect of pregnancy on the natural history of diabetic retinopathy and nephropathy

Retinopathy and nephropathy are complications of diabetes mellitus that can affect women of reproductive age. This article focuses on the effect of pregnancy on the risk of progression of microvascular disease, both during gestation and at long-term follow-up. Fortunately, with intensive medical surveillance and appropriate interventions, most women with types 1 and 2 diabetes mellitus can be offered an optimistic prognosis for child bearing.

The diagnosis of gestational diabetes

The concept of gestational diabetes goes back at least to 1946. Over the years, sophistication has increased regarding the pathophysiology of this condition. However, there is not universal agreement on how to diagnose gestational diabetes. The most widely used diagnostic criteria in the U.S. were validated by their predictive value for subsequent diabetes in the mother, rather than by their ability to identify risk to the fetus and newborn. The best available evidence supports the notion that the relationship between carbohydrate intolerance in pregnancy and adverse perinatal outcomes is a continuous one, and no single cutoff can separate pregnant women into those with high risk and those with no risk at all. Suggestions are made for arriving at appropriate, albeit arbitrary, diagnostic criteria.

The relationship between second-trimester amniotic fluid insulin and glucose levels and subsequent gestational diabetes

Associations between elevated amniotic fluid glucose and insulin levels in the second trimester and the subsequent development of gestational diabetes have been reported. We conducted a case-control study to determine which analyte best predicts future maternal glucose intolerance. Thirty-nine women diagnosed with gestational diabetes (criteria of Carpenter and Coustan, Am. J. Obstet. Gynecol., 144, 768, 1982) who had undergone genetic amniocentesis for advanced maternal age were matched with euglycaemic controls. Glucose and insulin concentrations were determined by analysis of stored amniotic fluid samples. No significant difference was detected between cases and controls for amniotic fluid glucose concentrations. Amniotic fluid insulin concentrations were significantly higher in cases (mean rank 4.44, P < 0.01, using matched rank analysis of variance, where 1 is the lowest and 6 is the highest rank). After conversion to multiples of the median, 20 per cent of women with subsequent gestational diabetes were found to have amniotic fluid glucose levels at or above the 90th centile, while 35 per cent of cases had similarly elevated amniotic fluid insulin levels. We conclude that second-trimester amniotic fluid insulin is a more sensitive predictor of impending glucose intolerance than amniotic fluid glucose, although neither is sufficiently powerful to use alone as a screening test.

Positional effects on maternal cardiac output during labor with epidural analgesia

OBJECTIVE

Our purpose was to test the hypothesis that the supine versus the lateral position is associated with a greater decrement in cardiac output after epidural analgesia in labor.

STUDY DESIGN

Twenty-one normal term subjects were randomized to the left lateral or supine position in early labor. Cardiac output measured by the acetylene rebreathing method, stroke volume, heart rate, mean arterial pressure, and systemic vascular resistance were obtained at 5-minute intervals, beginning before a 500 ml intravenous fluid bolus (baseline) and ending 45 minutes after epidural injection.

RESULTS

Mean baseline supine versus lateral group differences were significant for 21% lower cardiac output, 21% lower stroke volume, 19% higher mean arterial pressure, 50% higher systemic vascular resistance, and equivalent heart rate. In the supine group fluid bolus resulted in significantly increased cardiac output and stroke volume, decreased mean arterial pressure and systemic vascular resistance, and unchanged heart rate. In the supine group cardiac output and stroke volume decreased significantly after epidural injection. The lateral position group exhibited no hemodynamic alterations after fluid bolus or epidural.

CONCLUSIONS

In contrast to the lateral position, the supine position is associated with a significant postepidural decrement in cardiac output, not identified by a change in heart rate. This likely reflects an inability to maintain stable preload volume in the supine position.

