New charts for ultrasound dating of pregnancy and assessment of fetal growth: longitudinal data from a population-based cohort study

Placental vascular dysfunction, fetal and childhood growth, and cardiovascular development: the generation R study

BACKGROUND

Suboptimal fetal nutrition may influence early growth and cardiovascular development. We examined whether umbilical and uterine artery resistance indices, as measures of feto-placental and utero-placental vascular function, respectively, are associated with fetal and childhood growth and cardiovascular development.

METHODS AND RESULTS

This study was embedded in a population-based prospective cohort study among 6716 mothers and their children. Umbilical artery pulsatility index and uterine artery resistance index and fetal growth were measured in third trimester. Childhood growth was repeatedly assessed from birth to the age of 6 years. We measured body fat distribution, left ventricular mass, and blood pressure at the age of 6 years. Higher third trimester umbilical and uterine artery vascular resistance were associated with lower fetal length and weight growth in third trimester resulting in a smaller size at birth among boys and girls (P values < 0.05). These differences in length and weight growth became smaller from the age of 6 months onwards, but were still present at the age of 6 years. Higher third trimester umbilical artery vascular resistance, but not uterine artery vascular resistance, was associated with higher childhood body mass index, total fat mass, android/gynoid fat mass ratio, and systolic blood pressure, and with a lower left ventricular mass (P values<0.05). These associations were not explained by birth weight. Stronger associations tended to be present among girls as compared with boys.

CONCLUSIONS

Higher third trimester feto-placental vascular resistance, but not utero-placental vascular resistance, was associated with slower fetal growth rates and cardiovascular adaptations in childhood.

Should a first trimester dating scan be routine for all pregnancies?

Accurate pregnancy dating is important for diagnostic and management decisions during pregnancy. Dating by last menstrual period is less reliable than dating by ultrasound, since the former has memory-related and other sources of inaccuracy. Dating by first trimester ultrasound, via the crown-rump length, has a 95% confidence range of ±5 days, slightly better than the ±8 days for dating by second trimester ultrasound at 14-20 weeks. This small difference appears to be too small to justify a routine first trimester scan for the purpose of dating the pregnancy.

Does 17-α-hydroxyprogesterone caproate affect fetal biometry and birth weight in twin pregnancy?

OBJECTIVE

Increasingly, maternal administration of 17-α-hydroxyprogesterone caproate (17-OHPC) is utilized to prevent preterm birth, but the fetal safety of 17-OHPC is still a matter of concern. This study aimed to assess whether exposure to 17-OHPC during the second and third trimesters of pregnancy affects fetal biometry in twin gestations.

METHODS

This study included a subset of women with a twin pregnancy who had been previously included in a randomized clinical trial comparing the effectiveness of 17-OHPC and placebo on neonatal outcomes and preterm birth rates in multiple pregnancy. In the present study, the individual growth patterns of femur length, head circumference and abdominal circumference were compared between fetuses of women who had been randomized to receive weekly injections of either 17-OHPC (n = 52) or placebo (n = 58) at between 16-20 and 36 weeks' gestation.

RESULTS

The three biometric variables assessed developed similarly in fetuses in both the group exposed to 17-OHPC and the placebo group during the second half of pregnancy. Birth weight adjusted for parity and fetal sex was also comparable between groups.

CONCLUSION

The use of 17-OHPC has no adverse effects on fetal biometry and birth weight in twins.

Somatic growth trajectory in the fetus with hypoplastic left heart syndrome

BACKGROUND

Fetal growth abnormalities in hypoplastic left heart syndrome (HLHS) have been documented primarily by birth measurements. Fetal growth trajectory has not been described. We hypothesized that fetal growth trajectory declines across late gestation in this population.

METHODS

Infants with a prenatal diagnosis of HLHS and no history of prematurity or a genetic syndrome were identified. Fetal ultrasound measurements and birth anthropometrics were obtained from clinical records. z-Scores for estimated fetal weight (EFWz) and birth weight (BWTz) were compared. BWTz for three neonatal standards were compared.

RESULTS

Paired fetal and neonatal data were identified in 33 cases of HLHS. Mean gestational age at ultrasound and birth were 27 and 38 wk, respectively. BWTz was lower than EFWz by a mean of 0.82 (SD: 0.72, P < 0.0001), with 64% of subjects demonstrating a decrease in z-score of >0.5. Umbilical artery (UA) Doppler found no evidence of significant placental insufficiency. Modest differences in BWTz were seen across BWT standards in this cohort.

CONCLUSION

The majority of fetuses with HLHS demonstrate decreased growth velocity during later pregnancy, suggesting growth abnormalities manifest in utero. The potential relationship to future clinical outcomes warrants further study.

Maternal soluble fms-like tyrosine kinase-1, placental growth factor, plasminogen activator inhibitor-2, and folate concentrations and early fetal size: the Generation R study

OBJECTIVE

Fetal growth is dependent on adequate development of the placenta. Impaired angiogenesis and vasculogenesis in early pregnancy compromises placental and embryonic development. The proteins soluble fms-like tyrosine kinase (sFlt)-1, placental growth factor (PlGF), and plasminogen activator inhibitor (PAI)-2, and the B vitamin folate are determinants of placental development. This study aims to identify associations between these maternal biomarkers and early fetal size.

