Fetal size and growth velocity in the prediction of the large for gestational age (LGA) infant in a glucose impaired population

Conditional standards for the quantification of foetal growth in an ethnic Chinese population: a longitudinal study

This was an observational study of low-risk singleton pregnancies in an ethnic Chinese population. Foetal biometric variables which included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL) were measured repeatedly. The standard views for measurement were obtained according to INTERGROWTH-21st criteria. A linear mixed model with fractional polynomial regression was used to describe the longitudinal design. The study included 1289 foetuses and a total of 5125 ultrasound scans, of which each foetus was scanned at least three times, the intervals between scans being at least two weeks. The parameters of the linear mixed models were estimated by Stata v.16 (College Station, TX). Using these parameters, the equations of the mean and variance for BPD, HC, AC and FL were constructed. The conditional percentiles or Z scores could be calculated based on the above equations and previous measurements of the same foetus. A spreadsheet was provided for implementation.Impact StatementWhat is already known on this subject? Longitudinal data derived from serial measurements are therefore appropriate for assessing both foetal size and foetal growth. At present, most reference charts of ethnic Chinese foetal biometry are derived from cross-sectional data, which can only assess foetal size.What do the results of this study add? In this study, we have constructed conditional standards for foetal biometry in an ethnic Chinese population and provided a spreadsheet for querying.What are the implications of these findings for clinical practice and/or further research? The conditional standards can be used to assess foetal growth in clinical practice. In the future, we hope that these foetal growth standards can be applied to determine whether abnormal growth increases the risk of adverse outcomes.

Accelerated fetal growth velocity across the third trimester is associated with increased shoulder dystocia risk among fetuses who are not large-for-gestational-age: A prospective observational cohort study

OBJECTIVE

To investigate whether fetuses with accelerated third trimester growth velocity are at increased risk of shoulder dystocia, even when they are not large-for-gestational-age (LGA; estimated fetal weight (EFW) >95th centile).

METHODS

Fetal growth velocity and birth outcome data were prospectively collected from 347 nulliparous women. Each had blinded ultrasound biometry performed at 28 and 36 weeks' gestation. Change in EFW and abdominal circumference (AC) centiles between 28-36 weeks were calculated, standardised over exactly eight weeks. We examined the odds of shoulder dystocia with increasing EFW and AC growth velocities among women with 36-week EFW ≤95th centile (non-LGA), who went on to have a vaginal birth. We then examined the relative risk (RR) of shoulder dystocia in cases of accelerated EFW and AC growth velocities (>30 centiles gained). Finally, we compared the predictive performances of accelerated fetal growth velocities to 36-week EFW >95th centile for shoulder dystocia among the cohort planned for vaginal birth.

RESULTS

Of the 226 participants who had EFW ≤95th centile at 36-week ultrasound and birthed vaginally, six (2.7%) had shoulder dystocia. For each one centile increase in EFW between 28-36 weeks, the odds of shoulder dystocia increased by 8% (odds ratio (OR [95% Confidence Interval (CI)]) = 1.08 [1.04-1.12], p<0.001). For each one centile increase in AC between 28-36 weeks, the odds of shoulder dystocia increased by 9% (OR[95%CI] = 1.09 [1.05-1.12], p<0.001). When compared to the rest of the cohort with normal growth velocity, accelerated EFW and AC velocities were associated with increased relative risks of shoulder dystocia (RR[95%CI] = 7.3 [1.9-20.6], p = 0.03 and 4.8 [1.7-9.4], p = 0.02 respectively). Accelerated EFW or AC velocities predicted shoulder dystocia with higher sensitivity and positive predictive value than 36-week EFW >95th centile.

CONCLUSIONS

Accelerated fetal growth velocities between 28-36 weeks' gestation are associated with increased risk of shoulder dystocia, and may predict shoulder dystocia risk better than the commonly used threshold of 36-week EFW >95th centile.

