Birthweight of babies born to mothers with type 1 diabetes: is it related to blood glucose control in the first trimester?

Exploring the relationship between maternal Continuous Glucose Monitoring "time in range" and fetal abdominal circumference in pregnant women with Type 1 Diabetes

BACKGROUND

To explore the relationship between maternal glycaemic control and fetal abdominal circumference in pregnancies complicated by T1D.

METHODS

This is a retrospective cohort study of 81 pregnant women with T1D using CGM. Inclusion criteria were T1D, CGM use, ≥2 in-house ultrasounds, and the birth of a live singleton neonate between 1st December 2019 and 1st December 2022. Linear regression analysis was used to assess the cross-sectional relationships between estimated fetal abdominal circumference (AC) on ultrasound and time in range (TIR) at matched time-points in the third trimester of pregnancy. Linear regression analysis was also used to examine whether first trimester TIR and HbA1c predicts third trimester fetal AC.

RESULTS

At baseline, the mean ± standard deviation (SD) of the first trimester HbA1c was 7.0 ± 1.4% and mean ± SD total daily dose (TDD) insulin was 46.6 ± 21.0 units. The mean ± SD birthweight was 3367.0 ± 861.3 grams. There was no cross-sectional relationship between TIR and fetal AC at 28-, 32- or 36-week' gestation. The results of the regression analysis indicate a significant relationship between first trimester TIR (independent predictor) and fetal AC (dependent variable) at 32- and 36-weeks' gestation while controlling for maternal age, BMI, pump use, and TDD insulin (Adjβ= -0.42, 95%CI -0.80 to -0.03 and Adjβ = -0.57, 95%CI -1.02 to -0.12 at 32- and 36-weeks respectively). Although there was a significant relationship between first trimester HbA1c and fetal AC at 32-weeks' gestation (β = 3.81, 95%CI 0.29 to 7.33), the relationship was not significant after adjustment for confounders.

CONCLUSIONS

There was no cross-sectional relationship between TIR and fetal AC in the third trimester of pregnancy but first trimester TIR did predict fetal AC in late pregnancy.

Health care and risk of adverse pregnancy outcomes among diabetic women: an updated meta-analysis

PURPOSE

Diabetic women appear to have adverse pregnancy outcomes. Although there were two meta-analyzes that examined the association between health care and adverse pregnancy outcomes, their results were limited because they only included congenital anomaly and perinatal mortality, and they did not clarify the detailed situations of diabetes and health care. This meta-analysis aims to completely evaluate the effects of health care in improving adverse pregnancy outcomes among diabetic mothers.

METHODS

CNKI, EMBASE, Web of Science, and PubMed databases were searched for eligible studies up to December 2017, without any restrictions. Relevant cohort studies characterizing the relationship between health care and adverse pregnancy outcomes were selected for inclusion in the meta-analysis. We also screened the reference list of relevant studies. The fixed-effect models or random-effect models were used to calculate the risk estimates. The potential sources of heterogeneity were explored by stratified and sensitivity analyzes.

RESULTS

Twenty-one studies with 6685 cases were included in our analysis. Health care was associated with significantly decreased risk of congenital anomaly (RR 0.237; 95% CI 0.166-0.338), perinatal death (RR 0.457; 95% CI 0.294-0.712), large for gestational age (LGA) (RR 0.794; 95% CI 0.640-0.986), and neonatal hypoglycemia (RR 0.672; 95% CI 0.486-0.929). Publication bias was not found in most results, with the exception of congenital anomaly and small for gestational age (SGA).

CONCLUSION

Health care is associated with decreased risk of congenital anomaly, perinatal death, LGA, neonatal hypoglycemia.

Increased fat mass and cardiac septal hypertrophy in newborn infants of mothers with well-controlled diabetes during pregnancy

BACKGROUND

Improved glycaemic control during pregnancy in mothers with type 1 diabetes (T1DM) and gestational diabetes (GDM) has resulted in a marked reduction of perinatal mortality and morbidity, but the prevalence of macrosomia is usually high.

OBJECTIVE

We used non-invasive anthropometric methods to estimate the body composition and the thickness of the interventricular heart septum in 18 infants of mothers with well-controlled T1DM, 10 infants of mothers with GDM and 28 infants of healthy control mothers matched for gestational age and mode of delivery.

METHODS

Skinfold measurements were obtained with a Harpenden calliper within 48 h after delivery. Echocardiography was also performed to measure the thickness of the interventricular septum. Cord blood was sampled for assays of C-peptide, leptin and IGF-I.