STUDY DESIGN

From a prospective birth cohort study in The Netherlands, 1491 pregnant women were selected for this study. At a mean gestational age (GA) of 12.4 weeks (SD 0.8) maternal venous blood samples were obtained to determine the concentrations of sFlt-1, PlGF, PAI-2, and folate. Early fetal size was assessed with measurement of the crown-to-rump length (CRL) at a mean of 12.4 weeks' GA (SD 0.8). Analyses were performed using multivariable linear regression analyses with the biomarkers (continuous, quintiles) as regressors and CRL as main outcome measure.

RESULTS

Linear trend analysis showed positive associations between maternal sFlt-1 (P < .001), PlGF (P = .042), PAI-2 (P < .001), and folate (P = .039) and CRL. These associations were independent of GA, maternal age, height, body mass index, ethnicity, fetal sex, parity, educational level, smoking, and folic acid supplement use (folate not adjusted).

CONCLUSION

sFlt-1, PlGF, PAI-2, and folate are positively associated with first-trimester fetal size.

Uterine artery Doppler and sFlt-1/PlGF ratio: usefulness in diagnosis of pre-eclampsia

OBJECTIVE

To evaluate the usefulness of the mean pulsatility index of the uterine arteries (mPI-UtA) and automated measurement of the soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio on suspicion or at diagnosis of pre-eclampsia (PE).

METHODS

Patients with singleton pregnancies with PE (n = 60) diagnosed according to current recommendations, or with suspected PE (n = 32) defined by (1) blood pressure (BP) ≥ 160/100 mmHg, (2) BP ≥ 140/90 mmHg or proteinuria, together with suggestive clinical symptoms or (3) intrauterine growth restriction (IUGR) at < 34 + 0 weeks, were enrolled and mPI-UtA and the sFlt-1/PlGF ratio were measured. Values > 95(th) centile were considered abnormal. All cases were classified according to occurrence of PE and/or IUGR and subclassified, depending on gestational age at delivery, as early (< 34 + 0 weeks) or late (≥ 34 + 0 weeks).

RESULTS

PE was confirmed in 72 cases, in which 32 early deliveries occurred. Isolated IUGR was diagnosed in nine early cases and one late case, while the remaining 10 cases were late deliveries without PE or IUGR. In pregnancies in which PE and IUGR were excluded, mPI-UtA was abnormal in 40% but the sFlt-1/PlGF ratio was normal in 100%. In early PE, mPI-UtA at diagnosis was abnormal in 100% of cases with IUGR and in 91% without IUGR, while sFlt-1/PlGF was abnormal in 100% and 96%, respectively. In late PE, mPI-UtA was abnormal in 50% and 37% of cases with and without IUGR while the sFlt-1/PlGF ratio was abnormal in 50% and 26%, respectively.

CONCLUSION

Abnormal mPI-UtA and sFlt-1/PlGF ratio are common in early PE. In late PE, mPI-UtA is normal in most cases and thus not diagnostically useful. The sFlt-1/PlGF ratio shows high specificity but low sensitivity to confirm PE when suspected.

Risk factors and outcomes of maternal obesity and excessive weight gain during pregnancy

OBJECTIVE

The prevalence of overweight and obesity among women of reproductive age is increasing. We aimed to determine risk factors and maternal, fetal and childhood consequences of maternal obesity and excessive gestational weight gain.

DESIGN AND METHODS

The study was embedded in a population-based prospective cohort study among 6959 mothers and their children. The study was based in Rotterdam, The Netherlands (2001-2005).

RESULTS

Maternal lower educational level, lower household income, multiparity, and FTO risk allel were associated with an increased risk of maternal obesity, whereas maternal European ethnicity, nulliparity, higher total energy intake, and smoking during pregnancy were associated with an increased risk of excessive gestational weight gain (all p-values <0.05). As compared to normal weight, maternal obesity was associated with increased risks of gestational hypertension (OR 6.31 (95% CI 4.30, 9.26)), preeclampsia (OR (3.61, (95% CI 2.04, 6.39)), gestational diabetes (OR 6.28 (95%CI 3.01, 13.06)), caesarean delivery (OR 1.91 (95% CI 1.46, 2.50)), delivering large size for gestational age infants (OR 2.97 (95% CI 2.16, 4.08)), and childhood obesity (OR 5.02 (95% CI:2.97, 8.45)). Weaker associations of excessive gestational weight gain with maternal, fetal and childhood outcomes were observed, with the strongest effects for first trimester weight gain.

CONCLUSIONS

Our study shows that maternal obesity and excessive weight gain during pregnancy are associated with socio-demographic, lifestyle, and genetic factors and with increased risks of adverse maternal, fetal and childhood outcomes. As compared to prepregnancy overweight and obesity, excessive gestational weight gain has a limited influence on adverse pregnancy outcomes.

