Hypoglycemia during the 100-g oral glucose tolerance test: incidence and perinatal significance

Hypoglycaemia in screening oral glucose tolerance test in pregnancy with low birth weight fetus

Maternal hypoglycemia, a condition characterized by lower than normal blood glucose levels in pregnant women, has been increasingly associated with adverse pregnancy outcomes, including low birth weight (LBW) in neonates. LBW, defined as a birth weight of less than 2500 g, can result from various factors, including maternal nutrition, health status, and metabolic conditions like hypoglycemia. Maternal hypoglycemia may affect fetal growth by altering the supply of essential nutrients and oxygen to the fetus, leading to restricted fetal development and growth. This condition poses significant risks not only during pregnancy but also for the long-term health of the child, increasing the likelihood of developmental delays, health issues, and chronic conditions later in life. Research in this area has focused on understanding the mechanisms through which maternal hypoglycemia influences fetal development, with studies suggesting that alterations in placental blood flow and nutrient transport, as well as direct effects on fetal insulin levels and metabolism, may play a role. Given the potential impact of maternal hypoglycemia on neonatal health outcomes, early detection and management are crucial to minimize risks for LBW and its associated complications. Further investigations are needed to fully elucidate the complex interactions between maternal glucose levels and fetal growth, as well as to develop targeted interventions to support the health of both mother and child. Understanding these relationships is vital for improving prenatal care and outcomes for pregnancies complicated by hypoglycemia.

Hypoglycemia in Oral Glucose Tolerance Test during Pregnancy and Risk for Type 2 Diabetes-A Five-Year Cohort Study

Objective: To evaluate the risk of progression to type 2 diabetes (T2D) following reactive hypoglycemia in 100 g oral glucose tolerance test (oGTT). Methods: A retrospective analysis of parturients with up to 5-year follow-up postpartum. Data were extracted from the computerized laboratory system of Meuhedet, an Israeli HMO and cross-linked with the Israeli National Registry of Diabetes. Included were parturients with no prior diabetesand available oGTT values during pregnancy. Reactive hypoglycemia was defined as glucose levels lower than 60 mg/dL in at least one of 3 post-glucose load values in oGTT. The cohort was divided into 3 groups: normal glucose status, reactive hypoglycemia, and GDM. Maternal characteristics, laboratory data, and progression to T2D over 5 years were compared. Univariate and survival analyses assessed the adjusted hazard ratio for T2D, stratified by obesity Results: Among 14,122 parturients, 16.8% had reactive hypoglycemia, 71% had normal glucose status, and 12.2% had GDM. Adjusted for age, obesity, and hypertension, Parturients with reactive hypoglycemia had similar T2D risk compared to normal glucose status and a lower risk compared to GDM patients, regardless of obesity status. Conclusions: Reactive hypoglycemia during oGTT does not increase the risk of progressing to T2D.

Flat maternal glucose response curve and adverse pregnancy outcome

OBJECTIVE

The significance of a flat oral glucose tolerance test (OGTT) response curve in pregnancy remains unclear. We investigated the association of a flat curve with pregnancy outcomes.

STUDY DESIGN

Retrospective cohort study. Flat OGTT curve was defined by an area under the curve below the 10th percentile. Pregnancy outcomes were compared between flat and normal curve.

RESULTS

Of the 2673 eligible women, 269 had a flat response curve. Compared with the normal-response group, the flat-curve group had a lower mean birthweight (3363 ± 547 g vs. 3459 ± 519 g, p < 0.005), higher probability of small for gestational age (SGA) (19% vs. 12%, p < 0.005, aOR = 1.75, 95% CI 1.24-2.47), and 5-min Apgar score < 7 (1.12% vs. 0.29%, p < 0.05, aOR = 3.95, 95% CI 1.01-15.5). There were no differences in obstetric or maternal outcomes.

CONCLUSIONS

Flat OGTT is associated with lower birthweight, higher rates of SGA, and low Apgar scores. Detecting this previously unrecognized risk group, could potentially reduce these complications.

