A review of contemporary modalities for identifying abnormal fetal growth

Fetal growth trajectories and their association with maternal and child characteristics

Background: The growth of the fetus is a complex process, influenced by genetic and environmental factors. Longitudinal patterns of fetal growth are required to fully understand this process, however to date, a paucity of data exists in this area.Objective: To identify fetal growth trajectories in-utero and to assess their association with maternal and child characteristics up to 5 years postnatal.Methods: Data from 781 mother-child pairs from the ROLO longitudinal birth cohort study were analyzed. The ROLO study was a randomized control trial of a low glycemic index diet in pregnancy to prevent recurrence of macrosomia. Fetal ultrasound measurements were recorded at 20 and 34 weeks gestation, and birth weight was recorded. Abdominal circumference (AC), weight (fetal weight, or birth weight), a standardized proxy for length (femur length or birth length, individually standardized), and AC:length ratio were examined for trajectory classes using latent class trajectory mixture models. Two-, three-, four-, and five-class models were evaluated for fit, using a linear (first order) trajectory over three time-points. ANOVA and chi-square tests were applied to test associations between trajectory membership and maternal and child characteristics up to age 5.Results: For AC, two fetal growth trajectories were identified, with 29% of participants on a "slow" trajectory and 71% on a "fast" trajectory. Those on a fast trajectory had higher rates of maternal impaired glucose tolerance (28.7 versus 16.5%, p<.001) and higher rates of mean child 5-year body mass index (BMI) centiles (64th versus 58th centile, p<.05) compared to those on the slow trajectory. For estimated fetal weight, four trajectories were identified, with 4% on a "very-slow" trajectory, 63% in a "moderate-slow" trajectory, 30% in a "moderate-fast" trajectory and 3% on a "very-fast" trajectory. Mothers with a fetus on the fastest trajectory had higher antenatal serum glucose levels (p<.05), and were more likely to deliver by cesarean section (59.1 versus 20%, p<.001). At 5 years of age, children on the fastest growth trajectory had the highest mean BMI centile (86th versus 60th centile, p<.05).Conclusions: This study shows that specific fetal growth trajectories may be associated with maternal serum glucose concentrations during pregnancy, mode of delivery and child BMI at 5 years of age. Diet and lifestyle measures that target maternal glucose levels during pregnancy may have lifelong benefits for children's BMI. Identifying those on an accelerated growth trajectory during fetal life provides a unique opportunity for antenatal and infant interventions that may have long-lasting health benefits.

A proteomic clock of human pregnancy

BACKGROUND

Early detection of maladaptive processes underlying pregnancy-related pathologies is desirable because it will enable targeted interventions ahead of clinical manifestations. The quantitative analysis of plasma proteins features prominently among molecular approaches used to detect deviations from normal pregnancy. However, derivation of proteomic signatures sufficiently predictive of pregnancy-related outcomes has been challenging. An important obstacle hindering such efforts were limitations in assay technology, which prevented the broad examination of the plasma proteome.

OBJECTIVE

The recent availability of a highly multiplexed platform affording the simultaneous measurement of 1310 plasma proteins opens the door for a more explorative approach. The major aim of this study was to examine whether analysis of plasma collected during gestation of term pregnancy would allow identifying a set of proteins that tightly track gestational age. Establishing precisely timed plasma proteomic changes during term pregnancy is a critical step in identifying deviations from regular patterns caused by fetal and maternal maladaptations. A second aim was to gain insight into functional attributes of identified proteins and link such attributes to relevant immunological changes.

STUDY DESIGN

Pregnant women participated in this longitudinal study. In 2 subsequent sets of 21 (training cohort) and 10 (validation cohort) women, specific blood specimens were collected during the first (7-14 weeks), second (15-20 weeks), and third (24-32 weeks) trimesters and 6 weeks postpartum for analysis with a highly multiplexed aptamer-based platform. An elastic net algorithm was applied to infer a proteomic model predicting gestational age. A bootstrapping procedure and piecewise regression analysis was used to extract the minimum number of proteins required for predicting gestational age without compromising predictive power. Gene ontology analysis was applied to infer enrichment of molecular functions among proteins included in the proteomic model. Changes in abundance of proteins with such functions were linked to immune features predictive of gestational age at the time of sampling in pregnancies delivering at term.

RESULTS

An independently validated model consisting of 74 proteins strongly predicted gestational age (P = 3.8 × 10^-14, R = 0.97). The model could be reduced to 8 proteins without losing its predictive power (P = 1.7 × 10^-3, R = 0.91). The 3 top ranked proteins were glypican 3, chorionic somatomammotropin hormone, and granulins. Proteins activating the Janus kinase and signal transducer and activator of transcription pathway were enriched in the proteomic model, chorionic somatomammotropin hormone being the top-ranked protein. Abundance of chorionic somatomammotropin hormone strongly correlated with signal transducer and activator of transcription-5 signaling activity in CD4 T cells, the endogenous cell-signaling event most predictive of gestational age.