Exercise fails to improve postprandial glycemic excursion in women with gestational diabetes

The effect of an acute period of moderate intensity exercise on maternal glycemic excursion following a mixed nutrient meal was studied. Five normal (NL) and six gestational diabetic (GDM) subjects were enrolled. A randomized crossover design was used to compare fasting glucose and insulin levels, peak glucose and insulin levels and incremental area of the glycemic and insulin curves following a mixed nutrient meal with or without an exercise stress that took place 14 h earlier. Exercise consisted of upright stationary cycling for 30 min at a heart rate consistent with 60% VO2max. The clinical characteristics of normal and gestational diabetic subjects were comparable. Mean values (+/-SEM) with, versus without, exercise for fasting glucose (NL: 78.9 +/- 2.6 vs. 80.0 +/- 2.6 mg/dl; GDM: 86.4 +/- 2.0 vs. 82.1 +/- 3.5 mg/ dl), peak glucose (NL: 132.3 +/- 10.4 vs. 139.1 +/- 15.6 mg/dl; GDM: 165.8 +/- 5.5 vs. 160.3 +/- 7.8 mg/dl), the area under the glycemic curve (NL: 5758 +/- 1038 vs. 6393 +/- 1281 mg/dl.min; GDM: 8,178 +/- 890 vs. 8,331 +/- 563 mg/dl.min) did not differ. Similarly, plasma insulin levels did not differ between protocols for either group of subjects. Exercise has been proposed as a treatment to reduce glycemia in gestational diabetes. Results from this study indicate a single bout of exercise did not blunt the glycemic response observed following a mixed nutrient meal.

Glucose and lactate kinetics during a short exercise bout in pregnancy

Pregnancy is considered diabetogenic. Although exercise has been advocated to assist in metabolic control of the nonpregnant diabetic individual, there is a paucity of data about the metabolic effects of exercise during pregnancy. To examine whether moderate exertion may be beneficial in the maintenance of maternal carbohydrate homeostasis, glucose and lactate kinetics were measured in the third trimester in five pregnant nondiabetic women (gestational age, 34.2 +/- 0.1 weeks [mean +/- SE]) by infusion of 45 microg x kg(-1) x min(-1) [6,6-2H2]glucose and 70 microg x kg(-1) x min(-1) [U-13C]lactate tracers. Subjects were observed at rest for determination of baseline steady-state kinetics over a 30-minute period, and then they exercised for 30 minutes at 60% maximum oxygen consumption (VO2max) and were evaluated for 30 minutes postexercise. Glucose and lactate kinetics and lactate oxidation were measured throughout the exercise protocol. This study was repeated postpartum in all individuals at least 6 weeks after delivery. Compared with the steady-state preinfusion period, plasma glucose concentration was not elevated during exercise in either group, nor was plasma lactate concentration significantly different in either group. Glucose kinetics did not change during exercise, but lactate kinetics increased in both groups. V02 and percent of lactate C contribution to CO2, an indication of lactate oxidation, increased proportionally in both groups during exercise. Metabolic perturbations, as measured by glucose and lactate kinetics, do not appear to be different during the third trimester of pregnancy during a relatively short bout of exercise compared with the nonpregnant state.

Fetal hyperinsulinism at 14-20 weeks and subsequent gestational diabetes

OBJECTIVE

To examine the predictive value of amniotic fluid (AF) insulin at 14-20 weeks' gestation for subsequent gestational diabetes and macrosomia in unselected gravidas 35 years or older at time of genetic amniocentesis.

METHODS

We identified 296 pregnancies through stored AF samples from genetic amniocenteses (collected March 1987 through August 1992) in women meeting the following criteria: age 35 years or older, amniocentesis at 14-20 weeks, performance of a 50-g glucose challenge test, and adequate delivery data.

RESULTS

A modified double-antibody radioimmunoassay reliably measured AF insulin with a detection limit of 0.35 microU/mL. Pregnant women in whom gestational diabetes was later diagnosed had higher median AF insulin levels than women who did not (0.60 versus 0.42 microU/mL, respectively; P = .026). A stepwise logistic regression analysis of gestational age at amniocentesis, maternal second-trimester weight, maternal age, and log AF insulin value on gestational diabetes showed only AF insulin to have a significant association with gestational diabetes (P = .004). Seven of 21 cases of gestational diabetes had AF insulin values exceeding the 95th percentile (1.33 microU/mL) compared with only 14 of 275 women with normal glucose tolerance (P < .001). Amniotic fluid insulin did not predict macrosomia in either nondiabetic or gestational diabetic pregnancies.

CONCLUSION

Gestational diabetes is associated with increased AF insulin at 14-20 weeks, suggesting augmentation of fetal insulin production in the early fetal period in at least some cases of gestational diabetes.