Normal glucose tolerant women with low glycemia during the oral glucose tolerance test have a higher risk to deliver a low birth weight infant

Background

Data are limited on pregnancy outcomes of normal glucose tolerant (NGT) women with a low glycemic value measured during the 75g oral glucose tolerance test (OGTT). Our aim was to evaluate maternal characteristics and pregnancy outcomes of NGT women with low glycemia measured at fasting, 1-hour or 2-hour OGTT.

Methods

The Belgian Diabetes in Pregnancy-N study was a multicentric prospective cohort study with 1841 pregnant women receiving an OGTT to screen for gestational diabetes (GDM). We compared the characteristics and pregnancy outcomes in NGT women according to different groups [(<3.9mmol/L), (3.9-4.2mmol/L), (4.25-4.4mmol/L) and (>4.4mmol/L)] of lowest glycemia measured during the OGTT. Pregnancy outcomes were adjusted for confounding factors such as body mass index (BMI) and gestational weight gain.

Results

Of all NGT women, 10.7% (172) had low glycemia (<3.9 mmol/L) during the OGTT. Women in the lowest glycemic group (<3.9mmol/L) during the OGTT had compared to women in highest glycemic group (>4.4mmol/L, 29.9%, n=482), a better metabolic profile with a lower BMI, less insulin resistance and better beta-cell function. However, women in the lowest glycemic group had more often inadequate gestational weight gain [51.1% (67) vs. 29.5% (123); p<0.001]. Compared to the highest glycemia group, women in the lowest group had more often a birth weight <2.5Kg [adjusted OR 3.41, 95% CI (1.17-9.92); p=0.025].

Conclusion

Women with a glycemic value <3.9 mmol/L during the OGTT have a higher risk for a neonate with birth weight < 2.5Kg, which remained significant after adjustment for BMI and gestational weight gain.

Reactive hypoglycaemia during the OGTT after gestational diabetes mellitus: Metabolic implications and evolution

AIMS

Gestational diabetes (GDM) presents an increased cardio-metabolic risk and is diagnosed with an oral glucose tolerance test (OGTT). Reactive hypoglycaemia (RH) during the OGTT in pregnancy is associated with adverse outcomes. Although postpartum OGTT after GDM is recommended, the occurrence and implications of RH are unknown. We investigated the prevalence, metabolic implications and longitudinal evolution of RH at 6-8 weeks postpartum in women with a history of GDM.

METHODS

Between 2011 and 2021, we consecutively followed 1237 women with previous GDM undergoing an OGTT at 6-8 weeks postpartum. RH was defined as 2-h glucose <3.9 mmoL/L after the OGTT. Metabolic outcomes were compared in women with and without RH (RH+/RH-). We also included a subcohort of 191 women with data on insulin sensitivity/secretion indices (MATSUDA, HOMA-IR, insulin-adjusted-secretion ISSI-2).

RESULTS

The postpartum prevalence of RH was 12%. RH+ women had a more favourable metabolic profile including a 2-5-times lower prevalence of glucose intolerance and metabolic syndrome at 6-8 weeks postpartum compared to RH- (all p ≤ 0.034). In the subcohort, women with RH+ had higher insulin sensitivity, higher ISSI-2 and an earlier glucose peak after OGTT (p ≤ 0.049) compared to RH- women at the same time point. Insulin resistance increased and ISSI-2 decreased over the first year postpartum in both groups. These changes were associated with a 50% reduction in overall RH prevalence at 1-year postpartum. Some of the favourable profiles of RH+ persisted at 1-year postpartum, without group differences in the longitudinal metabolic changes.

CONCLUSIONS

At 6-8 weeks postpartum, RH was frequent in women after GDM and associated with a better metabolic profile including increased insulin sensitivity and higher insulin-adjusted-secretory capacity. RH might be a marker of favourable metabolic prognosis in women with a history of GDM.

Hypoglycemia during the oral glucose tolerance test in pregnancy-maternal characteristics and neonatal outcomes

OBJECTIVE

To evaluate maternal and neonatal outcomes in pregnancies complicated by hypoglycemia on 100-g oral glucose tolerance test (OGTT).