A de novo GLI3 mutation in a patient with acrocallosal syndrome

Acrocallosal syndrome is characterized by postaxial polydactyly, macrocephaly, agenesis of the corpus callosum, and severe developmental delay. In a few patients with this disorder, a mutation in the KIF7 gene has been reported, which was associated with impaired GLI3 processing and dysregulaton of GLI3 transcription factors. A single patient with acrocallosal syndrome and a de novo p.Ala934Pro mutation in GLI3 has been reported, whereas diverse and numerous GLI3 mutations have also been described in syndromes with overlapping clinical manifestations, including Greig cephalopolysyndactyly syndrome, Pallister-Hall syndrome, trigonocephaly with craniosynostosis and polydactyly, oral-facial-digital syndrome, and non-syndromic polydactyly. Here, we describe a second patient with acrocallosal syndrome, who has a de novo, novel c.2786T>C mutation in GLI3, which predicts p.Leu929Pro. This mutation is in the same domain as the mutation in the previously reported patient. These data confirm that mutations in GLI3 are a cause of the acrocallosal phenotype.

Levels of antibodies against tissue transglutaminase during pregnancy are associated with reduced fetal weight and birth weight

BACKGROUND & AIMS

Celiac disease in pregnant women has been associated with poor growth of the fetus, but little is known about how the level of celiac disease affects fetal growth or birth outcomes. We assessed the associations between levels of antibodies against tissue transglutaminase (anti-tTG, a marker of celiac disease) and fetal growth and birth outcomes for pregnant women.

METHODS

We performed a population-based prospective birth cohort study of 7046 pregnant women. Serum samples were collected during the second trimester of pregnancy and analyzed for levels of anti-tTG. Based on these levels, the women were categorized into 3 groups: negative anti-tTG (≤0.79 U/mL; n = 6702), intermediate anti-tTG (0.8 to ≤6 U/mL; n = 308), or positive anti-tTG (>6 U/mL; n = 36). Data on fetal growth and birth outcomes were collected from ultrasound measurements and medical records.

RESULTS

Fetuses of women in the positive anti-tTG group weighed 16 g less than those of women in the negative anti-tTG group (95% confidence interval [CI], -32 to -1 g) during the second trimester and weighed 74 g less (95% CI, -140 to -8 g) during the third trimester. Newborns of women in the intermediate and positive anti-tTG groups weighed 53 g (95% CI, -106 to -1 g) and 159 g (95% CI, -316 to -1 g) less at birth, respectively, than those of women in the negative anti-tTG group. The reduction in birth weight in offspring of mothers in the intermediate anti-tTG group was 2-fold greater among mothers who carried HLA-DQ2 or -DQ8 than among those without HLA-DQ2 or -DQ8.

CONCLUSIONS

Levels of anti-tTG in pregnant women are inversely associated with fetal growth. Growth was reduced to the greatest extent in fetuses of women with the highest levels of anti-tTG (>6 U/mL). Birth weight was also reduced in women with intermediate levels of anti-tTG (0.8 to ≤6 U/mL) and further reduced in those carrying HLA-DQ2 and -DQ8.

Fetal growth and prenatal exposure to bisphenol A: the generation R study

BACKGROUND

Prenatal exposure to bisphenol A (BPA) has been associated with adverse birth outcomes, but findings of previous studies have been inconsistent.

OBJECTIVE

We investigated the relation of prenatal BPA exposure with intrauterine growth and evaluated the effect of the number of measurements per subject on observed associations.

METHODS

This study was embedded in a Dutch population-based prospective cohort study, with urine samples collected during early, mid-, and late pregnancy. The study comprised 219 women, of whom 99 had one measurement, 40 had two measurements, and 80 had three measurements of urinary BPA. Fetal growth characteristics were repeatedly measured by ultrasound during pregnancy and combined with measurements at birth. Linear regression models for repeated measurements of both BPA and fetal growth were used to estimate associations between urinary concentrations of creatinine-based BPA (BPACB) and intrauterine growth.

RESULTS

The relationship between BPACB and fetal growth was sensitive to the number of BPA measurements per woman. Among 80 women with three BPA measurements, women with BPACB > 4.22 μg/g crea (creatinine) had lower growth rates for fetal weight and head circumference than did women with BPACB < 1.54 μg/g crea, with estimated differences in mean values at birth of -683 g (20.3% of mean) and -3.9 cm (11.5% of mean), respectively. When fewer measurements were available per woman, the exposure-response relationship became progressively attenuated and statistically nonsignificant.

CONCLUSION

Our findings suggest that maternal urinary BPA may impair fetal growth. Because previous studies have shown contradictory findings, further evidence is needed to corroborate these findings in the general population.

Human long bone development in vivo: analysis of the distal femoral epimetaphysis on MR images of fetuses

PURPOSE

To investigate human long bone development in vivo by analyzing distal femoral epimetaphyseal structures and bone morphometrics on magnetic resonance (MR) images of fetuses.

MATERIALS AND METHODS

An institutional review board approved this retrospective study, and informed consent was waived. Included were 272 MR imaging examinations (April 2004-July 2011) in 253 fetuses with a mean gestational age (GA) of 26 weeks 6 days (range, 19 weeks 2 days to 35 weeks 6 days) without known musculoskeletal abnormalities. Two independent readers qualitatively analyzed epiphyseal and metaphyseal shape, secondary ossification, and the perichondrium on 1.5-T echo-planar MR images and correlated the results with the GA that was derived from previous fetal ultrasonography (US). Diaphyseal and epiphyseal morphometric measurements were correlated with GA by means of the Pearson correlation and linear regression. MR imaging measurements of diaphyseal length and US normative values were compared graphically. Interreader agreement analysis was performed with weighted κ statistics and the intraclass correlation coefficient.