CONCLUSION

Results indicate that precisely timed changes in the plasma proteome during term pregnancy mirror a proteomic clock. Importantly, the combined use of several plasma proteins was required for accurate prediction. The exciting promise of such a clock is that deviations from its regular chronological profile may assist in the early diagnoses of pregnancy-related pathologies, and point to underlying pathophysiology. Functional analysis of the proteomic model generated the novel hypothesis that chrionic somatomammotropin hormone may critically regulate T-cell function during pregnancy.

Preimplantation factor is an anti-apoptotic effector in human trophoblasts involving p53 signaling pathway

From the earliest stages of gestation, embryonic-maternal interaction has a key role in a successful pregnancy. Various factors present during gestation may significantly influence this type of juxta/paracrine interaction. PreImplantation Factor (PIF) is a recently identified factor with activity at the fetomaternal interface. PIF is secreted by viable embryos and directly controls placental development by increasing the invasive capacity of human extravillous trophoblasts (EVTs). To further specify PIF's role in the human placenta, we analyzed the genome-wide expression profile of the EVT in the presence of a synthetic PIF analog (sPIF). We found that sPIF exposure altered several pathways related to p53 signaling, survival and the immune response. Functional assays revealed that sPIF acts through the p53 pathway to reduce both early and late trophoblast apoptosis. More precisely, sPIF (i) decreases the phosphorylation of p53 at Ser-15, (ii) enhances the B-cell lymphoma-2 (BCL2) expression and (iii) reduces the BCL2-associated X protein (BAX) and BCL2 homologous antagonist killer (BAK) mRNA expression levels. Furthermore, invalidation experiments of TP53 allowed us to demonstrate that PIF's effects on placental apoptosis seemed to be essentially mediated by this gene. We have clearly shown that p53 and sPIF pathways could interact in human trophoblast and thus promotes cell survival. Furthermore, sPIF was found to regulate a gene network related to immune tolerance in the EVT, which emphasizes the beneficial effect of this peptide on the human placenta. Finally, the PIF protein levels in placentas from pregnancies affected by preeclampsia or intra-uterine growth restriction were significantly lower than in gestational age-matched control placentas. Taken as a whole, our results suggest that sPIF protects the EVT's functional status through a variety of mechanisms. Clinical application of sPIF in the treatment of disorders of early pregnancy can be envisioned.

An interaction between NDE1 and high birth weight increases schizophrenia susceptibility

Pre- and perinatal environmental factors have been shown to increase schizophrenia risk particularly when combined with genetic liability. The investigation of specific gene environment interactions in the etiology of psychiatric disorders has gained momentum. We used multivariate GEE regression modeling to investigate the interaction between genes of the DISC1 pathway and birth weight, in relation to schizophrenia susceptibility in a Finnish schizophrenia family cohort. The study sample consisted of 457 subjects with both genotype and birth weight information. Gender and place of birth were adjusted for in the models. We found a significant interaction between birth weight and two NDE1 markers in relation to increased schizophrenia risk: a four SNP haplotype spanning NDE1 (b=1.26, SE=0.5, p=0.012) and one of its constituent SNPs rs4781678 (b=1.33, SE=0.51, p=0.010). Specifically, high birth weight (>4000g) was associated with increased schizophrenia risk among subjects homozygous for the previously identified risk alleles. The study was based on a family study sample with high genetic loading for schizophrenia and thus our findings cannot directly be generalized as representing the general population. Our results suggest that the functions mediated by NDE1 during the early stages of neurodevelopment are susceptible to the additional disruptive effects of pre- and perinatal environmental factors associated with high birth weight, augmenting schizophrenia susceptibility.

Diagnostic accuracy of fundal height and handheld ultrasound-measured abdominal circumference to screen for fetal growth abnormalities

OBJECTIVE

We sought to compare fundal height and handheld ultrasound-measured fetal abdominal circumference (HHAC) for the prediction of fetal growth restriction (FGR) or large for gestational age.

STUDY DESIGN

This was a diagnostic accuracy study in nonanomalous singleton pregnancies between 24 and 40 weeks' gestation. Patients underwent HHAC and fundal height measurement prior to formal growth ultrasound. FGR was defined as estimated fetal weight less than 10%, whereas large for gestational age was defined as estimated fetal weight greater than 90%. Sensitivity and specificity were calculated and compared using methods described elsewhere.

