Fetal growth risk curves: defining levels of fetal growth restriction by neonatal death risk

Association between risk of infant death and birth-weight z scores according to gestational age: A nationwide study using the Finnish Medical Birth Register

OBJECTIVE

To investigate the association between infant mortality and birth weight using estimated fetal weight (EFW) versus birth-weight charts, by gestational age (GA).

METHODS

This nationwide population-based study used data from the Finnish Medical Birth Register from 2006 to 2016 on non-malformed singleton live births at 24-41+6 weeks of gestation (N = 563 630). The outcome was death in the first year of life. Mortality risks by birth-weight z score, defined as a continuous variable using Maršál's EFW and Sankilampi's birth-weight charts, were assessed using generalized additive models by GA (24-27+6, 28-31+6, 32-36+6, 37-38+6, 39-41+6 weeks). We calculated z score thresholds associated with a two- and three-fold increased risk of infant death compared with newborns with a birth weight between 0 and 0.675 standard deviations.

RESULTS

The z score thresholds (with corresponding centiles in parentheses) associated with a two-fold increase in infant mortality were: -3.43 (<0.1) at 24-27+6 weeks, -3.46 (<0.1) at 28-31+6 weeks, -1.29 (9.9) at 32-36+6 weeks, -1.18 (11.9) at 37-38+6 weeks, and - 1.34 (9.0) at 39-41+6 weeks according to the EFW chart. These values were - 2.43 (0.8), -2.62 (0.4), -1.34 (9.0), -1.37 (8.5), and - 1.43 (7.6) according to the birth-weight chart.

CONCLUSION

The association between birth weight and infant mortality varies by GA whichever chart is used, suggesting that different thresholds for the screening of growth anomalies could be used across GA to identify high-risk newborns.

Outcomes of induction vs prelabor cesarean delivery at <33 weeks for hypertensive disorders of pregnancy

BACKGROUND

Hypertensive disorders of pregnancy are the leading cause of indicated preterm birth; however, the optimal delivery approach for pregnancies complicated by preterm hypertensive disorders of pregnancy remains uncertain.

OBJECTIVE

This study aimed to compare maternal and neonatal morbidity in patients with hypertensive disorders of pregnancy who either went induction of labor or prelabor cesarean delivery at <33 weeks' gestation. In addition, we aimed to quantify the length of induction of labor and rate of vaginal delivery in those who underwent induction of labor.

STUDY DESIGN

This is a secondary analysis of an observational study which included 115,502 patients in 25 hospitals in the United States from 2008 to 2011. Patients were included in the secondary analysis if they were delivered for pregnancy associated hypertension (gestational hypertension or preeclampsia) between 230 and <330 weeks' gestation; and were excluded for known fetal anomalies, multiple gestation, fetal malpresentation or demise, or a contraindication to labor. Maternal and neonatal adverse composite outcomes were evaluated by intended mode of delivery. Secondary outcomes were duration of labor induction and rate of cesarean delivery in those who underwent labor induction.

RESULTS

A total of 471 patients met inclusion criteria, of whom 271 (58%) underwent induction of labor and 200 (42%) underwent prelabor cesarean delivery. Composite maternal morbidity was 10.2% in the induction group and 21.1% in the cesarean delivery group (unadjusted odds ratio, 0.42 [0.25-0.72]; adjusted odds ratio, 0.44 [0.26-0.76]). Neonatal morbidity in the induction group vs the cesarean delivery was 51.9% and 63.8 %, respectively (unadjusted odds ratio, 0.61 [0.42-0.89]; adjusted odds ratio, 0.71 [0.48-1.06]). The frequency of vaginal delivery in the induction group was 53% (95% confidence interval, 46.8-58.7) and the median duration of labor was 13.9 hours (interquartile range, 8.7-22.2). The frequency of vaginal birth was higher in patients at or beyond 29 weeks (39.9% at 240-286 weeks, 56.3% at 290-<330 weeks; P=.01).

CONCLUSION

Among patients delivered for hypertensive disorders of pregnancy <330 weeks, labor induction compared with prelabor cesarean delivery is associated with significantly lower odds of maternal but not neonatal morbidity. More than half of patients induced delivered vaginally, with a median duration of labor induction of 13.9 hours.

Evolutionary perspective of uteroplacental malperfusion: subjacent insult common to most pregnancy complications

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Competing-risks model for prediction of small-for-gestational-age neonate from estimated fetal weight at 19-24 weeks' gestation

OBJECTIVE

To develop further a new competing-risks model for the prediction of a small-for-gestational-age (SGA) neonate, by including second-trimester ultrasonographic estimated fetal weight (EFW).

METHODS

This was a prospective observational study in 96 678 women with singleton pregnancy undergoing routine ultrasound examination at 19-24 weeks' gestation. All pregnancies had ultrasound biometry assessment, and EFW was calculated according to the Hadlock formula. We refitted in this large dataset a previously described competing-risks model for the joint distribution of gestational age (GA) at delivery and birth-weight Z-score, according to maternal demographic characteristics and medical history, to obtain the prior distribution. The continuous likelihood of the EFW was fitted conditionally to GA at delivery and birth-weight Z-score and modified the prior distribution, according to Bayes' theorem, to obtain individualized distributions for GA at delivery and birth-weight Z-score and therefore patient-specific risks for any cut-offs for GA at delivery and birth-weight Z-score. We assessed the discriminative ability of the model for predicting SGA with, without or independently of pre-eclampsia occurrence. A calibration study was carried out. Performance of screening was evaluated for SGA defined according to the Fetal Medicine Foundation birth-weight charts.

RESULTS

The distribution of EFW, conditional to both GA at delivery and birth-weight Z-score, was best described by a regression model. For earlier gestations, the association between EFW and birth weight was steeper. The prediction of SGA by maternal factors and EFW improved for increasing degree of prematurity and greater severity of smallness but not for coexistence of pre-eclampsia. Screening by maternal factors predicted 31%, 34% and 39% of SGA neonates with birth weight < 10^th percentile delivered at ≥ 37, < 37 and < 30 weeks' gestation, respectively, at a 10% false-positive rate, and, after addition of EFW, these rates increased to 38%, 43% and 59%, respectively; the respective rates for birth weight < 3^rd percentile were 43%, 50% and 64%. The addition of EFW improved the calibration of the model.

CONCLUSION

In the competing-risks model for prediction of SGA, the performance of screening by maternal characteristics and medical history is improved by the addition of second-trimester EFW. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Competing-risks model for prediction of small-for-gestational-age neonate from maternal characteristics, serum pregnancy-associated plasma protein-A and placental growth factor at 11-13 weeks' gestation

OBJECTIVES

To expand a new competing-risks model for prediction of a small-for-gestational-age (SGA) neonate, by the addition of pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PlGF), and to evaluate and compare PAPP-A and PlGF in predicting SGA.

METHODS

This was a prospective observational study of 60 875 women with singleton pregnancy undergoing routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation. We fitted a folded-plane regression model for the PAPP-A and PlGF likelihoods. A previously developed maternal history model and the likelihood models were combined, according to Bayes' theorem, to obtain individualized distributions for gestational age (GA) at delivery and birth-weight Z-score. We assessed the discrimination and calibration of the model. McNemar's test was used to compare the detection rates for SGA with, without or independently of pre-eclampsia (PE) occurrence, of different combinations of maternal history, PAPP-A and PlGF, for a fixed false-positive rate.

RESULTS

The distributions of PAPP-A and PlGF depend on both GA at delivery and birth-weight Z-score, in the same continuous likelihood, according to a folded-plane regression model. The new approach offers the capability for risk computation for any desired birth-weight Z-score and GA at delivery cut-off. PlGF was consistently and significantly better than PAPP-A in predicting SGA delivered before 37 weeks, especially in cases with co-existence of PE. PAPP-A had similar performance to PlGF for the prediction of SGA without PE. At a fixed false-positive rate of 10%, the combination of maternal history, PlGF and PAPP-A predicted 33.8%, 43.8% and 48.4% of all cases of a SGA neonate with birth weight < 10^th percentile delivered at ≥ 37, < 37 and < 32 weeks' gestation, respectively. The respective values for birth weight < 3^rd percentile were 38.6%, 48.7% and 51.0%. The new model performed well in terms of risk calibration.

