Placental hormones and maternal glucose metabolism. A study of fetal growth in normal pregnancy

Relationship between gestational fasting plasma glucose and neonatal birth weight, prenatal blood pressure and dystocia in pregnant Chinese women

BACKGROUND

Little is known about the optimal cut-off point of fasting plasma glucose for the diagnosis of gestational diabetes mellitus for pregnant Chinese women. This study investigates the relationship between gestational fasting plasma glucose and several variables: neonatal birth weight, prenatal blood pressure and dystocia rate of pregnant women. In this study, we hoped to provide a useful tool to screen gestational diabetes mellitus in pregnant Chinese women.

METHODS

For 1058 pregnant women enrolled in our hospital at pregnancy weeks 22-30, fasting plasma glucose, neonatal birth weight and prenatal blood pressure, as well as dystocia conditions, were examined. We analysed the correlations between the following: gestational fasting plasma glucose and neonatal birth weight; prenatal blood pressure and gestational fasting plasma glucose as well as dystocia rate and gestational fasting plasma glucose group.

RESULTS

A modest correlation was observed between gestational fasting plasma glucose and neonatal birth weight (r = 0.093, p = 0.003). The macrosomia rate was smallest when the gestational fasting plasma glucose was in the range 3.51-5.5 mmol/L. Prenatal blood pressure increased linearly with increasing gestational fasting plasma glucose (p = 0.000). There was a significant difference between the dystocia rates in different fasting plasma glucose groups (chi-squared = 13.015, p = 0.043). The results showed that the dystocia rate significantly increased when gestational fasting plasma glucose was >4.9 mmol/L; p = 0.03, OR = 2.156 (95% CI, 1.077-4.318).

CONCLUSION

We suggest that the optimal range of gestational fasting plasma glucose for pregnant Chinese women is in the range 3.5-4.9 mmol/L.

2-Hour postload serum glucose levels and maternal blood pressure as independent predictors of birth weight in "appropriate for gestational age" neonates in healthy nondiabetic pregnancies

INTRODUCTION

Increased neonatal birth weight (NBW), often associated with diabetic pregnancies, is a recognized indicator of childhood obesity and future metabolic risk. Predictors of NBW in healthy non-diabetic pregnancies are not yet established. Here, we investigated the association of maternal parameters of healthy non-diabetic mothers with NBW of their "appropriate-for-gestational age" neonates.

METHODS

The study involved 36 healthy mother/infant pairs. Examined parameters included NBW, maternal age, first and last trimester (BMI), weight gain, fasting serum lipids and glucose, 2-hour postload glucose levels and blood pressure.

RESULTS

Postload-glucose levels were significantly higher in mothers of heavier neonates. ANOVA results indicated that 15% increase in postload-glucose levels corresponded to more than 0.5 Kg increase in NBW in the third tertile. NBW correlated positively with postload glucose levels, and negatively with systolic blood pressure. Regression analysis showed that the main predictors of NBW were postload-glucose levels (B = 0.455, P = 0.003), followed by systolic blood pressure (B = -0.447, P = 0.004), together predicting 31.7% NBW variation.

CONCLUSION

This study highlights that increased maternal postload sugar levels and blood pressure, within the normal range, highly predicts NBW of healthy mothers. These findings may provide focus for early dietary intervention measures to avoid future risks to the mother and baby.

Maternal mid-upper arm circumference is associated with birth weight among HIV-infected Malawians

The authors examined the relationship of maternal anthropometry to fetal growth and birth weight among 1005 human immunodeficiency virus (HIV)-infected women in Lilongwe, Malawi, who consented to enrollment in the Breastfeeding, Antiretrovirals, and Nutrition Study (www.thebanstudy.org). Anthropometric assessments of mid-upper arm circumference (MUAC), arm muscle area (AMA), and arm fat area (AFA) were collected at the baseline visit between 12 and 30 weeks' gestation and in up to 4 follow-up prenatal visits. In longitudinal analysis, fundal height increased monotonically at an estimated rate of 0.92 cm/wk and was positively and negatively associated with AMA and AFA, respectively. These latter relationships varied over weeks of follow-up. Baseline MUAC, AMA, and AFA were positively associated with birth weight (MUAC: 31.84 g/cm(2), 95% confidence interval [CI], 22.18-41.49 [P < .01]; AMA: 6.88 g/cm(2), 95% CI, 2.51-11.26 [P < .01]; AFA: 6.97 g/cm(2), 95% CI, 3.53-10.41 [P < .01]). In addition, MUAC and AMA were both associated with decreased odds for low birth weight (LBW; <2500 g) (MUAC: odds ratio [OR] = 0.85, 95% CI, 0.77-0.94 [P < .01]; AMA: OR = 0.95, 95% CI, 0.91-0.99 [P < .05]). These findings support the use of MUAC as an efficient, cost-effective screening tool for LBW in HIV-infected women, as in HIV-uninfected women.