RESULTS

The rates of macrosomia (gestational age-adjusted birth weight >2 standard deviation score, SDS) were 56 and 30% in infants of mothers with T1DM and GDM, respectively, compared to 10% in control infants. The body fat content was 40% (0.2 kg) higher and the interventricular heart septum thickness was increased by 20% in both groups of infants of diabetic mothers. We found no associations between maternal levels of HbA1c during pregnancy and body composition or interventricular heart septum thickness. Cord levels of C-peptide and leptin were significantly higher in infants of T1DM mothers than in control infants. Cord leptin level was associated with birth weight SDS and percent body fat in infants of T1DM mothers. IGF-I was associated with percent body fat in infants of GDM mothers and control mothers. A multiple-regression analysis showed that 50% of the variation in body weight SDS could be determined, with IGF-I, leptin and C-peptide as independent variables.

CONCLUSION

Both fat mass and cardiac septal thickness are increased in newborn infants of women with T1DM and GDM in spite of efforts to achieve good glycaemic control during pregnancy.

Fetal growth trajectories in Type-1 diabetic pregnancy

OBJECTIVE

To describe the individual intrauterine growth patterns of fetuses of insulin-dependent (Type-1) diabetic women and to examine determinants of overgrowth (macrosomia) and its timing.

METHODS

This retrospective longitudinal study examined the developmental trajectories of fetal abdominal circumference (AC) and biparietal diameter in 76 Type-1 diabetic women with singleton pregnancies. Latent class analysis was used to identify subgroups of patients with a shared fetal AC growth trajectory. Subsequently, maternal factors, including glycemic control as assessed by glycosylated hemoglobin (HbA1c), were examined to see whether they had any effect on fetal growth.

RESULTS

Four subgroups with different AC growth patterns were identified. Differences in birth weight between the distinct subgroups were related to the shape of the AC growth velocity curve over gestation. Acceleration of AC growth commencing before or after 25 weeks' gestation was associated with the birth of a heavy or large-for-dates baby in 94 and 56% of cases, respectively. Poor glycemic control (HbA1c > 7.0%) during the periconception period or before 12 weeks' gestation was a modest predictor of midtrimester growth in AC. Other diabetes-related factors, fetal sex, parity, or maternal weight/obesity were unrelated to the fetal growth pattern.

CONCLUSION

The findings suggest that an individual fetus's growth trajectory is set early in gestation and that the contemporaneous degree of maternal glycemia plays a role in determining birth weight.

Etiology, detection, and management of fetal macrosomia in pregnancies complicated by diabetes mellitus

Babies of mothers who have diabetes are more likely than babies of nondiabetic women to be large for gestational age. A greater proportion of their birth weight consists of fat mass, much of which is distributed to the trunk and abdomen. The maternal and fetal consequences of diabetic fetopathy, theories and evidence of how it develops, and management considerations relative to excessive growth of the fetus of a diabetic woman are explored in this chapter.

Maternal glycated haemoglobin, pre-gestational weight, pregnancy weight gain and risk of large-for-gestational-age babies: a Danish cohort study of 209 singleton Type 1 diabetic pregnancies

AIMS

To examine the association between maternal glycated haemoglobin in the second half of diabetic pregnancies and the relative risk of delivering large-for-gestational-age (LGA) babies, controlling for maternal body mass index (BMI) before pregnancy, weight gain, age, White class and smoking habits.

METHODS

We identified all pregnant diabetic women in North Jutland County, Denmark from 1985 to 2003. Data on HbA(1c) values from the 20th gestational week to term were collected from medical records and the babies were classified as large, normal or small for gestational age. The association between glycated haemoglobin (HbA(1c)) and relative risk of delivering an LGA baby was quantified based on logistic regression models and stratified analysis controlling for the five covariates.

RESULTS

We included 209 singleton pregnancies with assessable HbA(1c) values of which 59%[95% confidence interval (CI) 52-65%] terminated with an LGA baby. Increasing levels of HbA(1c), BMI and weight gain were all associated with increasing risk of delivering an LGA baby. Analyses stratified according to maternal BMI showed that the association between HbA(1c) and risk of delivering an LGA baby was restricted to pregnancies with pre-pregnancy BMI > 23 kg/m(2). We found no association between HbA(1c) and risk of delivering an LGA baby in pregnancies with lower BMI.

CONCLUSION

The positive association between glycated haemoglobin and birth of an LGA baby seems to be restricted to women with BMI > 23 kg/m(2).

Fetal growth patterns in fetuses of women with pregestational diabetes mellitus

OBJECTIVE

To assess the effect of glucose control on the rate of growth of fetuses in women with pregestational diabetes mellitus (Types 1 and 2).