CONCLUSIONS

The combination of PAPP-A and PlGF values with maternal characteristics, according to Bayes' theorem, improves prediction of SGA. PlGF is a better predictor of SGA than PAPP-A, especially when PE is present. The new competing-risks model for SGA can be tailored to each pregnancy and to the relevant clinical requirements. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Competing-risks model for prediction of small-for-gestational-age neonate from biophysical and biochemical markers at 11-13 weeks' gestation

OBJECTIVE

To develop a new competing-risks model for the prediction of a small-for-gestational-age (SGA) neonate, based on maternal factors and biophysical and biochemical markers at 11-13 weeks' gestation.

METHODS

This was a prospective observational study in 60 875 women with singleton pregnancy undergoing routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation. All pregnancies had pregnancy-associated plasma protein-A and placental growth factor (PlGF) measurements, 59 001 had uterine artery pulsatility index (UtA-PI) measurements and 58 479 had mean arterial pressure measurements; 57 131 cases had complete data for all biomarkers. We used a previously developed competing-risks model for the joint distribution of gestational age (GA) at delivery and birth-weight Z-score, according to maternal demographic characteristics and medical history. The likelihoods of the biophysical markers were developed by fitting folded-plane regression models, a technique that has already been used in previous studies for the likelihoods of biochemical markers. The next step was to modify the prior distribution by the likelihood, according to Bayes' theorem, to obtain individualized distributions for GA at delivery and birth-weight Z-score. We used the 57 131 cases with complete data to assess the discrimination and calibration of the model for predicting SGA with, without or independently of pre-eclampsia, by different combinations of maternal factors and biomarkers.

RESULTS

The distribution of biomarkers, conditional to both GA at delivery and birth-weight Z-score, was best described by folded-plane regression models. These continuous two-dimensional likelihoods update the joint distribution of birth-weight Z-score and GA at delivery that has resulted from a competing-risks approach; this method allows application of user-defined cut-offs. The best biophysical predictor of preterm SGA was UtA-PI and the best biochemical marker was PlGF. The prediction of SGA was consistently better for increasing degree of prematurity, greater severity of smallness, coexistence of PE and increasing number of biomarkers. The combination of maternal factors with all biomarkers predicted 34.3%, 48.6% and 59.1% of all cases of a SGA neonate with birth weight < 10^th percentile delivered at ≥ 37, < 37 and < 32 weeks' gestation, at a 10% false-positive rate. The respective values for birth weight < 3^rd percentile were 39.9%, 53.2% and 64.4%, and for birth weight < 3^rd percentile with pre-eclampsia they were 46.3%, 66.8% and 80.4%. The new model was well calibrated.

CONCLUSIONS

This study has presented a single continuous two-dimensional model for prediction of SGA for any desired cut-offs of smallness and GA at delivery, laying the ground for a personalized antenatal plan for predicting and managing SGA, in the milieu of a new inverted pyramid of prenatal care. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Prognostic value of diffusion-weighted magnetic resonance imaging of brain in fetal growth restriction: results of prospective multicenter study

OBJECTIVE

To measure prospectively apparent diffusion coefficient (ADC) values between 28 and 32 weeks of gestation in different cerebral territories of fetuses with estimated fetal weight (EFW) ≤ 5^th centile, and analyze their association with adverse perinatal outcome.

METHODS

This was a prospective study involving six tertiary-level perinatal centers. In the period 22 November 2016 to 11 September 2017, we included singleton, small-for-gestational-age (SGA) fetuses with EFW ≤ 5^th percentile, between 28 and 32 weeks of gestation, regardless of the umbilical artery Doppler and maternal uterine artery Doppler findings. A fetal magnetic resonance imaging (MRI) examination with diffusion-weighted sequences (DWI) was performed within 14 days following inclusion and before 32 weeks. ADC values were calculated in the frontal and occipital white matter, basal ganglia and cerebellar hemispheres. An ultrasound examination was performed within 1 week prior to the MRI examination. The primary outcome was a composite measure of adverse perinatal outcome, defined as any of the following: perinatal death; admission to neonatal intensive care unit with mechanical ventilation > 48 h; necrotizing enterocolitis; Grade III-IV intraventricular hemorrhage; periventricular leukomalacia. A univariate comparison of median ADC values in all cerebral territories between fetuses with and those without adverse perinatal outcome was performed. The association between ADC values and adverse perinatal outcome was then analyzed using multilevel logistic regression models to adjust for other common prognostic factors for growth-restricted fetuses.

RESULTS

MRI was performed in 64 patients, of whom five were excluded owing to fetal movement artifacts on DWI and two were excluded for termination of pregnancy with no link to fetal growth restriction (FGR). One intrauterine death occurred secondary to severe FGR. Among the 56 liveborn neonates, delivered at a mean ± SD gestational age of 33.6 ± 3.0 weeks, with a mean birth weight of 1441 ± 566 g, four neonatal deaths occurred. In addition, two neonates required prolonged mechanical ventilation, one of whom also developed necrotizing enterocolitis. Overall, therefore, seven out of 57 (12.3%) cases had an adverse perinatal outcome (95% CI, 3.8-20.8%). The ADC values in the frontal region were significantly lower in the group with adverse perinatal outcome vs those in the group with favorable outcome (mean values of both hemispheres, 1.68 vs 1.78 × 10^-3  mm² /s; P = 0.04). No significant difference in ADC values was observed between the two groups in any other cerebral territory. A cut-off value of 1.70 × 10^-3  mm² /s was associated with a sensitivity of 57% (95% CI, 18-90%), a specificity of 78% (95% CI, 63-88%), a positive predictive value of 27% (95% CI, 8-55%) and a negative predictive value of 93% (95% CI, 80-98%) for the prediction of adverse perinatal outcome. A mean frontal ADC value < 1.70 × 10^-3  mm² /s was not associated significantly with an increased risk of adverse perinatal outcome, either in the univariate analysis (P = 0.07), or when adjusting for gestational age at MRI and fetal sex (odds ratio (OR), 6.06 (95% CI, 0.9-37.1), P = 0.051) or for umbilical artery Doppler (OR, 6.08 (95% CI, 0.89-41.44)).

CONCLUSION

This first prospective, multicenter, cohort study using DWI in the setting of SGA found lower ADC values in the frontal white-matter territory in fetuses with, compared with those without, adverse perinatal outcome. To determine the prognostic value of these changes, further standardized evaluation of the neurodevelopment of children born with growth restriction is required. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

An outcome-based definition of low birthweight for births in low- and middle-income countries: a secondary analysis of the WHO global survey on maternal and perinatal health

Background

2500 g has been used worldwide as the definition of low birthweight (LBW) for almost a century. While previous studies have used statistical approaches to define LBW cutoffs, a LBW definition using an outcome-based approach has not been evaluated. We aimed to identify an outcome-based definition of LBW for live births in low- and middle-income countries (LMICs), using data from a WHO cross-sectional survey on maternal and perinatal health outcomes in 23 countries.

Methods

We performed a secondary analysis of all singleton live births in the WHO Global Survey (WHOGS) on Maternal and Perinatal Health, conducted in African and Latin American countries (2004–2005) and Asian countries (2007–2008). We used a two-level logistic regression model to assess the risk of early neonatal mortality (ENM) associated with subgroups of birthweight (< 1500 g, 1500–2499 g with 100 g intervals; 2500–3499 g as the reference group). The model adjusted for potential confounders, including maternal complications, gestational age at birth, mode of birth, fetal presentation and facility capacity index (FCI) score. We presented adjusted odds ratios (aORs) with 95% confidence intervals (CIs). A lower CI limit of at least two was used to define a clinically important definition of LBW.