METHODS

A retrospective cohort analysis of all live-born deliveries in a single medical center during 2018 and 2019 with available OGTT results and birth outcomes. Preterm deliveries (<34 weeks), multiple pregnancies and major anomalies were excluded. Hypoglycemia during OGTT was defined as at least one glucose value below 60 mg/dl. Maternal characteristics and perinatal outcomes were compared between three groups: Hypoglycemia on OGTT, Normal OGTT and Abnormal OGTT. Univariate followed by multivariate analyses were used to control for confounders.

RESULTS

Overall, 2079 women were entered into the analysis. Of these, 216 (10.4%) had at least one hypoglycemic value, 1072 (51.6%) had normal OGTTs and 791 (38%) abnormal OGTTs. Hypoglycemia in OGTT was more prevalent in multiparous women and was associated with fetal male gender. Absolute birth weight, low birth weight and small for gestational age differed between groups; however, there was no difference between groups in overall birth weight centiles (60.1 ± 26.8 versus 63 ± 26 versus 60.9 ± 27; P > 0.05). Following adjustment of confounders, hypoglycemia was not associated with rates of low birth weight or small for gestational age (P < 0.05). There were no other differences in perinatal outcomes between groups.

CONCLUSION

Hypoglycemia in OGTT is not associated with maternal or neonatal adverse outcomes.

Low glucose at 3-hour 100 gram oral glucose tolerance test: implications for glucose control

OBJECTIVE

To assess the clinical significance of a low 180-minute glucose value in a 100 g oral glucose tolerance test (OGTT) and a single high abnormal value.

METHODS

A retrospective cohort study. The study group included women with 180-minute plasma glucose levels of ≤60 mg/dL and one abnormal value in the OGTT. The control group was comprised of women with one abnormal value in the OGTT and normal 180-minute glucose value. The primary outcome was glycemic control, defined as fasting blood glucose measurements > 90 mg/dL or post-prandial glucose values >140 mg/dL or 120 mg/dL (one-hour and two-hour post-prandial, respectively) in >30% of the measurements. Secondary outcomes were the rate of insulin treatment and the perinatal outcome consisting of birthweight, large-for-gestational-age, and polyhydramnios.

RESULTS

Three hundred and one women were included, 143 in the study group and 158 in the control group. Pre-pregnancy BMI, first trimester fasting glucose levels, previous GDM, and familial diabetes were similar for both groups. Suboptimal glycemic control was more prevalent among the women in the study group (14% vs. 5.1%, respectively, p= .01). The need for insulin treatment was similar in both groups.

CONCLUSIONS

Women with one abnormal value and a 180-minute hypoglycemia in the OGTT are at increased risk for suboptimal glycemic control.

A Low 50-gram, 1-hour Glucose Challenge Test Value Predicts Neonatal Birth Weight Less than the 10th Percentile: A Systematic Review and Meta-Analysis

OBJECTIVE

This study aimed to perform a systematic review with meta-analysis to investigate if women with a low 50-g, 1-hour glucose challenge test (GCT) value are at risk for having neonates with a birth weight less than the 10th percentile.

STUDY DESIGN

A computerized literature search was conducted to identify studies that compared outcomes of pregnant women with a low GCT value versus women with a normal GCT value during routine screening for gestational diabetes.

RESULTS

Sixteen cohort studies were included for analysis. Women with a low GCT value were noted to have a 43% increased odds of having neonates with birth weight less than the 10th percentile (odds ratio [OR]: 1.43; 95% confidence interval [CI]: 1.28-1.60) and 30% increased odds of having neonates with a birth weight less than 2,500 g (OR: 1.3; 95% CI: 1.0-1.7) when compared with women with a normal GCT value. The rates of preterm delivery, neonatal intensive care unit (NICU) admission, pregnancy-induced hypertension (PIH)/preeclampsia, respiratory distress, NICU, and Apgar scores less than 7 were similar in the two groups.

CONCLUSION

A low GCT value defined as less than 90 mg/dL identifies pregnancies at elevated risk for having neonates with a birth weight less than the 10th percentile.

Use of the 50-g glucose challenge test to predict small-for-gestational-age neonates

BACKGROUND

To determine a cutoff value for the 50-g glucose challenge test (50-g GCT) for the prediction of small-for-gestational-age (SGA) neonates.