RESULTS

With advancing GA, the epiphyseal shape changed from spherical (r(2) = 0.664) to hemispherical with a notch (r(2) = 0.804), and the metaphyseal shape changed from flat (r(2) = 0.766) to clearly undulated (r(2) = 0.669). Secondary ossification (r(2) = 0.777) was not observed until 25 weeks 3 days. The perichondrium decreased (r(2) = 0.684) from 20 weeks onward. Correlation coefficients were 0.897 for diaphyseal length, 0.738 for epiphyseal length, and 0.801 for epiphyseal width with respect to GA. The range of measurements of diaphyseal length was larger than that of the reported US normative values. Interreader agreement was good for bone morphometrics (intraclass correlation coefficient, 0.906-0.976), and moderate for bone characteristics (weighted κ, 0.448-0.848).

CONCLUSION

Prenatal MR imaging allows visualization of human bone development in vivo by means of epimetaphyseal characteristics and bone morphometrics.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13112441/-/DC1.

Pediatric population-based neuroimaging and the Generation R Study: the intersection of developmental neuroscience and epidemiology

Neuroimaging studies of typically developing children and adolescents have provided valuable information on global and regional developmental trajectories of brain development. As these studies become larger and population-based, they are generating an intersection between the fields of developmental neuroscience and epidemiology. However, few of these studies have adequately probed the contribution of multiple environmental and genetic factors on brain development. Studies designed to optimally evaluate the role of multiple environmental and genetic factors on brain development require both large sample sizes and the prospective collection of multiple environmental factors. The Generation R Study is a large, prospective, prenatal-cohort study of nearly 10,000 children that began in 2002 in Rotterdam, the Netherlands. In September of 2009, 6-8 year old children from the Generation R Study were invited to participate in a magnetic resonance imaging component of the study. We provide an overview of the study design and experience for the first 801 children recruited for the neuroimaging component of the study. The protocol includes a 1-h neuropsychological assessment using the NEPSY-II, a mock scanning session, and a neuroimaging session that includes high-resolution structural, diffusion tensor, and resting-state functional MRI sequences. Image quality has been good to excellent in over 80% of the children to date. The infusion of imaging into the Generation R Study will set the stage for evaluating the role of multiple environmental and genetic factors in both typical and atypical neurodevelopment.

First trimester growth restriction and uterine artery blood flow in the second trimester as predictors of adverse pregnancy outcome

OBJECTIVES

To investigate if fetuses with first trimester growth restriction have poorer perfusion of the placenta compared to a control group, and to investigate whether first trimester growth restriction in combination with poor flow in the uterine arteries in the second trimester can be used to predict poor outcome.

STUDY DESIGN

Women with singleton pregnancies, where the gestational age estimated by crown-rump length (CRL) at the first trimester scan was 7 days or more smaller than the gestational age estimated by last menstrual period, and a control group of women, where the gestational age was either equal to or 1 day larger than the gestational age estimated by last menstrual period, were invited to join the study. The study entailed the routine scans; Down syndrome screening in gestational week 11-14 and an anomaly scan in gestational week 18-21. In addition to the routine scans the participants were offered a growth scan in gestational week 23-24. At the anomaly scan and growth scan, umbilical and uterine artery Doppler flows were measured.

RESULTS

182 cases and 230 controls were included in the study. The case and control groups showed no significant differences in placental blood flow characteristics at 18-21 weeks or 23-24 weeks. In our logistic regression models the only outcome that showed a significant association to the case group was birth weight below 2500 g. Having a CRL 7 days or more smaller than expected increased the risk of having a child with a birth weight below 2500 g with an odds ratio of 3.29.

CONCLUSIONS

We were unable to demonstrate a link between first trimester growth restriction and poor placental perfusion. The case group had increased risk of birth weight below 2500 g, but only with an odds ratio of 3. Therefore we do not recommend implementation of uterine or umbilical artery flow measurements specifically for fetuses with first trimester growth restriction.

Assessment of gestational age using cerebellar measurements at cranial ultrasound: what is the best approach?

BACKGROUND AND AIMS

Clinical assessment of gestational age (GA) in preterm infants can be challenging. Several ultrasound approaches for estimating GA using cerebellar measurements are reported, claiming to be simpler and more accurate than clinical assessment, but they are not widely used. We aimed to compare the accuracy of four previously described measurements and compare their use in preterm infants.

METHODS

We studied infants <32weeks of GA defined by in-vitro fertilization date or early fetal ultrasound, excluding infants with neurological problems. Vermis anterior-posterior diameter (VAPD), vermis height (VH), and transverse cerebellar diameter via anterior (TCDa) and mastoid fontanelles (TCDm) were measured.Estimated PMA was calculated using published equations, and compared to known PMA using intraclass correlation coefficient (ICC). Intra and inter-observer reliability were determined.