Fryns syndrome: a new definition

Fryns syndrome is a lethal, autosomal recessive syndrome of multiple congenital anomalies described by Fitch et al. in 1978 and Fryns et al. in 1979. As originally described, the major diagnostic criteria included abnormal facies; small thorax with widely spaced, hypoplastic nipples; distal limb and nail hypoplasia; and diaphragmatic hernia with pulmonary hypoplasia. Malformations involving other systems occurred irregularly in published reports. We reviewed 41 published cases of Fryns syndrome and added 4 cases of our own. The major diagnostic criteria described by Fryns were consistent in all cases with the exception of two criteria. Narrow thorax with hypoplastic nipples and gastrointestinal anomalies were present in less than 50% of the cases. Although for 16 of the 41 published cases there was no information on central nervous system findings, 21 of the 29 remaining cases (72%) had CNS malformations. These lesions were absence of corpus callosum, arhinencephaly, and heterotopia of cerebral and cerebellar tissue. Similarly, for 12 of the 41 published cases there was no information on cardiovascular findings but 29 of the 33 remaining cases (88%) had congenital heart disease. These lesions were ventricular septal defects, arterial septal defects, and persistent left superior vena cava. We conclude that central nervous system anomalies and congenital heart disease should be added to the major diagnostic criteria of Fryns syndrome.

Metabolic changes in gestational diabetes

Normal pregnancy produces profound metabolic alterations that occur, in large part, by the conclusion of the first trimester. Although necessary to support the metabolic needs of the conceptus, the metabolic and cardiovascular changes of pregnancy are well established weeks before the metabolic needs of the fetus and placenta are fully expressed. The endocrine and metabolic characteristics of gestational diabetes, therefore, can only be understood against the backdrop of the rapidly changing conditions of normal pregnancy. Nondiabetic pregnancy produces an "accelerated starvation" in the fasting state with an earlier and more profound hypoglycemia and an increased fasting insulin. In the fed state, normal pregnancy produces a higher postprandial glycemic response despite an amplified first phase insulin response and higher plasma insulin concentrations. Both the intravenous glucose tolerance test and the steady state euglycemic clamp demonstrate that, by the second trimester, pregnancy produces peripheral and, perhaps, hepatic insulin resistance. The decreased peripheral uptake of glucose and the increased basal production of glucose in the fasting state support an increased flux of glucose to the fetus. Weight-matched obese gestational diabetic gravidae demonstrate a greater fall in fasting glucose and greater increase in ketosis compared with normal control gravidae. Obese GDM patients appear to have increased fasting insulin concentration compared with lean GDM and nondiabetic controls, whereas nonobese GDM patients do not appear to have elevated fasting insulin concentrations. Women with gestational diabetes have a greater rise in SI postpartum than controls, though the SI is the same in normal and gestational diabetic pregnancy in the third trimester.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal diagnosis of familial neonatal hyperinsulinemia

A kindred with familial neonatal hyperinsulinemia is described. Infant A was macrosomatic and stillborn. Infant B was macrosomatic at birth following a pregnancy uncomplicated by maternal diabetes. Following diagnosis of hyperinsulinemic hypoglycemia, this patient was treated with oral diazoxide. Therapy continued until hyperinsulinemia resolved by two years of age. Based on this history, the pregnancy with infant C was intensively monitored using ultrasonography and amniocentesis. Insulin and C-peptide concentrations in amniotic fluid were markedly increased compared to control pregnancies. Based on these results, infant C was delivered immediately upon obtaining evidence of lung maturation. Neonatal hyperinsulinemia was confirmed by a markedly increased cord plasma insulin concentration. Based on our experience, we recommend that insulin concentrations in amniotic fluid be used as an indicator of fetal hyperinsulinemia in kindreds with prior newborn hyperinsulinemic hypoglycemia. This information may be used to direct timing of delivery and therapy in the immediate postnatal period.