Results

We included 205,648 singleton live births at 344 facilities in 23 LMICs. An aOR of at least 2.0 for the ENM outcome was observed at birthweights below 2200 g (aOR 3.8 (95% CI; 2.7, 5.5) of 2100–2199 g) for the total population. For Africa, Asia and Latin America, the 95% CI lower limit aORs of at least 2.0 were observed when birthweight was lower than 2200 g (aOR 3.6 (95% CI; 2.0, 6.5) of 2100–2199 g), 2100 g (aOR 7.4 (95% CI; 5.1, 10.7) of 2000–2099 g) and 2200 g (aOR 6.1 (95% CI; 3.4, 10.9) of 2100–2199 g) respectively.

Conclusion

A birthweight of less than 2200 g may be an outcome-based threshold for LBW in LMICs. Regional-specific thresholds of low birthweight (< 2200 g in Africa, < 2100 g in Asia and < 2200 g in Latin America) may also be warranted.

Electronic supplementary material

The online version of this article (10.1186/s12887-019-1546-z) contains supplementary material, which is available to authorized users.

Prescriptive birthweight charts can improve the prediction of adverse outcomes in very preterm infants who are small for gestational age

AIM

We compared three anthropometric charts to determine which provided the best predictions for adverse outcomes in very preterm small for gestational age (SGA) infants to address a lack of consensus on this subject.

METHODS

This was a retrospective cohort study of infants born below 32 weeks, who were admitted to two-level three neonatal intensive care units in The Netherlands from 2008 to 2013. The birthweights of 1720 infants were classified as SGA using a conventional, gender-specific birthweight chart, based on births in The Netherlands between 2000 and 2007, a prescriptive, gender-specific birthweight chart, based on the same data but without risk factors for intrauterine growth restriction (IUGR), and a non-gender-specific foetal weight chart derived from American ultrasonographic measurements.

RESULTS

The conventional, prescriptive and foetal weight charts classified 126 (7.3%), 494 (28.7%) and 630 (36.6%) infants as SGA. The prescriptive chart, which excluded IUGR, identified 368 SGA infants with significantly increased risks of neonatal mortality and morbidity. The 136 SGA infants just classified by the American foetal weight chart were not at increased risk.

CONCLUSION

The prescriptive birthweight chart, which excluded infants with IUGR, was the most effective chart when it came to identifying clinically important risk increases in SGA infants.

Humanin (HN) and glucose transporter 8 (GLUT8) in pregnancies complicated by intrauterine growth restriction

Background

Intrauterine growth restriction (IUGR) results from a lack of nutrients transferred to the developing fetus, particularly oxygen and glucose. Increased expression of the cytoprotective mitochondrial peptide, humanin (HN), and the glucose transporter 8, GLUT8, has been reported under conditions of hypoxic stress. However, the presence and cellular localization of HN and GLUT8 in IUGR-related placental pathology remain unexplored. Thus, we undertook this study to investigate placental expression of HN and GLUT8 in IUGR-affected versus normal pregnancies.

Results

We found 1) increased HN expression in human IUGR-affected pregnancies on the maternal aspect of the placenta (extravillous trophoblastic (EVT) cytoplasm) compared to control (i.e. appropriate for gestational age) pregnancies, and a concomitant increase in GLUT8 expression in the same compartment, 2) HN and GLUT8 showed a protein-protein interaction by co-immunoprecipitation, 3) elevated HN and GLUT8 levels in vitro under simulated hypoxia in human EVT cells, HTR8/SVneo, and 4) increased HN expression but attenuated GLUT8 expression in vitro under serum deprivation in HTR8/SVneo cells.

Conclusions

There was elevated HN expression with cytoplasmic localization to EVTs on the maternal aspect of the human placenta affected by IUGR, also associated with increased GLUT8 expression. We found that while hypoxia increased both HN and GLUT8, serum deprivation increased HN expression alone. Also, a protein-protein interaction between HN and GLUT8 suggests that their interaction may fulfill a biologic role that requires interdependency. Future investigations delineating molecular interactions between these proteins are required to fully uncover their role in IUGR-affected pregnancies.

Multidisciplinary consensus on screening for, diagnosis and management of fetal growth restriction in the Netherlands

BACKGROUND

Screening for, diagnosis and management of intrauterine growth restriction (IUGR) is often performed in multidisciplinary collaboration. However, variation in screening methods, diagnosis and management of IUGR may lead to confusion. In the Netherlands two monodisciplinary guidelines on IUGR do not fully align. To facilitate effective collaboration between different professionals in perinatal care, we undertook a Delphi study with uniform recommendations as our primary result, focusing on issues that are not aligned or for which specifications are lacking in the current guidelines.

METHODS

We conducted a Delphi study in three rounds. A purposively sampled selection of 56 panellists participated: 27 representing midwife-led care and 29 obstetrician-led care. Consensus was defined as agreement between the professional groups on the same answer and among at least 70% of the panellists within groups.

RESULTS

Per round 51 or 52 (91% - 93%) panellists responded. This has led to consensus on 27 issues, leading to four consensus based recommendations on screening for IUGR in midwife-led care and eight consensus based recommendations on diagnosis and eight on management in obstetrician-led care. The multidisciplinary project group decided on four additional recommendations as no consensus was reached by the panel. No recommendations could be made about induction of labour versus expectant monitoring, nor about the choice for a primary caesarean section.

CONCLUSIONS

We reached consensus on recommendations for care for IUGR within a multidisciplinary panel. These will be implemented in a study on the effectiveness and cost-effectiveness of routine third trimester ultrasound for monitoring fetal growth. Research is needed to evaluate the effects of implementation of these recommendations on perinatal outcomes.

TRIAL REGISTRATION

NTR4367 .

The clinical significance of an estimated fetal weight below the 10th percentile: a comparison of outcomes of <5th vs 5th-9th percentile

BACKGROUND

The association between small-for-gestational-age (birthweight <10th percentile for gestational age) and neonatal morbidity is well established. Yet, there is a paucity of data on the relationship between suspected small for gestational age (sonographic-estimated fetal weight <10th percentile) at 2 thresholds and subsequent neonatal morbidity.

OBJECTIVE

The objective of this study was to determine the relationship between sonographic-estimated fetal weight <5th percentile vs 5-9th percentile and neonatal morbidity.

STUDY DESIGN

This retrospective study involved 5 centers and included nonanomalous, singletons with sonographic-estimated fetal weight <10th percentile for gestational age who delivered from 2009-2012. Composite neonatal morbidity included respiratory distress syndrome, proven sepsis, intraventricular hemorrhage grade III or IV, necrotizing enterocolitis, thrombocytopenia, seizures, or death. Odd ratios were adjusted for center, maternal age, race, body mass index at first visit, smoking status, use of alcohol, use of drugs, and neonatal gender.

RESULTS

Of 834 women with suspected small-for-gestational-age fetuses, 513 (62%) had sonographic-estimated fetal weight <5th percentile, and 321 (38%) had sonographic-estimated fetal weight of 5-9th percentile for gestational age. At delivery, 81% of women with a suspected small-for-gestational-age fetus had a confirmed small-for-gestational-age fetus. In the group with a sonographic-estimated fetal weight <5th percentile, 59% of neonates had birthweight <5th percentile; in the group with a sonographic-estimated fetal weight 5-9th percentile, 41% had birthweight <5th percentile, and 36% had birthweight at 5-9th percentile. Neonatal intensive care unit admission differed significantly for those fetuses at <5th percentile (29%) compared with those fetuses at 5-9th percentile (15%; P<.001). The composite neonatal morbidity among the sonographic-estimated fetal weight <5th percentile group was higher than the sonographic-estimated fetal weight of 5-9th percentile group (31% vs 13%; adjusted odds ratio, 2.41; 95% confidence interval, 1.53-3.80). Similar findings were noted when the analysis was limited to sonographic-estimated fetal weight within 28 days of delivery (adjusted odds ratio, 2.22; 95% confidence interval, 1.34-3.67).