RESULTS

There were 251 patients included in this study. HHAC had superior sensitivity and specificity for the detection of FGR (sensitivity, 100% vs 42.86%) and (specificity, 92.62% vs 85.24%). HHAC had higher specificity but lower sensitivity when screening for LGA (specificity, 85.66% vs 66.39%) and (sensitivity, 57.14% vs 71.43%).

CONCLUSION

HHAC could prove to be a valuable screening tool in the detection of FGR. Further studies are needed in a larger population.

Fetal and umbilical Doppler ultrasound in normal pregnancy

BACKGROUND

One of the main aims of routine antenatal care is to identify the 'at risk' fetus in order to apply clinical interventions which could result in reduced perinatal morbidity and mortality. Doppler ultrasound study of umbilical artery waveforms helps to identify the compromised fetus in 'high-risk' pregnancies and, therefore, deserves assessment as a screening test in 'low-risk' pregnancies.

OBJECTIVES

To assess the effects on obstetric practice and pregnancy outcome of routine fetal and umbilical Doppler ultrasound in unselected and low-risk pregnancies.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (28 February 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of umbilical and fetal vessels waveforms in unselected pregnancies compared with no Doppler ultrasound. Studies where uterine vessels have been assessed together with fetal and umbilical vessels have been included.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. In addition to standard meta-analysis, the two primary outcomes and five of the secondary outcomes were assessed using GRADE software and methodology.

MAIN RESULTS

We included five trials that recruited 14,624 women, with data analysed for 14,185 women. All trials had adequate allocation concealment, but none had adequate blinding of participants, staff or outcome assessors. Overall and apart from lack of blinding, the risk of bias for the included trials was considered to be low.Overall, routine fetal and umbilical Doppler ultrasound examination in low-risk or unselected populations did not result in increased antenatal, obstetric and neonatal interventions. There were no group differences noted for the review's primary outcomes of perinatal death and neonatal morbidity. Results for perinatal death were as follows: (average risk ratio (RR) 0.80, 95% confidence interval (CI) 0.35 to 1.83; four studies, 11,183 participants). Only one included trial assessed serious neonatal morbidity and found no evidence of group differences (RR 0.99, 95% CI 0.06 to 15.75; one study, 2016 participants).For the comparison of a single Doppler assessment versus no Doppler, evidence for group differences in perinatal death was detected (RR 0.36, 95% CI 0.13 to 0.99; one study, 3891 participants). However, these results are based on a single trial, and we would recommend caution when interpreting this finding.There was no evidence of group differences for the outcomes of caesarean section, neonatal intensive care admissions or preterm birth less than 37 weeks.When the quality of the evidence for the main comparison of 'All Doppler versus no Doppler' was assessed with GRADE software, the outcomes of perinatal death and serious neonatal morbidity data were graded as of low quality. Evidence for the outcome of stillbirth was graded according to regimen subgroups - with a moderate quality rating for stillbirth (fetal/umbilical vessels only) and a low quality rating for stillbirth (fetal/umbilical vessels + uterine artery vessels). Evidence for admission to neonatal intensive care unit was assessed as of moderate quality, and evidence for the outcomes of caesarean section and preterm birth less than 37 weeks was graded as of high quality.There is no available evidence to assess the effect on substantive long-term outcomes such as childhood neurodevelopment and no data to assess maternal outcomes, particularly maternal satisfaction.

AUTHORS' CONCLUSIONS

Existing evidence does not provide conclusive evidence that the use of routine umbilical artery Doppler ultrasound, or combination of umbilical and uterine artery Doppler ultrasound in low-risk or unselected populations benefits either mother or baby. Future studies should be designed to address small changes in perinatal outcome, and should focus on potentially preventable deaths.

Metabolomic profile of amniotic fluid to evaluate lung maturity: the diaphragmatic hernia lamb model

Background

Tracheal occlusion (TO) stimulates lung growth in fetuses affected with congenital diaphragmatic hernia (CDH) although the processes involved in lung maturation still remain unknown. The objective of this study was to evaluate the metabolomic profile of amniotic fluid (AF) following TO in fetal lamb model in order to obtain an indirect view of mechanisms involved in pulmonary reversal hypoplasia and biochemical maturity in response to fetal TO.

Methods

Liquid Chromatography Mass Spectrometry was performed on lamb AF samples at: age I (70 days’ gestation); age II (102 days’ gestation); age III (136 days’ gestation). CDH was induced at age I and TO at age II.

Results

Betaine, choline, creatinine were found significantly increased during gestation in the control group. The CDH group showed choline (p =0.007) and creatinine (p =0.004) decreases during pregnancy. In the TO group choline and creatinine profiles were restored.