Rapid determination of cholesterol in single and multicomponent prepared foods

A rapid method has been developed for cholesterol determination in single and multicomponent foods. The method involves alcoholic KOH saponification of the samples, extraction of the nonsaponifiable fraction with hexane, and injection of concentrated extract into the gas chromatograph without derivatizations. It has been applied to a wide variety of frozen and refrigerated foods. More than 300 samples were analyzed with a coefficient of variation (CV) ranging from 0.5 to 8.6%. The average recoveries of cholesterol from spiked oil and tomato vegetable soup samples were 100 +/- 1.5% and 99.7 +/- 1.6% and the CVs were 1.5 and 1.6%, respectively. This method reduces labor by > 70%, eliminates dangerous chemicals, and minimizes solvent use, compared to the AOAC method and other methods cited in the manuscript. The method was used successfully on a wide variety of multicomponent foods. We recommend this method for collaborative study under the AOAC guidelines for method approval.

Gestational diabetes: predictors of subsequent disordered glucose metabolism

OBJECTIVE

We tested the hypothesis that the development of abnormal glucose metabolism after gestational diabetes can be predicted readily by means of available clinical variables.

STUDY DESIGN

Three hundred fifty nonpregnant former gestational diabetic women delivered during the previous 10 years underwent glucose tolerance tests. Variables including body mass index before the index pregnancy, pregnancy glucose tolerance test values, gestational diabetes treatment, complications, gestational age at diagnosis of gestational diabetes, and time elapsed since pregnancy were analyzed with logistic regression.

RESULTS

Variables that distinguished subjects who later developed diabetes or impaired glucose tolerance included prepregnancy body mass index (28.5 +/- 7 versus 25 +/- 5 kg/m2, p < 0.001) and fasting glucose on the pregnant oral glucose tolerance test (109 +/- 20 vs 92 +/- 15 mg/dl, p < 0.001). Logistic results with these two variables plus time since the index pregnancy predict subsequent glucose tolerance test abnormality by the following equation: estimated risk = 1/[1 + e-(-10.37 + 0.04 (fasting plasma glucose) + 0.08 (body mass index) + 0.03 (months since delivery))].

CONCLUSION

The risk for subsequent glucose abnormality among individuals with previous gestational diabetes is quantifiable based on prepregnant body mass index and fasting plasma glucose during pregnancy.

Cardiovascular response to maximal cycle exercise during pregnancy and at two and seven months post partum

We examined the cardiovascular response at rest and during upright cycle exercise in nine women during pregnancy (25.6 +/- 3.0 weeks' gestation) and at 2 months (8.8 +/- 1.8 weeks) and 7 months (30.0 +/- 2.5 weeks) post partum. Antepartum resting cardiac output, heart rate, and stroke volume were higher, whereas the arterial-venous oxygen difference was lower than both postpartum values. The antepartum resting oxygen uptake did not differ from 2 months post partum but was higher than at 7 months post partum. Cardiac output during submaximal exercise was greater antepartum than at both postpartum tests. Submaximal antepartum oxygen uptake, heart rate, and stroke volume were generally higher, and the arterial-venous oxygen difference was lower than at 7 months post partum. The slope of the antepartum cardiac output versus oxygen uptake relationship did not differ from the value at 2 months post partum, (6.16 +/- 1.38 and 5.84 +/- 1.34, p greater than 0.05) but was higher than at 7 months post partum (5.22 +/- 0.78, p less than 0.05). There were no significant differences in maximal oxygen uptake or heart rate among the three testing periods. Maximal cardiac output and stroke volume were higher antepartum than at 2 and 7 months post partum, whereas the arterial-venous oxygen difference was lower than at 7 months post partum. There were few significant differences in resting, submaximal, or maximal measurements between the two postpartum conditions. These data suggest that the augmented cardiac response to exercise during pregnancy is reduced by 2 months post partum but that additional time may be required for a complete resolution of the cardiovascular changes induced by pregnancy.