CONCLUSION

Eight of 10 suspected small-for-gestational-age fetuses had birthweight <10th percentile for gestational age; the prediction of actual birthweight was more accurate in the <5th percentile group. Neonates with sonographic-estimated fetal weight of <5th percentile were more likely to be admitted to the neonatal intensive care unit and have complications than were those neonates with sonographic-estimated fetal weight of 5-9th percentile.

Diffusion-weighted magnetic resonance imaging of the fetal brain in intrauterine growth restriction

OBJECTIVE

Diffusion-weighted magnetic resonance imaging (DWI) is a sensitive method for assessing brain maturation and detecting brain lesions, providing apparent diffusion coefficient (ADC) values as a measure of water diffusion. Abnormal ADC values are seen in ischemic brain lesions, such as those associated with acute or chronic hypoxia. The aim of this study was to assess whether ADC values in the fetal brain were different in fetuses with severe intrauterine growth restriction (IUGR) compared with normal controls.

METHODS

Brain magnetic resonance imaging (MRI) with single-shot axial DWI (b = 0 and b = 700 s/mm² ) was performed in 30 fetuses with severe IUGR (estimated fetal weight < 3^rd centile with absent or reversed umbilical artery Doppler flow) and in 24 normal controls of similar gestational age. Brain morphology and biometry were analyzed. ADC values were measured in frontal and occipital white matter, centrum semiovale, thalami, cerebellar hemisphere and pons. Frontal-occipital and frontal-cerebellar ADC ratios were calculated, and values were compared between IUGR fetuses and controls.

RESULTS

There was no difference in gestational age at MRI between IUGR and control fetuses (IUGR, 30.2 ± 1.6 weeks vs controls, 30.7 ± 1.4 weeks). Fetal brain morphology and signals were normal in all fetuses. Brain dimensions (supratentorial ± infratentorial) were decreased (Z-score, < -2) in 20 (66.7%) IUGR fetuses. Compared with controls, IUGR fetuses had significantly lower ADC values in frontal white matter (1.97 ± 0.23 vs 2.17 ± 0.22 × 10^-3 mm² /s; P < 0.0001), thalami (1.04 ± 0.15 vs 1.13 ± 0.10 ×10^-3 mm² /s; P = 0.0002), centrum semiovale (1.86 ± 0.22 vs 1.97 ± 0.23 ×10^-3 mm² /s; P = 0.01) and pons (0.85 ± 0.19 vs 0.94 ± 0.12 ×10^-3 mm² /s; P = 0.043). IUGR fetuses had a lower frontal-occipital ADC ratio than did normal fetuses (1.00 ± 0.11 vs 1.08 ± 0.05; P = 0.003).

CONCLUSIONS

ADC values in IUGR fetuses were significantly lower than in normal controls in the frontal white matter, thalami, centrum semiovale and pons, suggesting abnormal maturation in these regions. However, the prognostic value of these ADC changes is still unknown. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Maternal and perinatal characteristics of small-for-gestational-age newborns: Ten-year experience of a single center

OBJECTIVE

To analyze the maternal and perinatal characteristics of small-for-gestational-age (SGA) newborns compared with appropriate-for-gestational-age (AGA) newborns in singleton pregnancies managed at our hospital between January 2006 and December 2015.

MATERIAL AND METHODS

The study (n=456) and control (n=4925) groups included pregnancies resulting in SGA and AGA newborns, respectively. Additionally, two SGA subgroups were defined according to abnormal (n=34) and normal (n=57) Doppler findings. Maternal demographic features; intracytoplasmic sperm injection (ICSI) pregnancies; gestational age at delivery; birth weight; major congenital anomalies, karyotype abnormalities, and genetic syndromes; maternal and obstetric problems such as hypertensive disorders, diabetes, oligohydramnios, preterm birth; admission to the neonatal intensive care unit (NICU), and perinatal mortality were recorded, and the two groups were compared with respect to these parameters.

RESULTS

Mean maternal age, parity, gestational age at delivery, and birthweight were significantly lower; the frequencies of ICSI pregnancies, hypertensive disorders, oligohydramnios, preterm delivery, major congenital anomalies, karyotype abnormalities and genetic syndromes, admission to the NICU and perinatal mortality were significantly higher in the study group (p<0.05). None of the study parameters were significantly different between the two SGA subgroups (p>0.05).

CONCLUSION

The association of SGA with ICSI pregnancies, hypertensive disorders, oligohydramnios, preterm delivery, congenital/chromosomal anomalies, NICU admission and perinatal mortality may be important in perinatal care. Clinical suspicion of SGA necessitates appropriate monitorization and management. Although obstetric outcomes were not significantly different between the two SGA subgroups with abnormal and normal Doppler findings in this study, this finding must be evaluated with caution due to the small sizes.

An epigenetic clock for gestational age at birth based on blood methylation data

Background

Gestational age is often used as a proxy for developmental maturity by clinicians and researchers alike. DNA methylation has previously been shown to be associated with age and has been used to accurately estimate chronological age in children and adults. In the current study, we examine whether DNA methylation in cord blood can be used to estimate gestational age at birth.

Results

We find that gestational age can be accurately estimated from DNA methylation of neonatal cord blood and blood spot samples. We calculate a DNA methylation gestational age using 148 CpG sites selected through elastic net regression in six training datasets. We evaluate predictive accuracy in nine testing datasets and find that the accuracy of the DNA methylation gestational age is consistent with that of gestational age estimates based on established methods, such as ultrasound. We also find that an increased DNA methylation gestational age relative to clinical gestational age is associated with birthweight independent of gestational age, sex, and ancestry.

Conclusions

DNA methylation can be used to accurately estimate gestational age at or near birth and may provide additional information relevant to developmental stage. Further studies of this predictor are warranted to determine its utility in clinical settings and for research purposes. When clinical estimates are available this measure may increase accuracy in the testing of hypotheses related to developmental age and other early life circumstances.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-016-1068-z) contains supplementary material, which is available to authorized users.

Searching for the definition of macrosomia through an outcome-based approach in low- and middle-income countries: a secondary analysis of the WHO Global Survey in Africa, Asia and Latin America

Background

No consensus definition of macrosomia currently exists among researchers and obstetricians. We aimed to identify a definition of macrosomia that is more predictive of maternal and perinatal mortality and morbidity in low- and middle-income countries.

Methods

We conducted a secondary data analysis using WHO Global Survey on Maternal and Perinatal Health data on Africa and Latin America from 2004 to 2005 and Asia from 2007 to 2008. We compared adverse outcomes, which were assessed by the composite maternal mortality and morbidity index (MMMI) and perinatal mortality and morbidity index (PMMI) in subgroups with birthweight (3000–3499 g [reference group], 3500–3999 g, 4000–4099 g, 4100–4199 g, 4200–4299 g, 4300–4399 g, 4400–4499 g, 4500–4999 g) or country-specific birthweight percentile for gestational age (50^th–74^th percentile [reference group], 75^th–89^th, 90^th–94^th, 95^th–96^th, and ≥97^th percentile). Two-level logistic regression models were used to estimate odds ratios of MMMI and PMMI.

Results

A total of 246,659 singleton term births from 363 facilities in 23 low- and middle-income countries were included. Adjusted odds ratios (aORs) for intrapartum caesarean sections exceeded 2.0 when birthweight was greater than 4000 g (2 · 00 [95 % CI: 1 · 68, 2 · 39], 2 · 42 [95 % CI: 2 · 02, 2 · 89], 2 · 01 [95 % CI: 1 · 74, 2 · 33] in Africa, Asia and Latin America, respectively). aORs of MMMI reached 2.0 when birthweight was greater than 4000 g, 4500 g in Asia and Africa, respectively. aORs of PMMI approached to 2.0 (1 · 78 [95 % CI: 1 · 16, 2 · 74]) when birthweight was greater than 4500 g in Latin America. When birthweight was at the 90^th percentile or higher, aORs of MMMI and PMMI increased, but none exceeded 2.0.

Conclusions

The population-specific definition of macrosomia using birthweight cut-off points irrespective of gestational age (4500 g in Africa and Latin America, 4000 g in Asia) is more predictive of maternal and perinatal adverse outcomes, and simpler to apply compared to the definition based on birthweight percentile for a given gestational age.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-015-0765-z) contains supplementary material, which is available to authorized users.