RESULTS

We studied 80 infants (mean GA 28.5weeks [range 24-32], mean post-natal age 5.7days). ICC was 0.761 (VAPD), 0.632 (VH), 0.115 (TCDa) and 0.825 (TCDm). The TCDm equation gave the best estimate of GA (mean estimate -2days; 95% CI±13.8days). TCDa and TCDm absolute measurements were similar for each infant. Accuracy for estimating GA was similar for appropriately grown and small-for-gestation infants. Inter and intra-observer reliability was very good for all measurements.

CONCLUSIONS

Three previously described equations for estimating GA from cerebellar measurements gave good estimates of GA in preterms. The equation described for TCDm gave the narrowest 95% CI. We recommend the TCDm equation for the estimation of GA in VLBW infants but the TCD measurement can be made via either the anterior or mastoid fontanelle.

Parental, fetal, and infant risk factors for preschool overweight: the Generation R Study

BACKGROUND

Overweight has its origins largely in early life. We aimed to identify the most important parental, fetal, and infant risk factors of preschool overweight.

METHODS

In a prospective cohort study, among 3,610 Caucasian preschool children, we assessed the associations of 34 putative parental, fetal, and infant factors with overweight risk.

RESULTS

Higher maternal BMI, paternal BMI, and birth weight were associated with higher risk of preschool overweight (odds ratio (OR): 1.23, 95% confidence interval (CI): 1.10, 1.39; OR: 1.35, 95% CI: 1.19, 1.53; and OR: 2.71, 95% CI: 2.27, 3.25, respectively, per SD increase). The same model identified low household income (OR: 1.74, 95% CI: 1.24, 2.45), being female (OR: 1.55, 95% CI: 1.20, 2.01), and experiencing third-trimester accelerated growth (OR: 1.73, 95% CI: 1.24, 2.40) or postnatal accelerated growth (OR: 6.39, 95% CI: 4.54, 8.99) as risk factors for preschool overweight. Higher polyunsaturated fat intake at 14 mo was associated with a lower risk of preschool overweight (OR: 0.77, 95% CI: 0.62, 0.96 per SD).

CONCLUSION

Parental anthropometrics and household income, fetal and infant accelerated growth, and infant dietary fat intake are the major risk factors for the development of preschool overweight. Further studies need to explore whether these risk factors could be potential targets for preventive interventions.

Changes in snuff and smoking habits in Swedish pregnant women and risk for small for gestational age births

OBJECTIVE

To examine associations between antenatal exposure to Swedish oral moist snuff (which includes essentially only nicotine) and to smoking and risks of small-for-gestational-age (SGA) births and to compare risks among women who stopped or continued using snuff or smoking during pregnancy.

DESIGN

Population-based cohort study.

SETTING

Sweden.

POPULATION

All live singleton births in Sweden 1999-2010.

METHODS

Odds ratios (OR) with 95% confidence intervals (CI) were calculated using multiple logistic regression analysis.

MAIN OUTCOME MEASURES

SGA birth, also stratified into preterm (≤36 weeks of gestation) and term (≥37 weeks of gestation) SGA births.

RESULTS

Compared with non-tobacco users in early pregnancy, snuff users and above all smokers in early pregnancy had increased risks of SGA births: adjusted ORs (95% CI) were 1.26 (1.09-1.46) and 2.55 (2.43-2.67), respectively). Snuff use had, if anything, a stronger association with preterm SGA than term SGA, whereas the opposite was true for smoking. Compared with non-tobacco users, women who stopped using snuff before their first visit to antenatal care had no increased risks of preterm or term SGA, and women who stopped using snuff later during pregnancy had no increased risk of term SGA. Smoking cessation early in pregnancy was associated with a larger reduction in risk than smoking cessation later in pregnancy.

CONCLUSIONS

As both smoking and snuff use influence risk of SGA, both nicotine but above all tobacco combustion products are involved in the mechanisms by which maternal smoking increases the risk of SGA.

The Generation R Study: design and cohort update 2012

The Generation R Study is a population-based prospective cohort study from fetal life until adulthood. The study is designed to identify early environmental and genetic causes and causal pathways leading to normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on six areas of research: (1) maternal health; (2) growth and physical development; (3) behavioural and cognitive development; (4) respiratory health and allergies; (5) diseases in childhood; and (6) health and healthcare for children and their parents. Main exposures of interest include environmental, endocrine, genetic and epigenetic, lifestyle related, nutritional and socio-demographic determinants. In total, n = 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. Response at baseline was 61 %, and general follow-up rates until the age of 6 years exceed 80 %. Data collection in mothers, fathers and children include questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome and epigenome wide association screen is available in the participating children. From the age of 5 years, regular detailed hands-on assessments are performed in a dedicated research center including advanced imaging facilities such as Magnetic Resonance Imaging. Eventually, results forthcoming from the Generation R Study contribute to the development of strategies for optimizing health and healthcare for pregnant women and children.

Development of a fetal weight chart using serial trans-abdominal ultrasound in an East African population: a longitudinal observational study

Objective

To produce a fetal weight chart representative of a Tanzanian population, and compare it to weight charts from Sub-Saharan Africa and the developed world.

Methods

A longitudinal observational study in Northeastern Tanzania. Pregnant women were followed throughout pregnancy with serial trans-abdominal ultrasound. All pregnancies with pathology were excluded and a chart representing the optimal growth potential was developed using fetal weights and birth weights. The weight chart was compared to a chart from Congo, a chart representing a white population, and a chart representing a white population but adapted to the study population. The prevalence of SGA was assessed using all four charts.