Effect of maternal weight gain during pregnancy on exercise performance

We examined the effect of maternal weight gain during pregnancy on exercise performance. Ten women performed submaximal cycle (up to 60 W) and treadmill (4 km/h, up to 10% grade) exercise tests at 34 +/- 1.5 (SD) wk gestation and 7.6 +/- 1.7 wk postpartum. Postpartum subjects wearing weighted belts designed to equal their body weight during the antepartum tests performed two additional treadmill tests. Absolute O2 uptake (VO2) at the same work load was higher during pregnancy than postpartum during cycle (1.04 +/- 0.08 vs. 0.95 +/- 0.09 l/min, P = 0.014), treadmill (1.45 +/- 0.19 vs. 1.27 +/- 0.20 l/min, P = 0.0002), and weighted treadmill (1.45 +/ 0.19 vs. 1.36 +/- 0.20 l/min, P = 0.04) exercise. None of these differences remained, however, when VO2 was expressed per kilogram of body weight. Maximal VO2 (VO2max) estimated from the individual heart rate-VO2 curves was the same during and after pregnancy during cycling (1.96 +/- 0.37 to 1.98 +/- 0.39 l/min), whereas estimated VO2max increased postpartum during treadmill (2.04 +/- 0.38 to 2.21 +/- 0.36 l/min, P = 0.03) and weighted treadmill (2.04 +/- 0.38 to 2.19 +/- 0.38 l/min, P = 0.03) exercise. We conclude that increased body weight during pregnancy compared with the postpartum period accounts for 75% of the increased VO2 during submaximal weight-bearing exertion in pregnancy and contributes to reduced exercise capacity. The postpartum increase in estimated VO2max during weight-bearing exercise is the result of consistently higher antepartum heart rates during all submaximal work loads.

Aerobic exercise during pregnancy. Special considerations

Alterations in maternal physiology during pregnancy affect the physiological respect to aerobic exercise. Maternal resting oxygen consumption (VO2) and cardiac output increase during pregnancy. Heart rate (HR) becomes progressively elevated through gestation, whereas stroke volume (SV) increases until the third trimester and then declines until term, probably because of diminished venous return. Plasma volume increases earlier and to a greater magnitude than red cell volume, resulting in the 'haemodilutional anaemia' of pregnancy and a decline in the oxygen-carrying capacity. Ventilation is greater during pregnancy because of elevated tidal volume and unchanged rate of breathing. The acute and chronic (training) responses to aerobic exercise during pregnancy have not been thoroughly investigated. Specifically, the effect of gestational age, maternal activity status, and type, duration and intensity of exercise on maternal cardiovascular response have only recently begun to be explored. During pregnancy cardiac output during submaximal exertion increases above values in non-pregnant women, except perhaps late in gestation. Both heart rate and stroke volume contribute to the elevated cardiac output. Changes in submaximal exercise VO2 during pregnancy are dependent on the mode of exercise. At the same workload, VO2 increases during weight-bearing exercise, but usually does not differ from postpartum values during weight-supported exercise. One study found no change in VO2max during pregnancy compared to postpartum values. Some recent evidence indicates that the cardiac output vs VO2 relationship for pregnant women is within the range of average values reported for non-pregnant individuals. Exercise arterial-venous oxygen difference is lower during pregnancy, suggesting that the higher cardiac output is distributed to non-exercising vascular beds. The data are limited but suggest that the perfusion of exercising muscle is unchanged during pregnancy and that the major haemodynamic change is an augmented cardiac output so that blood flow to the uterus and fetus is not compromised. Only one study has measured blood flow during exercise in pregnant women. The reported 25% decrease in uterine blood flow during supine cycle exercise in women late in gestation must be interpreted cautiously because the uterus may obstruct the vena cava in the supine position. Studies of exercising pregnant animals usually indicate a decreased uterine blood flow but an enhanced oxygen extraction; the lower blood flow may be limited to non-placental areas. The applicability of these results to humans is unknown.(ABSTRACT TRUNCATED AT 400 WORDS)

Maternal age and screening for gestational diabetes: a population-based study

The American College of Obstetricians and Gynecologists (ACOG) has recommended screening for gestational diabetes, using a 50-g, 1-hour glucose challenge (threshold for further testing 140 mg/dL or higher), for all pregnant women aged 30 or older and for younger women with risk factors. In order to assess these recommendations, we collected demographic and historic data on 6214 pregnant women representing a population of universally screened individuals. Of 125 cases of gestational diabetes diagnosed (ACOG criteria), 70 patients (56%) were under the age of 30. In addition, 44% of gestational diabetics had no risk factors. The cost per case diagnosed would be $190 with the ACOG recommendations, $192 if the age for routine screening were lowered to 25 years or more, and $222 if universal screening were practiced. Using the ACOG recommendations, 35% of gestational diabetes would go undiagnosed, with little cost savings.