Term breech deliveries in the Netherlands: did the increased cesarean rate affect neonatal outcome? A population-based cohort study

OBJECTIVE

The aim of this study was to evaluate the effect of the increased cesarean rate for term breech presentation on neonatal outcome. We also investigated whether the clinical case selection for vaginal delivery applied by Dutch obstetricians led to an optimization of neonatal outcome, or whether there is still room for improvement in terms of perinatal outcome.

DESIGN

Retrospective cohort.

SETTING

The Netherlands.

POPULATION

Singleton term breech deliveries from 37+0 to 41+6 weeks, excluding fetuses with congenital malformations or antenatal death.

METHOD

We used data from the Dutch national perinatal registry from 1999 up to 2007.

MAIN OUTCOME MEASURES

Perinatal mortality and morbidity.

RESULTS

We studied 58,320 women with a term breech delivery. There was an increase in the elective cesarean rate (from 24 to 60%). As a consequence, overall perinatal mortality decreased [1.3 0/00 vs. 0.7 0/00;odds ratio 0.51 (95% confidence interval 0.28–0.93)], whereas it remained stable in the planned vaginal birth group [1.7 0/00 vs. 1.6 0/00; odds ratio 0.96(95% confidence interval 0.52–1.76)]. The number of cesareans done to prevent one perinatal death was 338.

CONCLUSIONS

Adjustment of the national guidelines after publication of the Term Breech Trial resulted in a shift towards elective cesarean and a decrease of perinatal mortality and morbidity among women delivering a child in breech at term. Still, 40% of these women attempt vaginal birth. The relative safety of an elective cesarean should be weighed against the consequences of a scarred uterus in future pregnancies.

Searching for the definition of macrosomia through an outcome-based approach

Background

Macrosomia has been defined in various ways by obstetricians and researchers. The purpose of the present study was to search for a definition of macrosomia through an outcome-based approach.

Methods

In a study of 30,831,694 singleton term live births and 38,053 stillbirths in the U.S. Linked Birth-Infant Death Cohort datasets (1995–2004), we compared the occurrence of stillbirth, neonatal death, and 5-min Apgar score less than four in subgroups of birthweight (4000–4099 g, 4100–4199 g, 4200–4299 g, 4300–4399 g, 4400–4499 g, 4500–4999 g vs. reference group 3500–4000 g) and birthweight percentile for gestational age (90^th–94^th percentile, 95^th-96^th, and ≥97^th percentile, vs. reference group 75^th–90^th percentile).

Results

There was no significant increase in adverse perinatal outcomes until birthweight exceeded the 97^th percentile. Weight-specific odds ratios (ORs) elevated substantially to 2 when birthweight exceeded 4500 g in Whites. In Blacks and Hispanics, the aORs exceeded 2 for 5-min Apgar less than four when birthweight exceeded 4300 g. For vaginal deliveries, the aORs of perinatal morbidity and mortality were larger for most of the subgroups, but the patterns remained the same.

Conclusions

A birthweight greater than 4500 g in Whites, or 4300 g in Blacks and Hispanics regardless of gestational age is the optimal threshold to define macrosomia. A birthweight greater than the 97^th percentile for a given gestational age, irrespective of race is also reasonable to define macrosomia. The former may be more clinically useful and simpler to apply.

Optimal risk assessment of small-for-gestational-age fetuses using 31-34-week biometry in a low-risk population

OBJECTIVE

To compare the performance of traditional growth charts for estimated fetal weight (EFW) and a validated pragmatic probabilistic approach using biometry at 31-34 weeks' gestation to screen for late pregnancy small-for-gestational age (SGA) fetuses in a low-risk population.

METHODS

Records of ultrasound biometry at 31-34 weeks were reviewed in 7755 consecutive low-risk women between 2002 and 2011. Fetal malformations, Doppler anomalies and preterm delivery before 37 weeks were excluded. SGA was defined by various percentile cut-offs of birth weight. The probability of SGA was modeled as a function of Z-scores of femur length, abdominal circumference and head circumference. The model was validated on a second independent dataset of 1725 pregnancies from a different screening unit. The screening performance of this probabilistic approach was compared with those of traditional EFW growth charts. The additional value of factoring in maternal characteristics was also ascertained.

RESULTS

Using national birth-weight charts, the proportions of newborns at 37-42 weeks with birth weight<3(rd) , <5(th) and<10(th) centiles were 3%, 6% and 12%, respectively, and there was a 2% rate of birth weight<2500 g. For a 10% false-positive rate, a direct probabilistic approach yielded a 51% detection rate of neonates with birth weight<10(th) centile, compared to the 32% and 48% detection rates given by the 10(th) centile cut-off of two reference charts for EFW. Adding maternal characteristics significantly improved detection rate by 2% to 53%.

CONCLUSIONS

The suggested validated approach to screening for late SGA fetuses outperforms traditional approaches using growth charts. By adding maternal characteristics, this screening method offers a favorable alternative to customized charts.

The implications of diagnosis of small for gestational age fetuses using European and South Asian growth charts: an outcome-based comparative study

The antenatal condition of small for gestational age (SGA) is significantly associated with perinatal morbidity and mortality and it is known that there are significant differences in birth weight and fetal size among different populations. The aim of our study was to assess the impact on outcomes of the diagnosis of SGA according to Bangladeshi and European antenatal growth charts in Sri Lankan population. The estimated fetal weight before delivery was retrospectively reviewed according to Bangladeshi and European growth references. Three groups were identified: Group 1-SGA according to Bangladeshi growth chart; Group 2-SGA according to European growth chart but not having SGA according to Bangladeshi growth chart; Group 3-No SGA according to both charts. There was a difference in prevalence of SGA between Bangladeshi and European growth charts: 12.7% and 51.7%, respectively. There were statistically significant higher rates in emergency cesarean section, fetal distress in labour, and intrauterine death (P < 0.001) in Group 1 compared with Group, 2 and 3. No differences of outcomes occurred between Groups 2 and 3. Our study demonstrated that only cases diagnosed as SGA according to population-based growth charts are at risk of adverse outcome. The use of inappropriate prenatal growth charts might lead to misdiagnosis and potential unnecessary interventions.

Placental glucose transporter 3 (GLUT3) is up-regulated in human pregnancies complicated by late-onset intrauterine growth restriction

INTRODUCTION

Transport of glucose from maternal blood across the placental trophoblastic tissue barrier is critical to sustain fetal growth. The mechanism by which GLUTs are regulated in trophoblasts in response to ischemic hypoxia encountered with intrauterine growth restriction (IUGR) has not been suitably investigated.

OBJECTIVE

To investigate placental expression of GLUT1, GLUT3 and GLUT4 and possible mechanisms of GLUT regulation in idiopathic IUGR.

METHODS

We analyzed clinical, biochemical and histological data from placentas collected from women affected by idiopathic full-term IUGR (n = 10) and gestational age-matched healthy controls (n = 10).

RESULTS

We found increased GLUT3 protein expression in the trophoblast (cytotrophoblast greater than syncytiotrophoblast) on the maternal aspect of the placenta in IUGR compared to normal placenta, but no differences in GLUT1 or GLUT4 were found. No differential methylation of the GLUT3 promoter between normal and IUGR placentas was observed. Increased GLUT3 expression was associated with an increased nuclear concentration of HIF-1α, suggesting hypoxia may play a role in the up-regulation of GLUT3.

DISCUSSION

Further studies are needed to elucidate whether increased GLUT3 expression in IUGR is a marker for defective villous maturation or an adaptive response of the trophoblast in response to chronic hypoxia.

CONCLUSIONS

Patients with IUGR have increased trophoblast expression of GLUT3, as found under the low-oxygen conditions of the first trimester.

Application of a global reference for fetal-weight and birthweight percentiles in predicting infant mortality

OBJECTIVE

To determine whether the recently published A global reference for fetal-weight and birthweight percentiles (Global Reference) improves small- (SGA), appropriate- (AGA), and large-for-gestational-age (LGA) definitions in predicting infant mortality.