METHODS

This retrospective cohort study was conducted among pregnant women who were screened with the 50-g GCT at Hacettepe University Hospital between 1 January 2016 and 31 March 2019. Patients with 50-g GCT values <74 mg/dL (<10th percentile) served as the study group (n = 244), while patients with 50-g GCT values between 74 to 139 mg/dL served as the control group (n = 3104). Groups were compared in terms of demographic features, clinical characteristics, and obstetric outcomes. Logistic regression analysis was used to determine independent predictors of SGA. Receiver operating characteristic curves were used to assess the performance of 50-g GCT values in predicting SGA.

RESULTS

Lower birthweight, birthweight percentile, and 5th-minute Apgar values, together with higher rates of SGA, were observed in the study group (P < .001 for all). A 50-g GCT value below the 10th percentile (odds ratio: 3.29, 95% CI: 2.31-4.69, P < .001) was a significant independent factor for SGA. A cutoff value of 89.5 mg/dL (84.9% sensitivity, 85.6% specificity) was determined for SGA.

CONCLUSIONS

Low 50-g GCT values (<89.5 mg/dL) may be an early indicator for SGA.

Association of hypoglycaemia in screening oral glucose tolerance test in pregnancy with low birth weight fetus

BACKGROUND

Gestational diabetes mellitus (GDM) is a common metabolic derangement in pregnant women. In the women identified to be at high risk of GDM, a 75 g oral glucose tolerance test (OGTT) at 24-28 wk gestation is the recommended screening test in the United Kingdom as per National Institute for Health and Care Excellence (NICE). Hypoglycaemia following the glucose load is often encountered and the implication of this finding for the pregnancy, fetus and clinical care is unclear.

AIM

To determine the prevalence of hypoglycaemia at any time during the screening OGTT and explore its association with birth weight.

METHODS

All deliveries between 2009 and 2013 at the local maternity unit of the University hospital were reviewed. Of the total number of 24,154 women without pre-existing diabetes, those who had an OGTT for GDM screening based on NICE recommended risk stratification, who had a singleton delivery and had complete clinical and demographic data for analysis, were included for this study (n = 3537). Blood samples for fasting plasma glucose (FPG), 2-hour plasma glucose (2-h PG) and HbA_1c had been obtained. Birth weight was categorised as low (≤ 2500 g), normal or Macrosomia (≥ 4500 g) and blood glucose ≤ 3.5 mmol/L was used to define hypoglycaemia. Binary logistic regression was used to determine the association of various independent factors with dichotomized variables; the differences between frequencies/proportions by χ² test and comparison between group means was by one-way ANOVA.

RESULTS

Amongst the study cohort (3537 deliveries), 96 (2.7%) women had babies with LBW (< 2500 g). Women who delivered a LBW baby had significantly lower FPG (4.3 ± 0.6 mmol/L, P = 0.001). The proportion of women who had a 2-h PG ≤ 3.5 mmol/L in the LBW cohort was significantly higher compared to the cohorts with normal and macrosomic babies (8.3% vs 2.8% vs 4.2%; P = 0.007). The factors which predicted LBW were FPG, Asian ethnicity and 2-h PG ≤ 3.5 mmol/L, whereas maternal age, 2-h PG ≥ 7.8 mmol/L and HbA_1c were not significant predictors.

CONCLUSION

A low FPG and 2-h PG ≤ 3.5 mmol/L on 75-gram OGTT are significantly associated with low birth weight in women identified as high risk for GDM. Women of ethnic backgrounds (Asians) appear to be more susceptible to this increased risk and may serve as a separate cohort in whom we should offer more intensive follow up and screening for complications. Cost implications and resources for follow up would need to be looked at in further detail to support these findings.

Hypoglycaemia on an oral glucose tolerance test in pregnancy - Is it clinically significant?

AIM

During pregnancy, some women have a low glucose level on the 75 g oral glucose tolerance test (OGTT). The implications of this are unclear and there is no guideline on how to manage these women.