Cardiovascular response to cycle exercise during and after pregnancy

Our purpose was to determine if pregnancy alters the cardiovascular response to exercise. Thirty-nine women [29 +/- 4 (SD) yr], performed submaximal and maximal exercise cycle ergometry during pregnancy (antepartum, AP, 26 +/- 3 wk of gestation) and postpartum (PP, 8 +/- 2 wk). Neither maximal O2 uptake (VO2max) nor maximal heart rate (HR) was different AP and PP (VO2 = 1.91 +/- 0.32 and 1.83 +/- 0.31 l/min; HR = 182 +/- 8 and 184 +/- 7 beats/min, P greater than 0.05 for both). Cardiac output (Q, acetylene rebreathing technique) averaged 2.2 to 2.8 l/min higher AP (P less than 0.01) at rest and at each exercise work load. Increases in both HR and stroke volume (SV) contributed to the elevated Q at the lower exercise work loads, whereas an increased SV was primarily responsible for the higher Q at higher levels. The slope of the Q vs. VO2 relationship was not different AP and PP (6.15 +/- 1.32 and 6.18 +/- 1.34 l/min Q/l/min VO2, P greater than 0.05). In contrast, the arteriovenous O2 difference (a-vO2 difference) was lower at each exercise work load AP, suggesting that the higher Q AP was distributed to nonexercising vascular beds. We conclude that Q is greater and a-vO2 difference is less at all levels of exercise in pregnant subjects than in the same women postpartum but that the coupling of the increase in Q to the increase in systemic O2 demand (VO2) is not different.(ABSTRACT TRUNCATED AT 250 WORDS)

Postpartum testing for antecedent gestational diabetes

Gestational diabetes is a predictor of glucose intolerance in subsequent pregnancies and in the nongravid state. Many pregnant women are not tested for gestational diabetes, although they or their offspring may show signs suggestive of antecedent hyperglycemia. We examined the diagnostic utility of a postpartum (within 48 hours), 100 gm, oral glucose tolerance test and cord plasma glucose, cord plasma C-peptide, and 2-hour neonatal plasma glucose tests to detect antecedent gestational diabetes in women with documented gestational diabetes (n = 37) or with normal glucose tolerance test results late in the third trimester (n = 28). The 1-hour, 2-hour, and incremental 1-hour + 2-hour [( 1-hour - fasting] + [2-hour - fasting]) [2-hour - fasting]) glucose values of the postpartum glucose tolerance test showed significant differences between study participants with and without gestational diabetes (164 +/- 30 versus 115 +/- 22, 145 +/- 31 versus 101 +/- 21, and 153 +/- 51 versus 67 +/- 33 mg/dl, respectively, p less than 0.025). Maternal fasting and 3-hour postpartum glucose tolerance test glucose, cord plasma glucose, cord plasma C-peptide, and 2-hour neonatal plasma glucose values showed no significant between-group differences. Receiver operating characteristic curve analyses for these tests indicated that the incremental 1-hour + 2-hour postpartum glucose tolerance test glucose values best sustain test specificity at the low test threshold values necessary for high test sensitivity. A threshold of 110 mg/dl for this test yielded a predicted specificity of 90% and sensitivity of 80% with regard to antecedent gestational diabetes.

Prediction of VO2max during cycle exercise in pregnant women

We measured maximal O2 uptake (VO2max) during stationary cycling in 40 pregnant women [aged 29.2 +/- 3.9 (SD) yr, gestational age 25.9 +/- 3.3 wk]. Data from 30 of these women were used to develop an equation to predict the percent VO2max from submaximal heart rates. This equation and the submaximal VO2 were used to predict VO2max in the remaining 10 women. The accuracy of VO2max values estimated by this procedure was compared with values predicted by two popular methods: the Astrand nomogram and the VO2 vs. heart rate (VO2-HR) curve. VO2max values estimated by the derived equation method in the 10 validation subjects were only 3.7 +/- 12.2% higher than actual values (P greater than 0.05). The Astrand method overestimated VO2max by 9.0 +/- 19.4% (P greater than 0.05), whereas the VO2-HR curve method underestimated VO2max by only 1.6 +/- 10.3% in the same 10 subjects (P greater than 0.05). Both the Astrand and the VO2-HR curve methods correlated well with the actual values when all 40 subjects were considered (r = 0.77 and 0.85, respectively), but the VO2-HR curve method had a lower SE of prediction than the Astrand method (8.7 vs. 10.4%). In a comparison group of 10 nonpregnant sedentary women (29.9 +/- 4.5 yr), an equation relating %VO2max to HR nearly identical to that obtained in the pregnant women was found, suggesting that pregnancy does not alter this relationship. We conclude that extrapolating the VO2-HR curve to an estimated maximal HR is the most accurate method of predicting VO2max in pregnant women.