Maternal glycemia and risk of large-for-gestational-age babies in a population-based screening

OBJECTIVE

Gestational diabetes is a risk factor for large-for-gestational-age (LGA) newborns, but many LGA babies are born to mothers with normal glucose tolerance. We aimed to clarify the association of maternal glycemia across the whole distribution with birth weight and risk of LGA births in mothers with normal glucose tolerance.

RESEARCH DESIGN AND METHODS

We undertook a population-based gestational diabetes screening in an urban area of Hungary in 2002-2005. All singleton pregnancies of mothers >or=18 years of age, without known diabetes or gestational diabetes (World Health Organization criteria) and data on a 75-g oral glucose tolerance test at 22-30 weeks of gestation, were included (n = 3,787, 78.9% of the target population). LGA was determined as birth weight greater than the 90th percentile using national sex- and gestational age-specific charts.

RESULTS

Mean +/- SD maternal age was 30 +/- 4 years, BMI was 22.6 +/- 4.0 kg/m(2), fasting blood glucose was 4.5 +/- 0.5 mmol/l, and postload glucose was 5.5 +/- 1.0 mmol/l. The mean birth weight was 3,450 +/- 476 g at 39.2 +/- 1.2 weeks of gestation. There was a U-shaped association of maternal fasting glucose with birth weight (P(curve) = 0.004) and risk of having an LGA baby (lowest values between 4 and 4.5 mmol/l, P(curve) = 0.0004) with little change after adjustments for clinical characteristics. The association of postload glucose with birth weight (P = 0.03) and the risk of an LGA baby (P = 0.09) was weaker and linear.

CONCLUSIONS

Both low and high fasting glucose values at 22-30 weeks of gestation are associated with increased risk of an LGA newborn. We suggest that the excess risk related to low glucose reflects the increased use of nutrients by LGA fetuses that also affects the mothers' fasting glucose.

Expression of placental serotonin transporter and 5-HT 2A receptor in normal and gestational diabetes mellitus pregnancies

Recent studies reveal that serotonin (5-hydroxytryptamine, 5-HT) might play a role in the aetiology of gestational diabetes mellitus (GDM). The involvement of the serotonin transporter (SERT) and 5-HT(2A) receptor (5-HT(2A)R) in diabetes has also been suggested. However, placental SERT and 5-HT(2A)R have never been studied in GDM-complicated pregnancies. The aim of this study was to investigate the effect of GDM on the expression of both placental SERT and 5-HT(2A)R. First, immunohistochemical analysis demonstrated the presence of SERT and 5-HT(2A)R proteins in the villous trophoblast and the fetal capillary endothelium of normal term placental tissue. Protein and mRNA expression of SERT and 5-HT(2A)R in the villous cytotrophoblastic and syncytiotrophoblastic cells was further confirmed in primary culture. A significantly (P < 0.05) decreased expression of SERT mRNA (56.3%) and protein (79.7%), and 5-HT(2A)R mRNA (79.1%) and protein (29.1%) was observed in placental tissues from GDM compared with non-GDM pregnancies. These data suggest that SERT and 5-HT(2A)R might be implicated in the aetiology of GDM. Moreover, the presence of SERT and 5-HT(2A)R in villous trophoblastic cells argues in favour of an important role of serotonin in human placental function.

The validity of oral glucose tolerance test after 36 weeks’ gestation

OBJECTIVE

Secretion of anti-insulin hormones plateaus near term, questioning the validity of OGTT (oral glucose tolerance test) during that period. We aimed at assessing the feasibility of OGTT near term as compared to OGTT at 26-32 weeks.