METHODS

All pregestational diabetic women booked at Mater Mothers' Hospital, Brisbane, Australia, between 1 January 1994 and 31 December 2002, were included. Pregnancies with congenital fetal anomalies, multiple pregnancies, and pregnancies terminated prior to 20 weeks' gestation were excluded. Dating scans were performed before 14 weeks' gestation and serial scans were performed at 18, 24, 28, 32 and 36 weeks. Fetal parameters, including biparietal diameter, femur length and abdominal circumference, were recorded. The daily growth rates for biparietal diameter, femur length, and fetal abdominal area were calculated and compared with those in a low-risk (non-diabetic) population. The growth rates in fetuses of women with satisfactory diabetic control (HbA1c < 6.5%) and unsatisfactory control (HbA1c > or = 6.5%) in the three trimesters were compared.

RESULTS

A total of 174 diabetic pregnancies were included and a total of 997 ultrasound scans were performed. The growth rates for fetuses of mothers with diabetes mellitus were significantly higher than for those in the low-risk population. The z-scores for biparietal diameter, femur length, and fetal abdominal area were 0.18, 0.59 and 1.44, respectively. Fetuses of diabetic mothers with high HbA1c in the first trimester had significantly greater fetal abdominal area growth rate than those with normal HbA1c (fetal abdominal area z-score of 1.7 vs. 0.75, P = 0.009). Although the fetal abdominal area z-scores in fetuses of diabetic mothers with high HbA1c in the second or third trimesters were also higher than those with normal HbA1c levels, the differences did not reach statistical significance. Maternal obesity did not influence the fetal growth rate.

CONCLUSION

The rate of growth of fetuses of diabetic mothers differs from that of the normal population. Growth acceleration persists until the late third trimester. Moreover, periconceptional glucose control appears to have a significant effect on accelerated growth of the fetal abdominal area.

Maternal glucose levels influence birthweight and 'catch-up' and 'catch-down' growth in a large contemporary cohort

AIM

To explore the effects of maternal glucose on birthweight, infant and childhood growth in non-diabetic pregnant women using routinely collected data.

METHODS

Routinely collected data were extracted retrospectively from two clinical databases. These data comprised measurements of maternal random plasma glucose, infant birthweight, infant and child weight and height at 6-8 weeks, 24-36 weeks and 96-120 weeks in 6263 cases. After data cleaning, 4681 were analysed.

RESULTS

When the data were analysed in thirds, a positive association between birthweight standard deviation scores (SDS), weight SDS and height SDS with maternal random plasma glucose (RPG) was observed. Regression analysis of birthweight SDS and RPG was significant (P < 0.001). Babies were approximately 48 g heavier at birth for each 1 mmol/l increase of mother's RPG. Infants who showed 'catch-up' growth (as shown by change in weight SDS) at 2 years were born to mothers with lower glucose levels than infants who showed 'catch-down' growth (P < 0.001).

CONCLUSIONS

Random maternal glucose concentrations (taken at 28 weeks' gestation) in the normal range are positively related to birthweight. Glucose concentrations also predict greater weight and length in infancy. Despite this, babies born to mothers with higher glucose concentrations within the normal range show significant 'catch-down' growth in infancy as shown by a fall in weight SDS.

Exposure to maternal diabetes is associated with altered fetal growth patterns: A hypothesis regarding metabolic allocation to growth under hyperglycemic-hypoxemic conditions

The prevalence of diabetes is rising worldwide, including women who grew poorly in early life, presenting intergenerational health problems for their offspring. It is well documented that fetuses exposed to maternal diabetes during pregnancy experience both macrosomia and poor growth outcomes in birth size. Less is known about the in utero growth patterns that precede these risk factor expressions. Fetal growth patterns and the effects of clinical class and glycemic control were investigated in 37 diabetic pregnant women and their fetuses and compared to 29 nondiabetic, nonsmoking maternal/fetal pairs who were participants in a biweekly longitudinal ultrasound study with measurements of the head, limb, and trunk dimensions. White clinical class of the diabetic women was recorded (A2-FR) and glycosylated hemoglobin levels taken at the time of measurement assessed glycemic control (median 6.9%, interquartile range 5.6-9.2%). No significant difference in fetal weight was found by exposure. The exposed sample had greater abdominal circumferences from 21 weeks (P < or = 0.05) and shorter legs, but greater upper arm and thigh circumferences accompanied increasing glycemia in the second trimester. In the third trimester, exposed fetuses had a smaller slope for the occipital frontal diameter (P = 0.00) and were brachycephalic. They experienced a proximal/distal growth gradient in limb proportionality with higher humerus / femur ratios (P = 0.04) and arms relatively long by comparison with legs (P = 0.02). HbA1c levels above 7.5% accompanied shorter femur length for thigh circumference after 30 gestational weeks of age. Significant effects of diabetic clinical class and glycemic control were identified in growth rate timing. These growth patterns suggest that hypoxemic and hyperglycemic signals cross-talk with their target receptors in a developmentally regulated, hierarchical sequence. The increase in fetal fat often documented with diabetic pregnancy may reflect altered growth at the level of cell differentiation and proximate mechanisms controlling body composition. These data suggest that the maternal-fetal interchange circuit, designed to share and capture resources on the fetal side, may not have had a long evolutionary history of overabundance as a selective force, and modern health problems drive postnatal sequelae that become exacerbated by increasing longevity.