Fetal heart rate response to maternal exertion

Doppler monitoring of fetal heart rates during maternal exertion has suggested that fetal bradycardia occurs frequently during vigorous exercise, causing concern for fetal safety. Doppler determination of fetal heart rate during vigorous maternal effort is difficult. To avoid motion artifact, we observed fetal heart rate using two-dimensional ultrasound and determined the incidence of fetal bradycardia in 45 pregnant women (age, 29.0 +/- 3.7 years [mean +/- SD]; gestational age, 25.2 +/- 3.0 weeks) during 85 submaximal and 79 maximal cycle ergometer tests. Average fetal heart rate did not change during exercise. A single episode of fetal bradycardia (heart rate less than 110 beats per minute for greater than or equal to 10 s) occurred during submaximal exertion during a maternal vasovagal episode. Sixteen episodes of fetal bradycardia were noted within three minutes after cessation of exercise, 15 of which followed maximal maternal effort. We conclude that brief submaximal maternal exercise up to approximately 70% of maximal aerobic power (maternal heart rate less than or equal to 148 beats per minute) does not affect fetal heart rate. In contrast to submaximal maternal exertion, maximal exertion is commonly followed by fetal bradycardia. This may indicate inadequate fetal gas exchange.

The "breakfast tolerance test": screening for gestational diabetes with a standardized mixed nutrient meal

In a group of 50 presumed normal pregnant women and 20 known gestational diabetic women, all in the early third trimester, the function of a standard 50 gm, 1-hour screening test for gestational diabetes was compared with that of a plasma glucose level determined 1 hour after the ingestion of a standard 600 kcal mixed nutrient breakfast (breakfast tolerance test). The mean plus 2 SD for the breakfast tolerance test was 120 mg/dl. If this were used as the threshold for a screening test, 75% of cases of gestational diabetes would be identified (sensitivity), while 94% of normal pregnant women would be excluded (specificity). A threshold of 100 mg/dl yields a sensitivity of 96% and a specificity of 74%. These results are compared with those for the standard 50 gm glucose challenge.

Practice environment is associated with obstetric decision making regarding abnormal labor

Nonmedical factors affecting obstetric decisions regarding abnormal labor were investigated in Maine, a rural state. Obstetricians were questioned about practice structure, hospital services, anesthesia support, and legal liability. Cesarean section rates specific for abnormal labor, based on hospital discharge summaries in the previous two years, correlated inversely with improved night coverage support, 24-hour blood bank availability, and more adequate anesthesia services. Neither the payment differential between vaginal and cesarean delivery nor previous legal liability were associated with increased cesarean rates for abnormal labor. We conclude that improved ancillary services may lead to lower dystocia-specific cesarean section rates.

The Apgar score revisited: influence of gestational age

We tested the hypothesis that Apgar scores are in part related to the newborn infant's level of maturity. Seventy-three pregnant women with normal fetuses of gestational age 22 to 42 weeks were studied. Fetal well-being was documented by a prospectively designed recording of pregnancy history, labor complications, and birth outcome, including cord blood pH and base deficit measurements. The 1- and 5-minute Apgar scores were directly related to gestational age. Respiratory efforts, muscle tone, and reflex were the major determinants for a decreasing Apgar score with declining gestational age. We conclude that the 1- and 5-minute Apgar scores are influenced by the infant's level of maturity and that our data may be useful in evaluating the true value of Apgar scores in assessing the fetal and neonatal condition of low birth weight infants.

Should the fifty-gram, one-hour plasma glucose screening test for gestational diabetes be administered in the fasting or fed state?