Fetal growth velocity in diabetics and the risk for shoulder dystocia: a case-control study

INTRODUCTION

Shoulder dystocia complicates up to 3% of vaginal births. The clinical ability to predict shoulder dystocia is limited, especially among diabetic women. We sought to evaluate if fetal growth trajectory measured from ultrasonographic (US) estimated fetal weight (EFW) percentiles was associated with increased risk for shoulder dystocia.

METHODS

We performed a case-control study among women diagnosed with diabetes at a single institution between 2005 and 2015. Two diabetic controls without shoulder dystocia based on the year of delivery were included for each woman with a shoulder dystocia. Women with a single EFW measurement, delivery by cesarean, or multiple gestation were excluded. Demographic and US data were collected. Fetal growth trajectory was calculated from EFW measurements in the last two growth ultrasound scans performed closest to delivery. We compared the odds of EFW percentile change per week above specific thresholds for shoulder dystocia cases versus controls. The following cutoffs were generated: a mean percentile per week increase of > 0%, ≥ 0.5%, ≥ 1%, and ≥ 2%. Among those with EFW percentile changes that decreased (<0%), we evaluated whether odds of an abdominal circumference (AC) > 75th percentile or an EFW > 75th percentile was higher for women with shoulder dystocia. The primary exposure was increased growth trajectory. Secondary outcomes included analysis of the following adverse neonatal outcomes: (i) low 5 minutes Apgar score, (ii) rates of NICU admission, and (iii) neonatal demise.

RESULTS

Of 3954 diabetics, we identified 68 cases with shoulder dystocia and 136 controls who did not have shoulder dystocia. Women who experienced a shoulder dystocia were more likely to be of advanced maternal age as compared to those without a shoulder dystocia (41.9% versus 23.5, p = .01); all other demographic characteristics were similar between groups. At growth trajectory cutoffs of > 0%, ≥ 0.5%, ≥ 1%, and ≥ 2% per week, odds ratios were increased among shoulder dystocia cases versus controls (OR = 1.8, 95% confidence interval (CI) = 0.9-3.3; OR = 1.6, 95% CI = 0.8-3.2; OR = 1.7, 95% CI = 0.7-3.9; and OR = 1.8, 95% CI = 0.6-5.3; respectively); however, this was not statistically significant. For women with fetal growth trajectories that decreased (< 0%), shoulder dystocia was associated with increased odds of fetal AC > 75th percentile and overall growth > 75th percentile (OR = 3.3, 95% CI = 1.5-7.1, OR = 4.8, 95% CI = 1.3-17.4, respectively). There was no difference in neonatal outcomes between shoulder dystocia cases and controls.

CONCLUSION

Future research is required to determine if fetal growth velocity proves to be a useful tool in identifying women at increased risk for shoulder dystocia. Larger studies are required for precise estimates of risk, and associated neonatal outcomes.

The effect of maternal obesity on fetal biometry, body composition, and growth velocity

Introduction: The aim of this secondary analysis was to investigate the relationship between maternal body mass index (BMI) and fetal biometry, body composition, and velocity measurements at 28 and 36 weeks gestation.Materials and methods: The current analysis involves 911 overweight or obese women who were randomized to the Standard Care group of the LIMIT randomized trial.Results: The fetus of women with Class 3 obesity (BMI ≥ 40.0) showed the greatest increase in all biometry z-scores, abdominal area (AA), and abdominal fat mass (AFM) compared with women classified as overweight (BMI 25.0-29.9). In women with Class 3 obesity, AA velocity was increased by 0.035 cm² (0.004, 0.066, p = .029) and the z-score velocity was increased by 0.238 (0.022, 0.453, p = .03). Estimated fetal weight (EFW) velocity for women with Class 3 obesity was higher than that of overweight women by 2.028 g per day (0.861, 3.196, p<.001) and the z-score velocity was also higher by 0.441 per day (0.196, 0.687, p < .001).Conclusions: Maternal obesity is associated with an increase in fetal abdominal circumference, AFM and area along with EFW velocity over time. Women with Class 3 obesity (BMI ≥ 40.0) may represent a higher risk group for perpetuating the intergenerational transmission of obesity to their offspring.