DESIGN

Population-based cohort study.

SETTING

The US Linked Livebirth and Infant Death records between 1995 and 2004.

POPULATION

Singleton births with birthweight >500 g born at 24-41 weeks of gestation.

METHODS

We compared infant mortality rates of SGA, AGA, and LGA infants classified by three different references: the Global Reference; a commonly used birthweight reference; and Hadlock's ultrasound reference.

MAIN OUTCOME MEASURES

Infant mortality rates.

RESULTS

Among 33 997 719 eligible liveborn singleton births, 25% of preterm and 9% of term infants were classified differently for SGA, AGA, and LGA by the Global Reference and the birthweight reference. The Global Reference indicated higher mortality rates in preterm SGA and preterm LGA infants than the birthweight reference. The mortality rate was considerably higher in infants classified as preterm SGA by the Global Reference but not by the birthweight reference, compared with the corresponding infants classified by the birthweight reference but not by the Global Reference (105.7 versus 12.9 per 1000, RR 8.17, 95% CI 7.38-9.06). Yet, the differences in mortality rates were much smaller in term infants than in preterm infants. Black infants had a particularly higher mortality rate than other races in AGA and LGA preterm and term infants.

CONCLUSIONS

In respect to the commonly used birthweight reference, the Global Reference increases the identification of infant deaths by improved classification of abnormal newborn size at birth, and these advantages were more obvious in preterm than in term infants.

Effects on (neuro)developmental and behavioral outcome at 2 years of age of induced labor compared with expectant management in intrauterine growth-restricted infants: long-term outcomes of the DIGITAT trial

OBJECTIVE

We sought to study long-term (neuro)developmental and behavioral outcome of pregnancies complicated by intrauterine growth restriction at term in relation to induction of labor or an expectant management.

STUDY DESIGN

Parents of 2-year-old children included in the Disproportionate Intrauterine Growth Intervention Trial at Term (DIGITAT) answered the Ages and Stages Questionnaire (ASQ) and Child Behavior Checklist (CBCL).

RESULTS

We approached 582 (89.5%) of 650 parents. The response rate was 50%. Of these children, 27% had an abnormal score on the ASQ and 13% on the CBCL. Results of the ASQ and the CBCL for the 2 policies were comparable. Low birthweight, positive Morbidity Assessment Index score, and admission to intermediate care increased the risk of an abnormal outcome of the ASQ. This effect was not seen for the CBCL.

CONCLUSION

In women with intrauterine growth restriction at term, neither a policy of induction of labor nor expectant management affect developmental and behavioral outcome when compared to expectant management.

Neonatal morbidity after induction vs expectant monitoring in intrauterine growth restriction at term: a subanalysis of the DIGITAT RCT

OBJECTIVE

The Disproportionate Intrauterine Growth Intervention Trial at Term (DIGITAT) compared induction of labor and expectant management in suspected intrauterine growth restriction (IUGR) at term. In this subanalysis, we report neonatal morbidity between the policies based on the Morbidity Assessment Index for Newborns (MAIN).

STUDY DESIGN

We used data from the DIGITAT. For each neonate, we calculated the MAIN score, a validated outcome scale.

RESULTS

There were no differences in mean MAIN scores or in MAIN morbidity categories. We found that neonatal admissions are lower after 38 weeks' gestational age compared with 36 and 37 weeks in both groups.

CONCLUSION

The incidence of neonatal morbidity in IUGR at term is comparable and relatively mild either after induction or after an expectant policy. However, neonatal admissions are lower after 38 weeks of pregnancy, so if induction to preempt possible stillbirth is considered, it is reasonable to delay until 38 weeks, provided watchful monitoring.

Neurologic outcomes at school age in very preterm infants born with severe or mild growth restriction

OBJECTIVE

To determine whether mild and severe growth restriction at birth among preterm infants is associated with neonatal mortality and cerebral palsy and cognitive performance at 5 years of age and school performance at 8 years of age.

METHODS

All 2846 live births between 24 and 32 weeks' gestation from 9 regions in France in 1997 were included in a prospective observational study (the EPIPAGE [Étude Epidémiologique sur les Petits Ages Gestationnels] study) and followed until 8 years of age. Infants were classified as "small-for-gestational-age" (SGA) if their birth weight for gestational age was at the <10th centile, "mildly-small-for-gestational-age" (M-SGA) if birth weight was at the ≥ 10th centile and <20th centile, and "appropriate-for-gestational-age" (AGA) if birth weight was at the ≥ 20th centile.

RESULTS

Among the children born between 24 and 28 weeks' gestation, the mortality rate increased from 30% in the AGA group to 42% in the M-SGA group and to 62% in the SGA group (P < .01). Birth weight was not significantly associated with any cognitive, behavioral, or motor outcomes at the age of 5 or any school performance outcomes at 8 years. For the children born between 29 and 32 weeks' gestation, SGA children had a higher risk for mortality (adjusted odds ratio [aOR]: 2.79 [95% confidence interval (CI): 1.50-5.20]), minor cognitive difficulties (aOR: 1.73 [95% CI: 1.12-2.69]), inattention-hyperactivity symptoms (aOR: 1.78 [95% CI: 1.10-2.89]), and school difficulties (aOR: 1.74 [1.07-2.82]) compared with AGA children. Being born M-SGA was associated with an increased risk for minor cognitive difficulties (aOR: 1.87 [95% CI: 1.24-2.82]) and behavioral difficulties (aOR: 1.66 [95% CI: 1.04-2.62]).

CONCLUSIONS

In preterm children, growth restriction was associated with mortality, cognitive and behavioral outcomes, as well as school difficulties.

Aberrant fetal growth and early, late, and postneonatal mortality: an analysis of Milwaukee births, 1996-2007

OBJECTIVE

The objective of the study was to ascertain the association between fetal growth (small- [SGA], appropriate- [AGA], and large-for-gestational-age [LGA]) and early, late, and postneonatal mortality.

STUDY DESIGN

Birth certificate data for nonanomalous singletons, delivered from 1996 to 2007, were obtained for Milwaukee residents. Multivariate logistic regression analyses, adjusted for 19 covariates, determined the association between fetal growth and mortality.

RESULTS

Among the 123,383 live births, SGA was 57% higher than LGA (11% vs 7%). The infant mortality rate for SGA was 11.0, AGA, 5.3, and LGA, 2.7/1000 live births. SGA was a significant risk factor for early (adjusted odds ratio, 2.66) and late (2.06) but not postneonatal mortality. The adjusted risk of mortality for LGA was not significantly different from AGA. Over 12 years, 3 types of mortality for aberrant fetal growth did not change significantly.

CONCLUSION

In the city of Milwaukee, aberrant fetal growth was variably associated with early, late, and postneonatal mortality.

Induction versus expectant monitoring for intrauterine growth restriction at term: randomised equivalence trial (DIGITAT)

OBJECTIVE

To compare the effect of induction of labour with a policy of expectant monitoring for intrauterine growth restriction near term.

DESIGN

Multicentre randomised equivalence trial (the Disproportionate Intrauterine Growth Intervention Trial At Term (DIGITAT)).

SETTING

Eight academic and 44 non-academic hospitals in the Netherlands between November 2004 and November 2008.

PARTICIPANTS

Pregnant women who had a singleton pregnancy beyond 36+0 weeks' gestation with suspected intrauterine growth restriction.

INTERVENTIONS

Induction of labour or expectant monitoring.

MAIN OUTCOME MEASURES

The primary outcome was a composite measure of adverse neonatal outcome, defined as death before hospital discharge, five minute Apgar score of less than 7, umbilical artery pH of less than 7.05, or admission to the intensive care unit. Operative delivery (vaginal instrumental delivery or caesarean section) was a secondary outcome. Analysis was by intention to treat, with confidence intervals calculated for the differences in percentages or means.