To determine whether the 50 gm, 1-hour plasma glucose screening test for gestational diabetes should be administered in the fasted or fed state, 50 presumed normal and 20 gestational diabetic pregnant women in the early third trimester underwent this test twice, once under each condition, within a 1-week interval. There was no difference in test results under the two conditions among the normal individuals (fasted 118.4 +/- 24.7 mg/dl; fed 115.8 +/- 23.4 mg/dl). However, when the test was administered to women with known gestational diabetes, the result was significantly (p = 0.011) higher if patients were fasted (173.9 +/- 28.8 mg/dl) than if they had been given a standard 600 kcal meal 1 hour previously (154.8 +/- 24.1 mg/dl). The effect of these two conditions on the sensitivity and specificity of the screening test is described, and it is suggested that the threshold for glucose tolerance testing be 130 mg/dl if the test is administered in the fed state.

Midtrimester diagnosis of severe deforming osteogenesis imperfecta with autosomal dominant inheritance

Sonographic examination of a fetus whose father had severe deforming osteogenesis imperfecta (OI) was performed. The father had multiple congenital rib and extremity fractures. Subsequent fracture and deformity had suggested an autosomal recessive OI syndrome. However, fetal sonography at 18 weeks gestational age showed foreshortening of long bones in both legs and a reduced thoracic circumference, recapitulating, in part, the father's phenotype. This third reported case of early fetal diagnosis of autosomal dominant OI suggests that the fetal sonographic phenotype reflects that of the affected parent. Implications of this case for the application of fetal sonography in dominant OI syndromes are discussed.

Neonatal morbidities in infants of mothers with glucose intolerance in pregnancy

Of 1839 pregnant women screened prospectively, 52 were identified to have glucose intolerance. Ten additional pregnant women identified as having glucose intolerance before the universal screening were also included in the study cohort. These 62 patients were followed in a perinatal high-risk clinic with weekly plasma glucose determinations. The patients were treated with diet and, in addition, 21 of 62 were treated with insulin therapeutically. By observational cohort design, the infants and a comparable number of matched controls were evaluated for evidence of neonatal morbidities and classified into percentile for birth weight. Compared with the control group, the operative mode of delivery, the mean birth weight, the birth-weight percentile, the male/female ratio, the frequency of low Apgar score (less than or equal to 6 at 1 min), and the number of infants with congenital anomalies were significantly higher in the infants born to the glucose-intolerant mothers. Although the mean maternal blood sugar was maintained within a reasonably euglycemic range, the usual neonatal morbidities were not eliminated entirely. Further understanding and management of glucose intolerance in pregnancy is necessary to further diminish or eliminate neonatal morbidities.

Perinatal management of ventral wall defects

Reported is the analysis of morbidity, mortality, and mode of delivery in 38 cases of ventral wall defects identified from among 128,500 consecutive live births in Maine (January 1975 to December 1982). Thirteen of the ventral wall defects were classified as gastroschisis, and only one had an additional defect not directly attributable to the ventral wall defect itself. By contrast, 16 of the 25 omphalocele cases had additional defects, including eight congenital heart lesions, four genitourinary malformations, two neural tube defects, and three trisomies. Ten cases of omphalocele and one of gastroschisis died, all as a result of independent defects or involvement of adjacent structures. Intrauterine growth retardation was prominently associated with gastroschisis. Vaginal delivery occurred in three of the six ventral wall defects diagnosed antenatally and in 28 of the 32 ventral wall defects not diagnosed until delivery. The only episode of birth trauma to ventral wall defect sac or abdominal viscera occurred during cesarean section in an undiagnosed case. The present data provide a basis for prognosis and management of antenatally diagnosed ventral wall defects and suggest that these defects are not, a priori, an indication for abdominal delivery.

Criteria for screening tests for gestational diabetes

A 50 gm, 1-hour glucose screening test was given to 381 gravid women 25 years of age or older. All women with plasma glucose values greater than or equal to 130 mg/dl (119 mg/dl, whole blood) were given a 100 gm, 3-hour glucose tolerance test to diagnose gestational glucose intolerance using O'Sullivan's diagnostic criteria. On the basis of the distribution of screening test values, three diagnostic zones could be identified: a zone below 135 mg/dl plasma glucose, with less than 1% probability of diabetes; a zone above 182 mg/dl plasma glucose, with more than 95% probability of diabetes; and a central zone of uncertainty (135 to 182 mg/dl, plasma glucose), where further testing is required. These test results suggest that thresholds for further testing be lowered from 143 to 135 mg/dl of plasma glucose.