The relationship between birth weight and maternal glycated haemoglobin (HbA1c) concentration in pregnancies complicated by Type 1 diabetes

AIM

To examine the relationships between maternal HbA1c concentration at different time points and birth weight in pregnancies complicated by pre-existing Type 1 diabetes.

METHODS

A comprehensive audit dataset was collected prospectively on all deliveries in Scotland to women with pre-existing Type 1 diabetes occurring between 1 April 1998 and 31 March 1999. Data items included HbA1c concentrations prior to conception and in each of the three trimesters of pregnancy, and birth weight. Relationships between standardized birth weight and HbA1c concentrations at each of the four time points were examined using correlation analysis.

RESULTS

Standardized birth weight (Z scores) could be calculated for 203 of 208 singleton liveborn infants. HbA1c concentrations, standardized to correct for assay differences among hospitals, at different time points were available for between 134 (pre-pregnancy) and 192 (third trimester) cases. Standardized birth weight, relative to a reference population, showed a unimodal distribution, shifted to the right (mean, +1.57 sd). There was a significant negative correlation between pre-pregnancy HbA1c and birth weight (Spearman's R, -0.208; P = 0.016). There were no statistically significant correlations for other time points.

CONCLUSIONS

Standardized birth weight scores of the infants of diabetic mothers are higher than those of a reference population. There is no simple relationship between maternal glycaemic status and birth weight, but there appears to be a paradoxical inverse relationship between pre-pregnancy glycaemic control and standardized birth weight.

Fetal growth spurt and pregestational diabetic pregnancy

OBJECTIVE

To assess the timing of fetal growth spurt among pre-existing diabetic pregnancies (types 1 and 2) and its relationship with diabetic control. To correlate fetal growth acceleration with factors that might influence fetal growth.

RESEARCH DESIGN AND METHODS

This retrospective study involved all pregestational diabetic pregnancies delivered at a tertiary obstetric hospital in Australia between 1 January 1994 and 31 December 1999. Pregnancies with major congenital fetal anomalies, multiple pregnancies, small-for-gestational-age pregnancies (<10th centile), and those that were terminated before 20 weeks were excluded. In this cohort, pregnancies delivered at term had at least four ultrasound scans performed. The first scans were performed before 14 weeks of gestation and were regarded as dating scans. Abdominal circumference measurements were retrieved from the ultrasound reports. The z-scores for abdominal circumferences, according to the gestational age, were calculated. The gestations when the ultrasound scans were performed were stratified at four weekly intervals beginning at 18 weeks and continuing through the rest of the study. Majority of these diabetic pregnancies had ultrasound scans performed at 18, 28, 32, and 36 weeks. The abdominal circumference z-scores for pregnancies with large-for-gestational-age (LGA) babies (>90th centile for gestation) were compared with babies with normal birth weights.

RESULTS

A total of 101 diabetic pregnancies were included. Diabetic mothers, who had LGA babies, had significantly higher prepregnancy body weight and BMI (P < 0.05). There were no differences in maternal age or parity among the two groups. There were also no differences in the first-, second-, and third-trimester HbA(1c) levels between the two groups. The abdominal circumference z-scores were significantly higher for LGA babies from 18 weeks and thereafter. The differences increased progressively as the gestation advanced. Maximum difference was noted in the third trimester (30-38 weeks).

CONCLUSIONS

Fetal growth acceleration in LGA fetuses of diabetic mothers starts in the second trimester, from as early as 18 weeks. In this study, glucose control did not appear to have a direct effect on the incidence of LGA babies, and such observation might result from the effects of other confounding factors.

Factors affecting fetal weight distribution in women with type I diabetes

OBJECTIVE

To identify factors independently affecting fetal weight in women with type I diabetes.

DESIGN

Prospectively recorded data in consecutive women with type I diabetes, between 1975-1992.