Results

A total of 2193 weight measurements from 583 fetuses/newborns were included in the fetal weight chart. Our chart had lower percentiles than all the other charts. Most importantly, in the end of pregnancy, the 10^th percentiles deviated substantially causing an overestimation of the true prevalence of SGA newborns if our chart had not been used.

Conclusions

We developed a weight chart representative for a Tanzanian population and provide evidence for the necessity of developing regional specific weight charts for correct identification of SGA. Our weight chart is an important tool that can be used for clinical risk assessments of newborns and for evaluating the effect of intrauterine exposures on fetal and newborn weight.

New first-trimester crown-rump length equations from a French general population

INTRODUCTION

The purpose of this study was to obtain precise knowledge of fetal biometric measurements, in particular crown-rump length (CRL). Our results have been carefully compared to equations found in the literature.

MATERIALS AND METHODS

Single-operator measurements of 2,123 spontaneous pregnancies from a general French population provided new statistical relationships between fetal age (FA) and CRL. Comparisons were made with measurements obtained from 402 in vitro fertilizations (IVFs) for which FA were known. Heteroskedastic and robust regressions were compared by cross-validation, and prediction errors were studied. All ultrasound measurements were taken during standard follow-ups of pregnancies, without any additional features.

RESULTS

From a cleaned subsample of 513 spontaneous pregnancies, we reported good modeling of first-term embryonic growth, with equations and predictions of standard deviations agreeing with objective datations for IVFs. Most precise CRL measurements were predicted for FA of 49 days.

DISCUSSION

Our results allow future detection of fetal growth abnormalities using Z-scores throughout the first trimester.

Systematic review of methodology used in ultrasound studies aimed at creating charts of fetal size

BACKGROUND

Reliable ultrasound charts are necessary for the prenatal assessment of fetal size, yet there is a wide variation of methodologies for the creation of such charts.

OBJECTIVE

To evaluate the methodological quality of studies of fetal biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods.

SEARCH STRATEGY

Electronic searches in MEDLINE, EMBASE and CINAHL, and references of retrieved articles.

SELECTION CRITERIA

Observational studies whose primary aim was to create ultrasound size charts for bi-parietal diameter, head circumference, abdominal circumference and femur length in fetuses from singleton pregnancies.

DATA COLLECTION AND ANALYSIS

Studies were scored against a predefined set of independently agreed methodological criteria and an overall quality score was given to each study. Multiple regression analysis between quality scores and study characteristics was performed.

MAIN RESULTS

Eighty-three studies met the inclusion criteria. The highest potential for bias was noted in the following fields: 'Inclusion/exclusion criteria', as none of the studies defined a rigorous set of antenatal or fetal conditions which should be excluded from analysis; 'Ultrasound quality control measures', as no study demonstrated a comprehensive quality assurance strategy; and 'Sample size calculation', which was apparent in six studies only. On multiple regression analysis, there was a positive correlation between quality scores and year of publication: quality has improved with time, yet considerable heterogeneity in study methodology is still observed today.

CONCLUSIONS

There is considerable methodological heterogeneity in studies of fetal biometry. Standardisation of methodologies is necessary in order to make correct interpretations and comparisons between different charts. A checklist of recommended methodologies is proposed.

Effect of various dating formulae on sonographic estimation of gestational age in extremely preterm infants

OBJECTIVES

Gestational age (GA) is one of the most important obstetric factors and prediction of date of delivery is usually based on ultrasonographic fetal measurements. Our aim was to determine whether applying three different dating formulae to a cohort of extremely preterm infants influenced the estimation of their GA.

METHODS

This was a study of 513 infants delivered before 27 gestational weeks, included in a Swedish national population study (EXPRESS), with information available on mid-trimester ultrasonographically measured biparietal diameter and femur length. We applied using these parameters three dating formulae, the Persson & Weldner formula, commonly used in Sweden, the Hadlock formula and the Mul formula, and compared their GA estimates to the clinically reported GA (recorded at delivery) and the last menstrual period (LMP)-based GA.

RESULTS

The mean reported GA was 173.2 days, corresponding well to the GA according to the Persson & Weldner dating formula (173.3). The mean GA according to LMP, the Hadlock formula and the Mul formula were 176.8, 175.3 and 175.6 days, respectively. The Hadlock and Mul GA estimates differed significantly from that based on the Persson & Weldner formula (both P-values < 10(-6)). Among 68 pregnancies with a reported duration of 22 weeks, 33 (49%) had a duration of 23 weeks or more when GA was calculated according to LMP and 22 (32%) when GA was calculated according to the Hadlock formula.

CONCLUSION

Estimated GA among infants delivered before 27 gestational weeks varied significantly depending on the dating formula used to calculate the estimated date of delivery; this might influence the clinical management of extremely preterm fetuses and infants.

Heritability estimates of body size in fetal life and early childhood

Background

The objective was to estimate the heritability for height and weight during fetal life and early childhood in two independent studies, one including parent and singleton offsprings and one of mono- and dizygotic twins.