PATIENTS AND METHODS

One thousand four hundred and eighty seven pregnant women were screened by GCT (glucose challenge test), and 282 (19%) of them performed an OGTT at 26th-32nd weeks ("early" OGTT) after meeting the threshold value for GCT. Forty-one women with abnormal and 16 with normal early OGTT underwent a repeated OGTT at 36-40 weeks' gestation ("late" OGTT). Blood glucose levels during GCT and OGTT were compared between women with early and late abnormal OGTT and women who converted from early abnormal to late normal OGTT.

RESULTS

Thirty-six out of 41 participants (88%) with early abnormal OGTT had abnormal test near term as well (Group I). Five women with an early abnormal OGTT converted to normal according to a late OGTT (Group II). These women had lower glucose levels on both late and early OGTT as compared with Group I. All 16 women who tested normal on early OGTT had a consistently normal late OGTT. Glucose levels for all 57 women did not significantly differ between early and late OGTT. The sensitivity, specificity, and positive and negative predictive values of late OGTT were 88%, 100%, 100%, and 76%, respectively.

CONCLUSION

The positive predictive value of late OGTT performed at 36-40 weeks' gestation is 100%. This test may be used to detect gestational diabetes in women near term.

Chronic estradiol and progesterone treatment in conscious dogs: effects on insulin sensitivity and response to hypoglycemia

We evaluated the effect of chronic (3 wk) subcutaneous treatment with progesterone and estradiol (PE; producing serum levels observed in the 3rd trimester of pregnancy) or placebo (C) on hepatic and whole body insulin sensitivity and response to hypoglycemia in conscious, overnight-fasted nonpregnant female dogs, using tracer and arteriovenous difference techniques. Insulin was infused peripherally for 3 h at 1.8 mU x kg(-1) x min(-1). Glucose was allowed to fall to 3 mM (Hypo) or maintained at 6 mM (Eugly) by peripheral glucose infusion. Insulin concentrations were significantly higher in Eugly-PE (n = 7) and Hypo-PE (n = 7) than in Eugly-C (n = 6) and Hypo-C groups (n = 7), but there were no significant differences in hepatic insulin extraction. Concentrations of glucagon, cortisol, epinephrine, and norepinephrine did not differ significantly between Eugly groups or between Hypo groups. Whole body glucose disposal, adjusted for the differences in insulin between groups, was 35% higher in Eugly-C vs. Eugly-PE groups (P < 0.05). Eugly-C and Eugly-PE groups exhibited similar rates of net hepatic glucose uptake, but the rate of glucose appearance was greater in Eugly-PE in the last hour (P < 0.05). Net hepatic glucose output was greater (P < 0.05) in Hypo-PE than in Hypo-C groups, and the glucose infusion rate required to maintain equivalent hypoglycemia was less (P < 0.05). The rate of gluconeogenic flux did not differ between Hypo groups. Chronic progesterone and estradiol exposure caused whole body (primarily skeletal muscle) insulin resistance and enhanced the liver's response to hypoglycemia without altering counterregulatory hormone concentrations.

The principles of dietary management of gestational diabetes: reflection on current evidence

BACKGROUND

Gestational diabetes (GDM) is the commonest metabolic disorder of pregnancy. Most women with GDM are treated with nutritional management alone. There are conflicting guidelines surrounding its dietary management and this has resulted in a lack of conformity to the dietary advice currently prescribed. There is also conflicting opinions to the effectiveness of dietary management of GDM on pregnancy outcomes. The aim of this review was to examine the scientific evidence for the optimal nutritional management of GDM.

METHODS

A Medline search of all English papers published between 1995 and 2001 that cross-referenced GDM with diet was under taken. Because of the poor quality of many of these papers, literature prior to 1995 known to the authors and considered relevant to the review were also included.

RESULTS

The evidence base in this area is of poor quality. One systematic review based on randomized control trials failed to show any benefit from dietary intervention in GDM. However, that review did not include informative clinical and observational studies that are not classified as randomized controlled trials. Overall current evidence points to the effectiveness of dietary advice as a means of improving maternal hyperglycaemia and reducing the risk of accelerated foetal growth. The evidence surrounding energy restriction, carbohydrate and fat manipulation in GDM remains controversial.