Conclusions

Alveolar tissue and fetal global growth ameliorated after TO. Metabolomics provided useful information on biochemical details during lung maturation. Metabolomic profiling would help to identify the best time to perform TO, in order to increase survival of CDH affected patients.

Assessment of flow distribution in the mouse fetal circulation at late gestation by high-frequency Doppler ultrasound

This study used high-frequency ultrasound to evaluate the flow distribution in the mouse fetal circulation at late gestation. We studied 12 fetuses (embryonic day 17.5) from 12 pregnant CD1 mice with 40 MHz ultrasound to assess the flow in 11 vessels based on Doppler measurements of blood velocity and M-mode measurements of diameter. Specifically, the intrahepatic umbilical vein (UVIH), ductus venosus (DV), foramen ovale (FO), ascending aorta (AA), main pulmonary artery (MPA), ductus arteriosus (DA), descending thoracic aorta (DTA), common carotid artery (CCA), inferior vena cava (IVC), and right and left superior vena cavae (RSVC, LSVC) were examined, and anatomically confirmed by micro-CT. The mouse fetal circulatory system was found to be similar to that of the humans in terms of the major circuit and three shunts, but characterized by bilateral superior vena cavae and a single umbilical artery. The combined cardiac output (CCO) was 1.22 ± 0.05 ml/min, with the left ventricle (flow in AA) contributing 47.8 ± 2.3% and the right ventricle (flow in MPA) 52.2 ± 2.3%. Relative to the CCO, the flow percentages were 13.6 ± 1.0% for the UVIH, 10.4 ± 1.1% for the DV, 35.6 ± 2.4% for the DA, 41.9 ± 2.6% for the DTA, 3.8 ± 0.3% for the CCA, 29.5 ± 2.2% for the IVC, 12.7 ± 1.0% for the RSVC, and 9.9 ± 0.9% for the LSVC. The calculated flow percentage was 16.6 ± 3.4% for the pulmonary circulation and 31.2 ± 5.3% for the FO. In conclusion, the flow in mouse fetal circulation can be comprehensively evaluated with ultrasound. The baseline data of the flow distribution in normal mouse fetus serve as the reference range for future studies.

A predictor of small-for-gestational-age infant: oral glucose challenge test

OBJECTIVE

This study was performed to investigate the role of first-hour 50-g oral glucose challenge test (GCT) parameters in predicting the risk of delivering a small-for-gestational-age infant and to determine the accuracy of estimated fetal weight.

METHODS

We screened 2,643 pregnant women >20 years of age and excluded 552 patients according to exclusion criteria. Newborns were assigned to three groups as SGA(n:100), AGA(n:100), and LGA(n:100) according to birth weight. All mothers received 50-g GCT in their 24-28th weeks of gestation. We examined the relationship between birthweight and test results.

RESULTS

First-hour serum glucose level after the test significantly predicted babies with small for gestational age. Optimal cutoff value was obtained at a level of 74.5 mg/dl with 67% sensitivity and 55% specificity. The estimated fetal weight of Hadlock 5 formula was strongly correlated with the birth weight (Pearson r = 0.89).

CONCLUSION

Our study revealed that 50-g oral glucose challenge test may predict small-for-gestational-age cases with 67% sensitivity, and our data revealed that there is a significant correlation between estimated fetal weight of Hadlock 5 formula and the birth weight.

Longitudinal measurement of fetal thigh soft tissue parameters and its role in the prediction of birth weight

OBJECTIVE

The aim of this study was to profile longitudinal changes in thigh muscle and fat with gestation and to determine whether thigh measurements can improve the prediction of birth weight (BW).

METHODS

A prospective longitudinal study of subcutaneous soft tissue measurements was conducted in 328 singleton fetuses at 28 and 37 weeks gestation. Estimated fetal weight (EFW) was calculated using abdominal circumference, femur length, biparietal diameter, and head circumference.

RESULTS

The fetal abdominal subcutaneous tissue (FAST) and thigh muscle and fat show an increase with gestation. At 28 weeks gestation, the abdominal circumference, thigh fat, FAST, and EFW percentile were found to be significant predictors of BW. A combination of EFW percentile and thigh fat were found to be the optimal multivariate model at 28 weeks for predicting BW. At 37 weeks, BW prediction using EFW percentile, FAST, and thigh fat was the most accurate. The results revealed acceptable reproducibility for fetal thigh muscle and fat.

CONCLUSION

This study provides reference ranges for thigh fat and muscle at 28 and 37 weeks gestation. The inclusion of fetal thigh fat in the algorithm improves the predictive power for birth weight. This information is important to explore the role of fetal thigh in the detection of aberrant growth.