Methods

This study was embedded in the Generation R Study (n = 3407, singletons) and the Netherlands Twin Register (n = 33694, twins). For the heritability estimates in Generation R, regression models as proposed by Galton were used. In the Twin Register we used genetic structural equation modelling. Parental height and weight were measured and fetal growth characteristics (femur length and estimated fetal weight) were measured by ultrasounds in 2^nd and 3^rd trimester (Generation R only). Height and weight were assessed at multiple time-points from birth to 36 months in both studies.

Results

Heritability estimates for length increased from 2^nd to 3^rd trimester from 13% to 28%. At birth, heritability estimates for length in singletons and twins were both 26% and 27%, respectively, and at 36 months, the estimates for height were 63% and 72%, respectively. Heritability estimates for fetal weight increased from 2^nd to 3^rd trimester from 17% to 27%. For birth weight, heritability estimates were 26% in singletons and 29% in twins. At 36 months, the estimate for twins was 71% and higher than for singletons (42%).

Conclusions

Heritability estimates for height and weight increase from second trimester to infancy. This increase in heritability is observed in singletons and twins. Longer follow-up studies are needed to examine how the heritability develops in later childhood and puberty.

Ultrasound Reference Chart Based on IVF Dates to Estimate Gestational Age at 6-9 weeks' Gestation

Accurate determination of gestational age underpins good obstetric care. We assessed the performance of six existing ultrasound reference charts to determine gestational age in 1268 singleton IVF pregnancies, where “true” gestational age could be precisely calculated from date of fertilisation. All charts generated dates significantly different to IVF dates (P < 0.0001 all comparisons). Thus we generated a new reference chart, The Monash Chart, based on a line of best fit describing crown-rump length across 6 + 1 to 9 + 0 weeks of gestation (true gestational age) in the IVF singleton cohort. The Monash Chart, but none of the existing charts, accurately determined gestational age among an independent IVF twin cohort (185 twin pairs). When applied to 3052 naturally-conceived singletons scans, The Monash Chart generated estimated due dates that were different to all existing charts (P ≤ 0.004 all comparisons). We conclude that commonly used ultrasound reference charts have inaccuracies. We have generated a CRL reference chart based on true gestational age in an IVF cohort that can accurately determine gestational age at 6–9 weeks of gestation.

Homocysteine and folate concentrations in early pregnancy and the risk of adverse pregnancy outcomes: the Generation R Study

OBJECTIVE

To investigate associations between early pregnancy homocysteine, folate and vitamin B12 concentrations and placental weight, birthweight and adverse pregnancy outcomes.

DESIGN

Population-based birth cohort study.

SETTING

Rotterdam, the Netherlands.

POPULATION

Cohort of 5805 pregnant women.

METHODS

To analyse homocysteine, folate and vitamin B12 concentrations, blood was drawn in early pregnancy. These concentrations were divided into quintiles. Information on birth outcomes was retrieved from medical records. Multivariate regression analyses were used.

MAIN OUTCOME MEASURES

Placental weight, birthweight, small for gestational age at birth (SGA) (<5th centile), prematurity and pre-eclampsia.

RESULTS

High homocysteine concentrations (highest quintile) were associated with lower placental weight (difference 30 g; P < 0.001) and birthweight (difference 110 g; P < 0.001), and increased risk of SGA [odds ratio (OR) 1.7; P = 0.006] compared with lowest quintile (reference). Low folate concentrations (lowest quintile) were associated with lower placental weight (difference 26 g; P = 0.001) and birthweight (difference 125 g; P < 0.001), and increased risks of SGA (OR 1.9; P = 0.002), prematurity (OR 2.2; P = 0.002) and pre-eclampsia (OR 2.1; P = 0.04) compared with highest quintile (reference). The risk of developing SGA and pre-eclampsia was substantially higher in women who had higher homocysteine and lower folate concentrations. No associations were found with vitamin B12.

CONCLUSIONS

Higher homocysteine and lower folate concentrations in early pregnancy are associated with lower placental weight and birthweight, and higher risk of adverse pregnancy outcomes. These findings suggest that high homocysteine and low folate concentrations in early pregnancy may adversely influence placentation and subsequently affect the success of pregnancy and birth outcomes.

Advantages of the population-based approach to pregnancy dating: results from 23,020 ultrasound examinations

OBJECTIVE

To confirm the results from two previous evaluations of term prediction models, including two sample-based models and one population-based model, in a third population.

METHODS

In a study population of 23,020 second-trimester ultrasound examinations, data were prospectively collected and registered over the period 1988-2009. Three different models for ultrasonically estimated date of delivery were applied to the measurements of fetal biparietal diameter (BPD) and two models were applied to the femur length (FL) measurements; the resulting term estimations were compared with the actual time of delivery. The difference between the actual and the predicted dates of delivery (the median bias) was calculated for each of the models, for three BPD/FL-measurement subgroups and for the study population as a whole.

RESULTS

For the population-based model, the median bias was + 0.4 days for the BPD-based predictions and - 0.4 days for the FL-based predictions, and the biases were stable over the inclusion ranges. The biases of the two traditional models varied with the size of the fetus at examination; median biases were - 0.87 and + 2.2 days, respectively, with extremes - 4.2 and + 4.8 days for the BPD-based predictions, and the median bias was + 1.72 days with range - 0.8 to + 4.5 days for FL-based predictions. The disagreement between the two sample-based models was never less than 2 days for the BPD-based predictions.