CONCLUSIONS

Current but limited evidence supports dietary alterations to reduce rates of accelerated foetal growth. There is a clear need for good quality randomized control trials in this area.

Maternal glucose concentration influences fetal growth, gestation, and pregnancy complications

Using 1990-1995 data, the authors examined the influence of post-challenge maternal glucose concentration on pregnancy outcome in 1,157 nondiabetic US gravidas. After control for potential confounding variables and comparing gravidas with lower glucose concentrations (<99 mg/dl) with the others, they found that mean birth weight increased by 50 g and 200 g with glucose concentrations of 99-130 mg/dl and >130 mg/dl, respectively. Increased maternal glucose concentration also was associated with an increased risk of large-for-gestation fetuses (p for trend < 0.001) and a decreased risk of fetal growth restriction (p for trend < 0.05). The association between glucose and gestation was inverse and significantly shortened when glucose concentrations were higher. Maternal complications increased twofold or more with high glucose concentrations and included cesarean section and clinical chorioamnionitis. Chorioamnionitis in combination with high maternal glucose concentration increased the risk of very preterm delivery almost 12-fold. These observations extend Pedersen's hypothesis-that high concentrations of maternal glucose give rise to increased nutrient transfer to the fetus and increase fetal growth, beyond the model of maternal diabetes (Acta Endocrinol 1954;16:330-42). They raise the question of whether higher, but seemingly normal maternal glucose concentration predisposes to or is a marker for placental inflammation and infection.

Observational study of maternal anthropometry and fetal insulin

AIMS

To examine the relation between maternal body fat and fetal metabolism.

METHODS

In this observational study, cord blood samples were collected from 60 infants of healthy women for the measurement of insulin and C peptide concentrations. Maternal weight, height, body mass index (BMI) and body composition (skinfold thickness measurements and bioelectrical impedance) were assessed at 13-15 weeks of gestation. Twenty five of the volunteers agreed to have a 75 g oral glucose tolerance test at 28-31 weeks of gestation.

RESULTS

Positive correlations were observed with both cord insulin or C peptide concentrations and maternal early pregnancy BMI (r=0.44, p=0.002 and r=0.33, p=0.008, respectively). There was no significant correlation between cord insulin or C peptide concentrations and birthweight or birth weight centiles.

CONCLUSION

Maternal BMI could be a predictor of fetal cord insulin concentration.

The diagnosis and classification of gestational diabetes mellitus: is it time to change our tune?

OBJECTIVE

This study was designed to determine the impact on our population of adopting the Carpenter and Coustan criteria for gestational diabetes mellitus in place of the currently used National Diabetes Data Group criteria, to review the evidence supporting replacement of the National Diabetes Data Group criteria with the Carpenter and Coustan criteria, and to propose analogous diagnostic criteria for diabetes in pregnant and nonpregnant women.

STUDY DESIGN

The National Diabetes Data Group criteria and the proposed Carpenter and Coustan criteria were both used to retrospectively review medical records of patients screened for gestational diabetes mellitus during 1995 and 1996 in the Kaiser Permanente Northwest Division. Computerized search was performed on automated data systems and software was used for statistical analyses. A MEDLINE review of relevant literature was conducted.

RESULTS

Of 8857 pregnant women screened for gestational diabetes in 1995 and 1996, 284 (3.21%) met the National Diabetes Data Group criteria, whereas 438 (4.95%) met the Carpenter and Coustan criteria. We estimate that in our population use of the Carpenter and Coustan criteria in 1996 could at best have reduced the prevalence of infants weighing >/=4000 g from 17.1% to 16.9% and the prevalence of infants weighing >/=4500 g from 2.95% to 2.91%.

CONCLUSIONS

Replacing the National Diabetes Data Group criteria with the Carpenter and Coustan criteria would increase by 54% the number of pregnant women with a diagnosis of gestational diabetes mellitus and would also increase costs, while only minimally affecting prevalence of infant macrosomia. The medical literature does not provide compelling evidence for adopting the Carpenter and Coustan criteria. Standardization of both measurement of venous plasma glucose level and diagnostic criteria for gestational diabetes mellitus is an important goal. Parallel criteria for diagnosis and classification of diabetes mellitus in pregnant and nonpregnant women should be developed.