METHOD

We recruited pregnant women with a glucose level <3.5 mmol/L at 1- or 2-h during a screening antenatal OGTT. These women (Group 1) underwent self-monitoring of blood glucose (SMBG) over a two-week period. We also compared Group 1's demographic and pregnancy outcomes data with women who had normal OGTT results (Group 2) and women diagnosed with gestational diabetes mellitus (GDM) (Group 3).

RESULTS

52 women were recruited. Post-hoc analysis of the SMBG results revealed 50% of women experienced 2 or more elevated fasting BGLs (>5.1 mmol/L) in a week when using the Australian Diabetes in Pregnancy Society (ADIPS) criteria. A further 8% women had elevated 2-h glucose levels (above 6.7 mmol/L). Group 1 women tended to have higher booking weight. They were less likely to have a history of macrosomia or be of East or South-East Asian ethnicity. There were no differences in pregnancy outcomes between Groups 1 and 2, but Group 1 had a higher rate of congenital abnormality (6%) than Group 3 (2%).

CONCLUSION

A large proportion of pregnant women who had a low glucose level on OGTT had elevated glucose levels on SMBG, however their pregnancy outcomes were not significantly different to women who had a normal OGTT. Currently there is not enough evidence to advocate routine SMBG and treatment for this group of women.

High maternal osteocalcin levels during pregnancy is associated with low birth weight infants: A nested case-control study in China

BACKGROUND

Low birth weight infants (LBW) are at risk of chronic diseases in later life due to the disorder of energy metabolism during pregnancy. Osteocalcin (OC) has been identified as a hormone that regulate energy metabolism. However, few studies have researched on the associations between maternal serum OC levels and low birth weight infants.

OBJECTIONS

To examine the associations between maternal serum OC concentrations and LBW.

METHODS

This was a nested case-control study involving a total of 230 pregnant women delivering LBW and 382 control pregnant women (matched for infant gender, gestational age at blood draw, region of Maternity and Child Healthcare Hospital and maternal age in 1: (1-2) ratio). One serum sample was collected from each pregnant woman at 5-35 weeks' gestation. Pregnant women were divided into 3 groups (1st, 2nd and 3rd trimester group). There were 60 and 142 and 28 pregnant women delivering LBW in the first, second and third trimester, respectively. Similarly, there were 101 and 233 and 48 controls in the first, second and third trimester, respectively. Maternal serum OC and 25(OH)D concentrations were categorized into low and high levels, the low level used as reference in analyses. Binary logistic regression model was used to compute odd radio (ORs) for LBW according to levels of maternal serum OC and 25(OH)D.

RESULTS

Compared with the subjects in low level in first trimester, LBW was two times as likely to occur among pregnancy women with high serum OC concentrations (OR = 2.04, 95%CI:1.05-3.96). After adjusted for confounding factors, a significant positive relationship still existed (adjusted ORs = 2.29, 95%CI: 1.11-4.72). In second trimester, women in high level of serum OC had nearly 1.6 times the risk of delivering LBW infants as those in the low level (OR = 1.55, 95%CI: 1.01-2.37). After adjusted for confounding factors, the ORs increased (ORs = 1.59, 95%CI:1.03-2.45). No significant associations were found between maternal serum OC levels and LBW in third trimester. In addition, there were no associations between maternal 25(OH)D concentrations and LBW during pregnancy.

CONCLUSION

High maternal serum OC levels in the first or the second trimester during pregnancy may be associated with the risk of LBW.

The Association Between Low 50 g Glucose Challenge Test Values and Adverse Pregnancy Outcomes

BACKGROUND

The implications of low values on the 50 g glucose challenge test (GCT) in pregnancy are not clearly defined. Few studies have evaluated the influence of maternal low GCT values on obstetrical outcomes. This study aimed to compare pregnancy outcomes between women with low 50 g GCT values and those with normal values.

MATERIALS AND METHODS

Women undergoing gestational diabetes mellitus screening at 24-28 weeks of gestational age between January 2010 and December 2016 were retrospectively evaluated. Women with multifetal pregnancies, prepregnancy type I or II diabetes, GCT performed before 24 or after 28 weeks of gestational age, and women undergoing multiple GCTs in the same pregnancy were excluded. Low GCT values and normal GCT values were defined as ≤85 mg/dL and 86-130 mg/dL, respectively.