RESULTS

321 pregnant women were randomly allocated to induction and 329 to expectant monitoring. Induction group infants were delivered 10 days earlier (mean difference -9.9 days, 95% CI -11.3 to -8.6) and weighed 130 g less (mean difference -130 g, 95% CI -188 g to -71 g) than babies in the expectant monitoring group. A total of 17 (5.3%) infants in the induction group experienced the composite adverse neonatal outcome, compared with 20 (6.1%) in the expectant monitoring group (difference -0.8%, 95% CI -4.3% to 3.2%). Caesarean sections were performed on 45 (14.0%) mothers in the induction group and 45 (13.7%) in the expectant monitoring group (difference 0.3%, 95% CI -5.0% to 5.6%).

CONCLUSIONS

In women with suspected intrauterine growth restriction at term, we found no important differences in adverse outcomes between induction of labour and expectant monitoring. Patients who are keen on non-intervention can safely choose expectant management with intensive maternal and fetal monitoring; however, it is rational to choose induction to prevent possible neonatal morbidity and stillbirth.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial number ISRCTN10363217.

Maternal low-level lead exposure and fetal growth

BACKGROUND

Limited epidemiologic studies have examined the association between maternal low-level lead exposure [blood lead (PbB) < 10 µg/dL] and fetal growth.

OBJECTIVE

We examined whether maternal low-level lead exposure is associated with decreased fetal growth.

METHODS

We linked New York State Heavy Metals Registry records of women who had PbB measurements with birth certificates to identify 43,288 mother-infant pairs in upstate New York in a retrospective cohort study from 2003 through 2005. We used multiple linear regression with fractional polynomials and logistic regression to relate birth weight, preterm delivery, and small for gestational age to PbB levels, adjusting for potential confounders. We used a closed-test procedure to identify the best fractional polynomials for PbB among 44 combinations.

RESULTS

We found a statistically significant association between PbB (square root transformed) and birth weight. Relative to 0 µg/dL, PbBs of 5 and 10 µg/dL were associated with an average of 61-g and 87-g decrease in birth weight, respectively. The adjusted odds ratio for PbBs between 3.1 and 9.9 µg/dL (highest quartile) was 1.04 [95% confidence interval (CI), 0.89-1.22] for preterm delivery and 1.07 (95% CI, 0.93-1.23) for small for gestational age, relative to PbBs ≤ 1 µg/dL (lowest quartile). No clear dose-response trends were evident when all of the quartiles were assessed.

CONCLUSIONS

Low-level PbB was associated with a small risk of decreased birth weight with a supralinear dose-response relationship, but was not related to preterm birth or small for gestational age. The results have important implications regarding maternal PbB.

Optimal birth weight percentile cut-offs in defining small- or large-for-gestational-age

AIMS

It remains questionable what birth weight for gestational age percentile cut-offs should be used in defining clinically important poor or excessive foetal growth. We aimed to evaluate the optimal birth weight percentile cut-offs for defining small- or large-for-gestational-age (SGA or LGA).

METHODS

In a birth cohort-based analysis of 17 979 120 non-malformation singleton live births, U.S. 1995-2001, we assessed the optimal birth weight percentile cut-offs for defining SGA and LGA. The 25th-75th percentile group served as the reference. Primary outcomes are the risk ratios (RR) of neonatal death and low 5-min Apgar score (<4) comparing SGA or LGA versus the reference group. More than 2-fold risk elevations were considered clinically significant.

RESULTS

The 15th birth weight cut-off already identified SGA infants at more than 2-fold risk of neonatal death at pre-term, term or post-term, except for extremely pre-term births <28 weeks (continuous risk reductions over increasing birth weight percentiles). LGA was associated with a reduced risk of low 5-min Apgar score at pre-term, but an elevated risk at term and post-term. The 97th cut-off identified LGA infants at 2-fold risk of low 5-min Apgar at term.

CONCLUSION

The commonly used 10th and 90th birth weight percentile cut-offs for defining SGA and LGA respectively seem largely arbitrary. The 15th and 97th percentiles may be the optimal cut-offs to define SGA and LGA respectively.

Distinguishing pathological from constitutional small for gestational age births in population-based studies

BACKGROUND

Small for gestational age (SGA) can occur following a pathological process or may represent constitutionally small fetuses. However, distinguishing these processes is often difficult, especially in large studies, where the term SGA is often used as a proxy for restricted fetal growth. Since biologic variation in fetal size is largely a third trimester phenomenon, we hypothesized that the definition of SGA at term may include a sizeable proportion of constitutionally small fetuses. In contrast, since biologic variation in fetal size is not fully expressed in (early) preterm gestations, it is plausible that SGA in early preterm gestations would comprise a large proportion of growth restricted fetuses.

AIM

We compared mortality and morbidity rates between SGA and appropriate for gestational age (AGA) babies.

SUBJECTS

A population-based study of over 19million non-malformed, singleton births (1995-04) in the United States was performed. Gestational age (24-44weeks) was based on a clinical estimate. SGA and AGA were defined as sex-specific birthweight <10th and 25-74th centiles, respectively, for gestational age. All analyses were adjusted for a variety of confounding factors.

OUTCOME MEASURES

Excess mortality risk in SGA and AGA babies.

RESULTS

On an additive scale, stillbirth and neonatal mortality rates were higher at every preterm gestation among SGA than AGA births, and similar at term gestations. An inverse relationship between gestational age and excess deaths between SGA and AGA babies delivered at <37weeks was evident.

CONCLUSIONS

In early preterm gestations, the definition of SGA may well be justified as a proxy for IUGR. In contrast, SGA babies that are delivered at term are likely to be constitutionally small.

Leptin in first trimester pregnancy serum: no reduction associated with small-for-gestational-age infants

Leptin is an adipocytokine that is also synthesized by the placenta. Leptin and its receptor, which is also expressed by the placenta, are believed to play an auto- and paracrine role in trophoblast invasion and placental development. The leptin concentration in first trimester maternal serum and its relation to fetal growth disturbances were examined in this study. The study is a case-control study with 36 small-for-gestational-age (SGA) (<5th percentile) pregnancies and 108 appropriate-for-gestational-age (AGA) (> or =5th percentile) pregnancies. The groups were matched by maternal age, gestational age and body mass index (BMI). All were non-smokers. Leptin was measured in maternal serum in weeks 8-13 and was normalized for BMI with concentrations expressed as multiples of the median for the actual BMI. It was found that maternal serum leptin increased strongly (r = 0.7, P < 10(-4))with maternal BMI. There was no significant difference in maternal serum leptin concentrations between SGA and AGA pregnancies. In conclusion, SGA pregnancies are not associated with a lower maternal serum leptin concentration in first trimester. The maternal serum leptin concentration is largely determined by maternal BMI. Variation in the leptin concentration in maternal serum in first trimester does not seem to be associated with impaired fetal growth.

An outcome-based approach for the creation of fetal growth standards: do singletons and twins need separate standards?

Contemporary fetal growth standards are created by using theoretical properties (percentiles) of birth weight (for gestational age) distributions. The authors used a clinically relevant, outcome-based methodology to determine if separate fetal growth standards are required for singletons and twins. All singleton and twin livebirths between 36 and 42 weeks’ gestation in the United States (1995–2002) were included, after exclusions for missing information and other factors (n = 17,811,922). A birth weight range was identified, at each gestational age, over which serious neonatal morbidity and neonatal mortality rates were lowest. Among singleton males at 40 weeks, serious neonatal morbidity/mortality rates were lowest between 3,012 g (95% confidence interval (CI): 3,008, 3,018) and 3,978 g (95% CI: 3,976, 3,980). The low end of this optimal birth weight range for females was 37 g (95% CI: 21, 53) less. The low optimal birth weight was 152 g (95% CI: 121, 183) less for twins compared with singletons. No differences were observed in low optimal birth weight by period (1999–2002 vs. 1995–1998), but small differences were observed for maternal education, race, parity, age, and smoking status. Patterns of birth weight-specific serious neonatal morbidity/neonatal mortality support the need for plurality-specific fetal growth standards.