Individualized growth assessment: conceptual framework and practical implementation for the evaluation of fetal growth and neonatal growth outcome

Fetal growth abnormalities can pose significant consequences on perinatal morbidity and mortality of nonanomalous fetuses. The most widely accepted definition of fetal growth restriction is an estimated fetal weight less than the 10th percentile for gestational age according to population-based criteria. However, these criteria do not account for the growth potential of an individual fetus, nor do they effectively separate constitutionally small fetuses from ones that are malnourished. Furthermore, conventional approaches typically evaluate estimated fetal weight at a single time point, rather than using serial scans, to evaluate growth. This article provides a conceptual framework for the individualized growth assessment of a fetus/neonate based on measuring second-trimester growth velocity of fetal size parameters to estimate growth potential. These estimates specify size models that generate individualized third-trimester size trajectories and predict birth characteristics. Comparisons of measured and predicted values are used to separate normally growing fetuses from those with growth abnormalities. This can be accomplished with individual anatomical parameters or sets of parameters. A practical and freely available software (Individualized Growth Assessment Program) has been developed to allow implementation of this approach for clinical and research purposes.

A reference range of fetal abdominal circumference growth velocity between 20 and 36 weeks' gestation

OBJECTIVE

To create a single equation and reference range for abdominal circumference growth velocity (ACGV) between 20 and 36 weeks in singleton pregnancies.

METHOD

Observational study of pregnant women having routine scans for abdominal circumference (AC) at 20 and 36 weeks' gestation. Exclusion criteria were multiple pregnancy, abnormal karyotype, major fetal abnormalities, and absent data on first-trimester dating. Scan image quality and AC measurement reliability were assessed according to INTERGROWTH-21st criteria. Regression models for the AC mean and standard deviation were fitted separately at 20 and 36 weeks, and z scores were calculated. Abdominal circumference growth velocity was defined as the z score difference between 20 and 36 weeks divided by the interval in days and multiplied by 100.

RESULTS

The study population included 3334 fetuses. The equation for ACGV is (((AC₃₆  - 53.090 - 1.081*GA₃₆ )/(0.057638*GA₃₆  + 0.622741)) - ((AC₂₀  + 68.349 - 1.571*GA₂₀ )/(0.06265*GA₂₀  - 2.55361)))*100/(GA₃₆  - GA₂₀ ), where AC is expressed in millimeters and GA is gestational age in days. The 3rd, 5th, 10th, 50th, 90th, 95th, and 97th centiles are -1.8997, -1.6785, -1.3091, -0.0069, 1.3255, 1.7279, 1.9973, respectively.

CONCLUSION

We have defined ACGV between 20 and 36 weeks, and we have established its reference range. Further studies are needed to evaluate the clinical significance of growth patterns in the tail ends of this distribution.

Implications of maternal obesity on fetal growth and the role of ultrasound

Over fifty percent of women entering pregnancy are overweight or obese. This has a significant impact on short and long term maternal and infant health outcomes, and the intergenerational effects of obesity are now a major public health problem globally. Areas covered: There are two major pathways contributing to fetal growth. Glucose and insulin directly affect growth, while other substrates such as leptin, adiponectin and insulin-like growth factors indirectly influence growth through structural and morphological effects on the placenta, uteroplacental blood flow, and regulation of placental transporters. Advances in ultrasonography over the past decade have led to interest in the prediction of the fetus at risk of overgrowth and adiposity utilizing both standard ultrasound biometry and fetal body composition measurements. However, to date there is no consensus regarding the definition of fetal overgrowth, its reporting, and clinical management. Expert commentary: Maternal dietary intervention targeting the antenatal period appear to be too late to sufficiently affect fetal growth. The peri-conceptual period and early pregnancy are being evaluated to determine if the intergenerational effects of maternal obesity can be altered to improve newborn, infant and child health.