SETTING

Simpson Memorial Maternity Hospital, Edinburgh. Population Three hundred and two pregnancies with type I diabetes identified before pregnancy, with antenatal care and delivery in the Simpson Memorial Maternity Hospital, a singleton pregnancy, and the same diabetic physician.

METHODS

Normal ranges for birthweight were established for the total hospital population. All cases and the total population had pregnancy dating by ultrasound. The relation between standardised birthweight and explanatory variables was investigated using correlation analysis, t tests and chi2 tests as appropriate, and subsequently using multiple linear regression.

RESULTS

Standardised birthweight in cases, compared with the reference population, showed a unimodal, approximately normal distribution, markedly shifted to the right (mean + 1.26 SD). The most predictive variable was glycated haemoglobin concentration at 27-33 weeks, which explained 6.3% of the birthweight variance, while smoking explained 2.7% and maternal weight 2.0%. There was a trend towards a negative relationship with glycated haemoglobin concentration at 6-12 weeks. Smoking and glycated haemoglobin concentration were strongly intercorrelated.

CONCLUSIONS

Most of the variance in standardised birthweight remains unexplained, but glycated haemoglobin concentration at 27-33 weeks is the most powerful explanatory variable. Possible reasons why there is not a stronger relationship between markers of maternal glycaemia and birthweight are discussed.

The effects of first-trimester diabetes control on the incidence of macrosomia

OBJECTIVE

The aim of this study was to explore the association between glycosylated hemoglobin concentrations during pregnancy and macrosomia.

STUDY DESIGN

One hundred thirty-six pregnancies in 120 women with type 1 or type 2 diabetes were studied longitudinally between January 1, 1991, and December 31, 1996. Glycosylated hemoglobin concentration and several maternal variables of mothers of neonates who were large for gestational age were compared with those of neonates who were appropriate for gestational age. Receiver-operator characteristic curves and regression analyses were used to determine a threshold related to macrosomia and to assess its predictive value.

RESULTS

Glycosylated hemoglobin concentrations throughout pregnancy were higher in mothers of neonates who were large for gestational age (n = 65) than in mothers of neonates who were appropriate for gestational age (n = 71, P <. 001). A first-trimester glycosylated hemoglobin concentration of >/=5.5% (3 SD above the normal mean) was established by receiver-operator characteristic curves as the strongest predictor of macrosomia and yielded an odds ratio of 24 in multiple logistic regression analysis.

CONCLUSION

Macrosomia is determined mainly by first-trimester diabetes control.

Fetal size at birth in relation to quality of blood glucose control in pregnancies complicated by pregestational diabetes mellitus

OBJECTIVE

To determine the relation between maternal levels of blood glucose and glycated haemoglobin (HbA1c) and infant size at birth in pregestational diabetes.

DESIGN

Longitudinal study from 6 to 14 weeks gestation. Women were treated intensively with insulin, aiming at normoglycaemia but avoiding hypoglycaemia. Blood glucose was determined six times daily, HbA1c every four weeks. Individual mean fasting and postprandial glucose levels were calculated for three-week periods of gestation. Birthweight > 2 SD or within +/- 2 SD for gestational age and gender was classified as large (LGA) or appropriate (AGA), respectively. Birthweight ratio was calculated as the ratio of birthweight to normal mean birthweight after correction for gestational age and gender.

PARTICIPANTS

One hundred and thirteen consecutive pregnant women with pregestational diabetes and their newborn infants.

RESULTS

Perinatal mortality was nil, the rates of spontaneous preterm delivery (8.9%) and severe maternal hypoglycaemia (4.4%) were low. Mothers with LGA infants (26%) had a significantly higher fasting glucose between weeks 27 and 32 than mothers of AGA infants (P < 0.01). Relative birthweight was significantly and independently associated with pre-pregnancy bodyweight (r = 0.24, P < 0.05) and fasting glucose at weeks 27 to 29 (r = 0.27, P < 0.01) but together could only explain 12.3% of the variation in birthweight (mult. r = 0.35, P < 0.01). HbA1c correlated with glucose levels but was unrelated to birthweight ratio. The fasting glucose level between weeks 30 and 32 was significantly interrelated with the fasting glucose level from each of the six preceding three-week periods.

CONCLUSION

Near normoglycaemia cannot be obtained in all patients, presumably due to intrinsic differences in glucoregulatory ability between individuals. The incidence of LGA infants was unexpectedly high. The modest abnormality in glycaemic control in mothers with LGA infants could only partly explain fetal oversize, suggesting that other factors must be implicated to explain fetal growth acceleration.

Diabetes

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