RESULTS

Of 3875 screened subjects, 519 (13.4%) women were included in the low GCT group and 3356 (86.6%) in the normal GCT group. Low GCT women had a significantly higher rate of small for gestational age (SGA) infants than normal GCT women (10.8% vs. 7.9%, p = 0.02). Cesarean section and postpartum hemorrhage (PPH) were less frequent in low GCT women than in normal women (32.6% vs. 42.8%, p < 0.01 and 0.2% vs. 1.2%, p = 0.03, respectively). Low GCT women had a 1.38-fold increased risk of bearing SGA infants (95% confidence intervals: 1.01-1.88, p = 0.04).

CONCLUSIONS

Rate of SGA infants was significantly higher and cesarean delivery and PPH rates were significantly lower in women with low GCT values. Low GCT values were independently associated with an increased risk of SGA.

Hypoglycemia during oral glucose tolerance test among post-bariatric surgery pregnant patients: incidence and perinatal significance

BACKGROUND

While hypoglycemia during an oral glucose tolerance test (OGTT) has been shown to occur in a considerable portion of nonpregnant post-bariatric surgery (BS) patients, its incidence among pregnant post-BS patients evaluated for gestational diabetes has only been sparsely studied.

OBJECTIVES

We investigated OGTT results and pregnancy outcomes in pregnant women who underwent 3 types of bariatric procedures before pregnancy.

SETTING

A university hospital.

METHODS

From medical records, data were collected on glucose measurements during a 100-g, 3-hour OGTT, as well as maternal and fetal outcomes.

RESULTS

Of 119 post-BS pregnant patients included in the study, 55 underwent laparoscopic sleeve gastrectomy, 34 laparoscopic adjustable gastric banding, and 30 laparoscopic Roux-en-Y gastric bypass surgery. Hypoglycemia (<55 mg/dL) was encountered in 59 (49.6%) patients during the OGTT. Among them, the nadir plasma glucose levels occurred 2 hours after glucose ingestion in 25 (42.4%) and after 3 hours in 34 (57.6%), with a median value of 47 (44-52) mg/dL. The risk of hypoglycemia was higher among women with prior laparoscopic Roux-en-Y gastric bypass surgery (83.3%) than among those with prior laparoscopic sleeve gastrectomy (54.5%; P = .009) or laparoscopic adjustable gastric banding (11.8%; P<.0001). Time from surgery to conception was significantly shorter among women with evidence of hypoglycemia during OGTT (median 711 versus 1246 days, P = .002). Compared with patients without evidence of hypoglycemia, patients who experienced hypoglycemia had lower rates of gestational diabetes (P = .03) but higher proportions of low birth weight (P = .01) and small for gestational age infants (P = .03).

CONCLUSIONS

Because hypoglycemia is common during OGTT among post-BS parturients, other diagnostic methods should be considered in this setting. The association found between hypoglycemia and poor fetal growth warrants investigation as to whether interventions to prevent hypoglycemia will improve fetal outcome.

Effects of liraglutide on hemodynamic parameters in patients with heart failure

Glucagon-like peptide-1 analogues improve left ventricular function in patients with acute myocardial infarction. This study aimed to evaluate the effects of liraglutide on hemodynamic parameters in patients with heart failure. A total of 78 patients with heart failure were enrolled in this study between August 2014 and November 2015. Of these, 52 patients were randomized 1:1 to receive either liraglutide or placebo for 7 days. Hemodynamic measurements were made using transpulmonary thermodilution and arterial pulse contour analysis. At 7 days, the difference in change of the primary endpoint of cardiac output between the liraglutide group and control group was +1.1 1/min (95% CI +0.1 to +2.2; P < 0.001). Stroke volume was significantly higher in the liraglutide group compared with the control group (difference: +14.6 ml; P < 0.001). The difference in an increase in the left ventricular contractile index after 7 days of treatment was +210.7 mmHg/s (liraglutide versus control, 95% CI−92.1 to +501.5; P < 0.001). Liraglutide causes favorable changes in markers of inflammation and oxidative stress. Glucagon-like peptide-1 may be associated with improvement in left ventricular function in patients with heart failure. These findings need to be confirmed by larger invasive trials.