Antenatal dietary and lifestyle advice for women who are overweight or obese and the effect on fetal growth and adiposity: the LIMIT randomised trial

OBJECTIVE

To report the influence of maternal overweight and obesity on fetal growth and adiposity and effects of an antenatal dietary and lifestyle intervention among these women on measures of fetal growth and adiposity as secondary outcomes of the LIMIT Trial.

DESIGN

Randomised controlled trial.

SETTING

Public maternity hospitals in metropolitan Adelaide, South Australia.

POPULATION

Pregnant women with a body mass index ≥ 25 kg/m(2), and singleton gestation between 10(+0) and 20(+0) weeks.

METHODS

Women were randomised to Lifestyle Advice or continued Standard Care and offered two research ultrasound scans at 28 and 36 weeks of gestation.

MAIN OUTCOME MEASURES

Ultrasound measures of fetal growth and adiposity.

RESULTS

For each fetal body composition parameter, mean Z-scores were substantially higher when compared with population standards. Fetuses of women receiving Lifestyle Advice demonstrated significantly greater mean mid-thigh fat mass, when compared with fetuses of women receiving Standard Care (adjusted difference in means 0.17; 95% CI 0.02-0.32; P = 0.0245). While subscapular fat mass increased between 28 and 36 weeks of gestation in fetuses in both treatment groups, the rate of adipose tissue deposition slowed among fetuses of women receiving Lifestyle Advice, when compared with fetuses of women receiving Standard Care (P = 0.0160). No other significant differences were observed.

CONCLUSIONS

These findings provide the first evidence of changes to fetal growth following an antenatal dietary and lifestyle intervention among women who are overweight or obese.

Comparison of 2- and 3-Dimensional Sonography for Estimation of Birth Weight and Neonatal Adiposity in the Setting of Suspected Fetal Macrosomia

OBJECTIVES

To compare the accuracy of 2-dimensional (2D) and 3-dimensional (3D) fetal measurements for prediction of birth weight Z score and neonatal adiposity (percent body fat) in the setting of suspected fetal macrosomia.

METHODS

We conducted a prospective observational study of term singleton pregnancies with suspected macrosomia. Patients were enrolled on admission to labor and delivery and underwent sonographic examinations. Within 48 hours of delivery, neonatal anthropometric measurements were obtained.

RESULTS

Thirty-four neonates were included in the analysis. Mothers were very obese (mean body mass index ± SD, 39.1 ± 7.8 kg/m(2)); 56.5% were white; and 39.1% had diabetes. Neonates were 38% female and had a mean birth weight of 3940.0 ± 496.8 g, percent body fat of 18.5% ± 4.0%, and Ponderal index of 2.8 ± 0.3 g/cm(3). Mean 2D estimated fetal weight was 3973 ± 443 g; mean 3D estimated fetal weight was 3803 ± 528 g; and mean thigh volume was 102.5 ± 19.6 cm(3). Both 2D and 3D measurements accounted for about half the variance in predicted birth weight (R(2) for 2D = 0.53, 71% within 10% of birth weight; R(2) for 3D = 0.47, 65% within 10% of birth weight). Thigh volume Z score was the prenatal parameter most highly correlated with both birth weight Z score (R(2) = 0.52; r = 0.72; 95% confidence interval, 0.54-0.84; P < .001) and percent body fat (R(2) = 0.22; r = 0.47; 95% confidence interval, 0.17-0.69; P = .04).

CONCLUSIONS

In our population of fetuses with suspected macrosomia, fractional thigh volume was the best sonographic estimate of neonatal percent body fat and birth weight Z score. Future research on prediction of neonatal weight and adiposity in macrosomic fetuses should include an estimate of fetal soft tissue given the generalized increase in body fat of these fetuses.