Fetal growth restriction: a modern approach

PURPOSE OF REVIEW

Fetal growth restriction is a complicated perinatal condition, with multiple causes. It shares common pathophysiologies with other important disorders, such as preeclampsia and abruption. As a group, these conditions associated with ischemic placental disease are responsible for a large percentage of indicated preterm births. The ability to accurately predict, diagnose and manage these pregnancies has significant and far-reaching implications, including potential effects on long-term adult health.

RECENT FINDINGS

Placental ischemia is the most common cause of fetal growth restriction. Alterations in placental development are being linked to various angiogenic mediators, which may be of future use in early risk-determination. Until then, the use of ultrasound to accurately diagnose fetal growth restriction and time delivery is the mainstay of management. Research in this area has revealed some commonalities in the deterioration of the growth restricted fetus, but has also indicated that not every affected fetus will follow the same progression in Doppler and other wellbeing parameters. Most importantly, gestational age at delivery is consistently being documented as a critical factor in perinatal morbidity and mortality.

SUMMARY

Fetal growth restriction is a late manifestation of early abnormal placental development. Once abnormal Doppler velocimetry is present, surveillance and timing of delivery should be based on the antepartum test results and on the gestational age.

Circulating and placental endoglin concentrations in pregnancies complicated by intrauterine growth restriction and preeclampsia

Inadequate trophoblast invasion and spiral artery remodeling leading to poor placental perfusion and hypoxia are believed to underlie preeclampsia (PE) and intrauterine growth restriction (IUGR). Recent studies implicate increased circulating endoglin as a contributor to the pathogenesis of PE. The objective of this study was to determine whether placental and circulating endoglin concentrations are altered in pregnancies complicated by intrauterine growth restricted (IUGR) infants and to address the role of hypoxia on the regulation of placental endoglin. We analyzed 10 placentas each from normal pregnant (NP), PE, and IUGR subjects. Endoglin levels were 2.5-fold higher in preeclamptic placentas compared to NP (15.4+/-2.6 versus 5.7+/-1.0, p<0.01). In contrast, endoglin levels were similar in NP and IUGR placentas (5.7+/-1.0 vs 5.9+/-1.1, p=NS). Placentas from pregnancies with both PE and IUGR exhibited endoglin levels comparable to the PE group and significantly different from normotensive pregnancies with and without IUGR pregnancies (mean 14.9+/-4.0, n=9, p=0.013). Soluble endoglin concentrations in maternal plasma were comparable in NP and IUGR, but higher in women with PE (n=10 per group, p<0.05). Despite a 2-fold increase in hypoxia inducible factor, HIF-1alpha, we did not observe endoglin upregulation in NP, PE, or IUGR placental villous explants exposed to hypoxia (2% oxygen). In contrast to PE, placental or circulating endoglin is not increased in normotensive women delivering small, asymmetrically grown (IUGR) infants at term. The placentas of women with IUGR appear to be fundamentally different from PE women with respect to endoglin, despite the proposed common pathology of deficient trophoblast invasion/spiral artery remodeling and poor placental perfusion.

Neonatal mortality risk related to birth weight and gestational age in British Columbia

OBJECTIVES

To provide gender-specific neonatal mortality grids depicting relative risk in narrow birth weight ranges at each week of gestation. The grids will provide practitioners with clinically relevant information pertinent to pregnancy, delivery, and postnatal care in Canada.

METHODS

Records from the British Columbia Vital Statistics Agency birth and death registries from 1981 to 2000 were deterministically linked and resulted in a 99.86% linkage rate. Risk ratios were computed by dividing percent neonatal mortality in 250 g birth weight categories at each week of gestation by the overall gender-specific mortality rates for the full period. We adjusted random rate fluctuations that were due to low frequencies in the narrow birth weight and gestational age strata.

RESULTS

Females exhibited greater survival across the full spectrum of birth weight by gestational age strata, but their mortality configurations were noticeably different from those of males. In addition, there were demarcations in both grids that depicted relatively abrupt changes in risk ratios. Although the crude mortality rates in BC decreased during the study period, the use of risk ratios reduced the disparity in crude rates over time.

CONCLUSION

These gender-specific mortality grids refine and enhance previously available comparisons by portraying neonatal mortality risks in narrow birth weight ranges at each week of gestation.

Disproportionate Intrauterine Growth Intervention Trial At Term: DIGITAT

Background

Around 80% of intrauterine growth restricted (IUGR) infants are born at term. They have an increase in perinatal mortality and morbidity including behavioral problems, minor developmental delay and spastic cerebral palsy. Management is controversial, in particular the decision whether to induce labour or await spontaneous delivery with strict fetal and maternal surveillance. We propose a randomised trial to compare effectiveness, costs and maternal quality of life for induction of labour versus expectant management in women with a suspected IUGR fetus at term.

Methods/design

The proposed trial is a multi-centre randomised study in pregnant women who are suspected on clinical grounds of having an IUGR child at a gestational age between 36+0 and 41+0 weeks. After informed consent women will be randomly allocated to either induction of labour or expectant management with maternal and fetal monitoring. Randomisation will be web-based. The primary outcome measure will be a composite neonatal morbidity and mortality. Secondary outcomes will be severe maternal morbidity, maternal quality of life and costs. Moreover, we aim to assess neurodevelopmental and neurobehavioral outcome at two years as assessed by a postal enquiry (Child Behavioral Check List-CBCL and Ages and Stages Questionnaire-ASQ). Analysis will be by intention to treat. Quality of life analysis and a preference study will also be performed in the same study population. Health technology assessment with an economic analysis is part of this so called Digitat trial (Disproportionate Intrauterine Growth Intervention Trial At Term). The study aims to include 325 patients per arm.

Discussion

This trial will provide evidence for which strategy is superior in terms of neonatal and maternal morbidity and mortality, costs and maternal quality of life aspects. This will be the first randomised trial for IUGR at term.

Trial registration

Dutch Trial Register and ISRCTN-Register: ISRCTN10363217.

Placental HIF-1 alpha, HIF-2 alpha, membrane and soluble VEGF receptor-1 proteins are not increased in normotensive pregnancies complicated by late-onset intrauterine growth restriction

Inadequate trophoblast invasion and spiral artery remodeling leading to poor placental perfusion are believed to underlie the pregnancy pathologies preeclampsia (PE) and intrauterine growth restriction (IUGR). The main objective of this study was to investigate hypoxia-inducible transcription factor-alpha (HIF-alpha) and downstream genes (VEGF receptor-1) Flt-1 and soluble fms-like tyrosine kinase 1 (sFlt-1) proteins in IUGR placentas. Placentas from normal pregnant (NP; n = 18), PE (n = 18), and IUGR (n = 10) patients were investigated. Normotensive patients with IUGR delivered babies at >or= 37 wk of gestation with birth weights of <10% and asymmetrical growth. HIF-1 alpha, -2 alpha, Flt-1, and sFlt-1 protein, and mRNA were assessed by Western and Northern blot analyses, respectively. The results are expressed as ratios of the densitometric values for each pair of pathologic and normal placentas, a ratio of 1.0 indicating no difference. Comparable to our earlier studies, the PE/NP ratios for HIF-1 alpha, -2 alpha, and Flt proteins were significantly increased by 50-100% (all P < 0.01 vs. 1.0). Unexpectedly, the IUGR/NP ratios for HIF-1 alpha and -2 alpha proteins were 1.03 +/- 0.07 and 0.96 +/- 0.16, respectively, and for Flt and sFlt were 1.14 +/- 0.15 and 0.95 +/- 0.12, respectively (all P = not significant vs. 1.0). Northern blot analysis revealed comparable levels of HIF-alpha mRNA in abnormal and normal placentas. In contrast to PE, HIF-alpha proteins and regulated genes are not increased in placentas from normotensive pregnant women delivering small, asymmetrically grown babies >or= 37 wk of gestation. The absence of an increase in HIF-alpha protein is not due to insufficient HIF-alpha mRNA for protein synthesis. Thus, the placentas from women with PE and late IUGR are fundamentally different at the molecular level.