Maternal hypoglycemia on 50 g glucose challenge test: outcomes are influenced by fetal gender

OBJECTIVE

To assess the perinatal outcomes in pregnant women with maternal hypoglycemia following a second trimester oral glucose challenge test (GCT).

MATERIALS AND METHODS

This retrospective case control study consisted of 2091 pregnant women with hypoglycemia (glucose levels >88 mg/dL 1 h following a 50 g GCT in the second trimester of pregnancy) and a control group of 2091 pregnant women with a GCT result between 88 and 130 mg/dL. Perinatal and neonatal characteristics obtained from electronic medical records were compared between groups.

RESULTS

The rates of pregnancy complications were similar in both groups, with the exception of a lower incidence of polyhydramnios and a higher rate of deliveries before the 34th week of gestation in patients with hypoglycemia (0.5% vs. 1.1%, P=0.016 vs. 2.6% vs. 1.7%, P=0.033); respectively. Neonates born to mothers with hypoglycemia had significantly less birth trauma (0.3% vs. 0.9%, P=0.027) and neonatal hypoglycemia. When the data for male and female infants were analyzed separately, male infants had a 1.5-fold (95% CI: 1.05-2.18) increased chance of being small for gestational age (SGA), whereas the risk for female infants did not increase (OR: 0.79, 95% CI: 0.56-1.11).

CONCLUSION

A low maternal plasma glucose level on the GCT is associated with favorable outcomes, such as decreased rates of birth trauma and neonatal hypoglycemia. In addition, male infants have a higher risk of being SGA than female infants when maternal GCT results were <88 mg/dL.

Association between low blood glucose increase during glucose tolerance tests in pregnancy and impaired fetal growth

OBJECTIVE

To evaluate how different levels of increase in maternal blood glucose from a fasting state to 2 h after an oral glucose challenge in late pregnancy are associated with fetal growth, with special emphasis on those with a low increase.

DESIGN

Prospective cohort study.

SUBJECTS

We followed 855 women, of whom 70% had an increased risk for carrying lighter babies.

STUDY DESIGN AND METHODS

Ultrasound was used to estimate fetal growth in gestational weeks 25, 33 and 37. In week 37 the women had a 75-g oral glucose tolerance test, and fasting and 2-h capillary glucose values were recorded with the difference between these two called delta (∆) glucose. Three groups were constructed from the ∆ glucose distribution: Low below the 10th centile; Medium between the 10th and 90th centiles; and High above the 90th centile. Missing data were imputed. Linear and Poisson regression models were applied.

OUTCOME MEASURES

Estimated fetal weight, percent deviation from expected fetal weight and anthropometric measures at birth.

RESULTS

The Low group carried the lightest fetuses and the High group the heaviest. The fetal growth in the Low group deviated increasingly more in a negative direction from week 25 to 37 than in the other groups.

CONCLUSION

In a high-risk population, a positive relation between ∆ glucose and fetal growth was found. The Low group demonstrated impaired growth. More attention should be paid to pregnant women with an insufficient increase in glucose after a glucose challenge. Future studies should challenge our findings in high-risk and low-risk populations.

The obstetric and neonatal implications of a low value on the 50-g glucose screening test

OBJECTIVE

To assess the relationship between a low 50-g 1-hour glucose loading test (GLT) and maternal and neonatal outcomes in women without diabetes.

STUDY DESIGN

This was a secondary analysis of a multicenter observational cohort from a randomized trial of treatment for mild gestational diabetes. Maternal and neonatal outcomes were compared between women with GLT values < 90 mg/dL and those with results 90 to 119 mg/dL.

RESULTS

Of 436 enrolled women, 297 (68.1%) had a GLT result of 90 to 119 mg/dL and 139 (31.9%) had a result of < 90 mg/dL. There was a lower incidence of neonatal hypoglycemia in those with a GLT < 90 mg/dL (5.7% versus 16.5%, p = 0.006). Other outcomes were not associated with test results.

CONCLUSION

A GLT result < 90 mg/dL compared with 90 to 119 mg/dL is associated with a lower risk of neonatal hypoglycemia, but no other significant findings.