Genetic risk score for prediction of newborn adiposity and large-for-gestational-age birth

CONTEXT

Macrosomic infants are at increased risk for adverse metabolic outcomes. Improving prediction of large-for-gestational-age (LGA) birth may help prevent these outcomes.

OBJECTIVE

This study sought to determine whether genes associated with obesity-related traits in adults are associated with newborn size, and whether a genetic risk score (GRS) predicts LGA birth.

SETTING AND DESIGN

Single nucleotide polymorphisms (SNPs) in 40 regions associated with adult obesity-related traits were tested for association with newborn size. GRS's for birth weight and sum of skinfolds (SSF) specific to ancestry were calculated using the most highly associated SNP for each ancestry in genomic regions with one or more SNPs associated with birth weight and/or SSF in at least one ancestry group or meta-analyses.

PARTICIPANTS

Newborns from the Hyperglycemia Adverse Pregnancy Outcomes Study were studied (942 Afro-Caribbean, 1294 Northern European, 573 Mexican-American, and 1182 Thai).

OUTCOME MEASURES

Birth weight >90th percentile (LGA) and newborn SSF >90th percentile were primary outcomes.

RESULTS

After adjustment for ancestry, sex, gestational age at delivery, parity, maternal genotype, maternal smoking/alcohol intake, age, body mass index, height, blood pressure and glucose, 25 and 23 SNPs were associated (P < .001) with birth weight and newborn SSF, respectively. The GRS was highly associated with both phenotypes as continuous variables across all ancestries (P ≤ 1.6 × 10(-19)) and improved prediction of birth weight and SSF >90th percentile when added to a baseline model incorporating the covariates listed above.

CONCLUSIONS

A GRS comprised of SNPs associated with adult obesity-related traits may provide an approach for predicting LGA birth and newborn adiposity beyond established risk factors.

Early prediction of macrosomia based on an analysis of second trimester amniotic fluid by capillary electrophoresis

AIM

To identify, using capillary electrophoresis and chemometrics, early biomarkers in human amniotic fluid of large-for-gestational-age (LGA) infants.

MATERIALS & METHODS

Second trimester amniotic fluid samples, obtained from mothers undergoing age-related amniocentesis, were analyzed by capillary electrophoresis. Electropherogram data were aligned using correlation-optimized warping. A genetic algorithm using a Bayesian evaluation function and a leave-one-out cross-validation strategy for two birth outcomes: appropriate-for-gestational-age (AGA) versus LGA infants.

RESULTS

LGA (n = 23) was differentiated from AGA (n = 86) with a sensitivity of 100% and a specificity of 98% using only two wavelets. The first wavelet is associated with albumin and the second wavelet with an unknown small molecule.

CONCLUSION

The approach developed herein allows LGA fetuses to be metabolically distinguished from AGA fetuses early in pregnancy and indicates that the birth of a LGA infant is already associated with an altered biochemical profile by the second trimester.

[Obstetrical care in gestational diabetes and management of preterm labor]

OBJECTIVES

Search for data necessary to elaborate recommendations for obstetrical care in gestational diabetes and management of preterm labor.

METHODS

Systematic review of the literature and levels of evidence.

RESULTS

In case of gestational diabetes and in the absence of disease or other risk factor associated, there is no evidence to support a systematic rate of clinical follow up different from other pregnancy. The relevance of ultrasound estimates of fetal weight is limited. No formula is superior to others or to the simple measurement of abdominal circumference for the prediction of macrosomia (EL3). The usefulness of the research septal hypertrophy is not demonstrated (EL4). The systematic application of umbilical Doppler has no proven benefits in the absence of growth restriction or hypertension associated (EL4). Monthly ultrasound monitoring of the fetus can be proposed for diabetics on insulin or poorly controlled. In cases of gestational diabetes controlled by diet, cardiotocography of fetal heart rate has not proven useful. In poorly controlled diabetes and/or on insulin, the registration may be discussed taking into account other risk factors associated (EL4). A weekly recording of fetal heart rate is often recommended in case of type 2 diabetes discovered during pregnancy. In case of preterm labor, calcium channel blockers and oxytocin antagonists can be used without specific precautions. The risk of using beta-adrenergic outweighs the benefit. Administration of corticosteroid can be done under glycemic control, with insulin therapy if necessary. Screening test for gestational diabetes should not be performed within few days after last steroid injection.