Does hypoglycemia following a glucose challenge test identify a high risk pregnancy?

Objective

An association between maternal hypoglycemia during pregnancy with fetal growth restriction and overall perinatal mortality has been reported. In a retrospective pilot study we found that hypoglycemia was linked with a greater number of special care/neonatal intensive care unit admissions and approached significance in the number of women who developed preeclampsia. That study was limited by its retrospective design, a narrow patient population and the inability to perform multivariate analysis because of the limitations in the data points collected. This study was undertaken to compare the perinatal outcome in pregnancies with hyoglycemia following a glucose challenge test (GCT) to pregnancies with a normal GCT.

Methods

Obstetric patients (not pre-gestational diabetics or gestational diabetes before 24 weeks were eligible. Women with a 1 hour glucose ≤ 88 mg/dL (4.8 m/mol) following a 50-gram oral GCT were matched with the next patient with a 1 hour glucose of 89–139 mg/dL. Pregnancy outcomes were evaluated.

Results

Over 22 months, 436 hypoglycemic patients and 434 normal subjects were identified. Hypoglycemia was increased in women < 25 (p = 0.003) and with pre-existing medical conditions (p < 0.001). Hypoglycemia was decreased if pre-pregnancy BMI ≥ 30 (p = 0.008).

Preeclampsia/eclampsia was more common in hypoglycemic women. (OR = 3.13, 95% CI 1.51 – 6.51, p = 0.002) but not other intrapartum and perinatal outcomes.

Conclusion

Hypoglycemic patients are younger, have reduced pre-pregnancy weight, lower BMIs, and are more likely to develop preeclampsia than normoglycemic women.

The thrifty phenotype as an adaptive maternal effect

Human diseases in adulthood are increasingly associated with growth patterns in early life, implicating early-life nutrition as the underlying mechanism. The thrifty phenotype hypothesis proposed that early-life metabolic adaptations promote survival, with the developing organism responding to cues of environmental quality by selecting an appropriate trajectory of growth. Recently, some authors have proposed that the thrifty phenotype is also adaptive in the longer-term, by preparing the organism for its likely adult environment. However, windows of plasticity close early during human development, and subsequent environmental changes may result in the selected trajectory becoming inappropriate, leading to adverse effects on health. This paradox generates uncertainty as to whether the thrifty phenotype is indeed adaptive for the offspring in humans. The thrifty phenotype should not be considered a dichotomous concept, rather it refers to the capacity of all offspring to respond to environmental information during early ontogenetic development. This article argues that the thrifty phenotype is the consequence of three different adaptive processes - niche construction, maternal effects, and developmental plasticity - all of which in humans are influenced by our large brains. While developmental plasticity represents an adaptation by the offspring, both niche construction and parental effects are subject to selection on parental rather than offspring fitness. The three processes also operate at different paces. Human offspring do not become net calories-producers until around 18 years of age, such that the high energy costs of the human brain are paid primarily by the mother, even after weaning. The evolutionary expansion of human brain volume occurred in environments characterised by high volatility, inducing strong selective pressure on maternal capacity to provision multiple offspring simultaneously. The thrifty phenotype is therefore best considered as a manipulation of offspring phenotype for the benefit of maternal fitness. The information that enters offspring phenotype during early development does not predict the likely future environment of the offspring, but rather reflects the mother's own developmental experience and the quality of the environment during her own maturation. Offspring growth trajectory thus becomes aligned with long-term maternal capacity to provision. In contemporary populations, the sensitivity of offspring development to maternal phenotype exposes the offspring to adverse effects, through four distinct pathways. The offspring may be exposed to (1) poor maternal metabolic control (e.g. gestational diabetes), (2) maternally derived toxins (e.g. maternal smoking), or (3) low maternal social status (e.g. small size). Adverse consequences of these effects may then be exacerbated by (4) exposure either to the "toxic" western environment in postnatal life, in which diet and physical activity levels are mismatched with metabolic experience in utero, or at the other extreme to famine. The rapid emergence of the epidemic of the metabolic syndrome in the 20th Century reflects the rapid acceleration in the pace of niche construction relative to the slower physiological combination of developmental plasticity and parental effects.