Growth of fetal lean mass and fetal fat mass in gestational diabetes

OBJECTIVES

This study was carried out to investigate growth indicators of fetal lean mass and fat mass in the second half of the gestational period in pregnancies complicated by gestational diabetes mellitus (GDM) in comparison to normal control pregnancies.

METHODS

Forty-three control and 171 GDM pregnancies were followed longitudinally by ultrasound examinations, measuring both traditional biometric parameters and six non-traditional parameters for the evaluation of lean and fat mass. A mixed linear model derived from the log-Count function was used to model fetal growth and to make comparisons between groups. Factor analysis was used to evaluate the associations between gestational diabetes and fetal size and fetal fat/lean mass ratios.

RESULTS

A total of 506 scans were obtained in the 214 pregnancies, a mean of 2.4 scans per pregnancy (range 2-5). Maternal age, prepregnancy weight and body mass index were significantly higher in GDM pregnancies. Fetuses of GDM pregnancies showed greater growth, at the same gestational age, for each lean and fat non-traditional parameter, having a significantly greater amount of total tissue mass and a higher fat mass/lean mass ratio, independent of gestational age, in comparison to control pregnancies.

CONCLUSIONS

A non-invasive, repeatable evaluation of fetal body composition in utero could represent a useful method for the early detection of growth abnormalities and for direct estimation of the fetal metabolic status.

Management of gestational diabetes mellitus

The incidence of gestational diabetes mellitus (GDM) is on the increase and, if not diagnosed, managed and treated adequately, can have unfavorable maternal and fetal outcomes. Several studies have shown that glycemic values considered as adequate in the past when monitoring GDM failed to contain these adverse outcomes and randomized trials are needed to ascertain whether these targets should be lowered. Dietary restrictions remain the mainstay of GDM management and suitable physical exercise can help too. The use of rapid-acting insulin analogues (lispro and aspart) are novel treatments for improving metabolic control by reducing postprandial glycemia, while long-acting insulin analogues need to be evaluated by further studies for safety in clinical use before they can be prescribed. Numerous studies have found glyburide and metformin safe in women with GDM but more randomized controlled trials are needed, with a long-term follow-up of mother and child, to confirm these results.

TYPE 1 DIABETES IN PREGNANCY; INFLUENCES ON MOTHER AND FETUS

Type 1 diabetes complicates around 1 in 200 to 300 pregnancies in the United Kingdom. Historically maternal type 1 diabetes carried very high risks for mother and child. Introduction of insulin led to an immediate, marked decline in the previously very high rates of maternal mortality; in contrast an improvement in perinatal outcomes occurred more slowly but was nevertheless dramatic. This is strikingly demonstrated by the temporal decline in perinatal mortality in offspring of mothers with type 1 diabetes which was virtually universal before use of insulin in the 1920's, likely remained in excess of 20% even in the 1960's and fell to under 4% by the 1990's. The reasons for this more gradual improvement in perinatal outcomes cannot be defined with precision but will have been influenced by improved glycaemic management with use of intensive, multiple dose insulin treatment and home glucose monitoring; improvements in obstetric and neonatal management, and better management of complications of diabetes before and during pregnancy. In 1989 the St Vincent declaration proposed that pregnancy outcomes in women with type 1 diabetes should approximate those of the non-diabetic population. While the long term improvements in fetal outcomes have been dramatic, contemporary surveys confirm a persistent doubling or more of rates of congenital anomaly and a three to four fold increase in perinatal mortality in the UK and other European countries which will require further clinical innovation to overcome.