CONCLUSION

This study confirms the results from previous studies; median biases were negligible with term predictions from the population-based model, while those from the traditional models varied substantially. The biases, which have clinical implications, seem inevitable with the sample-based models, which, even if overall biases were removed, will perform unsatisfactorily.

Common variants at 12q15 and 12q24 are associated with infant head circumference

To identify genetic variants associated with head circumference in infancy, we performed a meta-analysis of seven genome-wide association studies (GWAS) (N = 10,768 individuals of European ancestry enrolled in pregnancy and/or birth cohorts) and followed up three lead signals in six replication studies (combined N = 19,089). rs7980687 on chromosome 12q24 (P = 8.1 × 10(-9)) and rs1042725 on chromosome 12q15 (P = 2.8 × 10(-10)) were robustly associated with head circumference in infancy. Although these loci have previously been associated with adult height, their effects on infant head circumference were largely independent of height (P = 3.8 × 10(-7) for rs7980687 and P = 1.3 × 10(-7) for rs1042725 after adjustment for infant height). A third signal, rs11655470 on chromosome 17q21, showed suggestive evidence of association with head circumference (P = 3.9 × 10(-6)). SNPs correlated to the 17q21 signal have shown genome-wide association with adult intracranial volume, Parkinson's disease and other neurodegenerative diseases, indicating that a common genetic variant in this region might link early brain growth with neurological disease in later life.

A common genetic variant at 15q25 modifies the associations of maternal smoking during pregnancy with fetal growth: the generation R study

OBJECTIVE

Maternal smoking during pregnancy is associated with fetal growth retardation. We examined whether a common genetic variant at chromosome 15q25 (rs1051730), which is known to be involved in nicotine metabolism, modifies the associations of maternal smoking with fetal growth characteristics.

METHODS

This study was performed in 3,563 European mothers participating in a population-based prospective cohort study from early pregnancy onwards. Smoking was assessed by postal questionnaires and fetal growth characteristics were measured by ultrasound examinations in each trimester of pregnancy.

RESULTS

Among mothers who did not smoke during pregnancy (82.9%), maternal rs1051730 was not consistently associated with any fetal growth characteristic. Among mothers who continued smoking during pregnancy (17.1%), maternal rs1051730 was not associated with head circumference. The T-allele of maternal rs1051730 was associated with a smaller second and third trimester fetal femur length [differences -0.23 mm (95%CI -0.45 to -0.00) and -0.41 mm (95%CI -0.69 to -0.13), respectively] and a smaller birth length [difference -2.61 mm (95%CI -5.32 to 0.11)]. The maternal T-allele of rs1051730 was associated with a lower third trimester estimated fetal weight [difference -33 grams (95%CI -55 to -10)], and tended to be associated with birth weight [difference -38 grams (95%CI -89 to 13)]. This association persisted after adjustment for smoking quantity.

CONCLUSIONS

Our results suggest that maternal rs1051730 genotype modifies the associations of maternal smoking during pregnancy with impaired fetal growth in length and weight. These results should be considered as hypothesis generating and indicate the need for large-scale genome wide association studies focusing on gene--fetal smoke exposure interactions.

The Mediterranean diet and fetal size parameters: the Generation R Study

Developmental adaptations due to early nutritional exposures may have permanent health consequences. Studies of diet and fetal size have mainly focused on individual nutrients despite evidence that the pattern of food consumption may be of significance. Hence, we evaluated the associations of dietary habits in early pregnancy (gestational age < 18 weeks) with fetal size, uteroplacental vascular resistance, placental weight and birth weight in a prospective observational study of 3207 Caucasian pregnant mothers in Rotterdam, the Netherlands. Participants completed a semiquantitative FFQ during early pregnancy. Logistic regression analysis was used to predict the occurrence of intra-uterine growth retardation at birth as a function of food intake. The derived solution was considered as the dietary pattern. As it was characterised by higher intakes of fruit, vegetables, vegetable oil, fish, pasta and rice, and lower intakes of meat, potatoes and fatty sauces, it was labelled the 'Mediterranean' diet. The degree of adherence to the diet was positively associated with plasma folate and serum vitamin B12 concentrations and showed an inverse relationship with homocysteine and high-sensitivity C-reactive protein plasma concentrations (P <0·05). Important fetal size and placental parameters were associated with the degree of adherence to the diet, revealing a 72 g lower birth weight (95% CI -110·8, -33·3) and a 15 g lower placental weight (95% CI -29·8, -0·2) for women with low adherence to the diet. To conclude, low adherence to a Mediterranean diet in early pregnancy seems associated with decreased intra-uterine size with a lower placental and a lower birth weight.

Ultrasound for nurses in reproductive medicine

Nurses are in an ideal position to perform pelvic ultrasound evaluations, and appropriately trained nurses can perform limited ultrasound evaluations as part of the assessment and treatment of infertility. In this article, the author provides detailed descriptions and accompanying ultrasonic images illustrating the use of ultrasound in providing vital clinical information in reproductive medicine and in the assessment of the first trimester of pregnancy.

Fetal and infant growth and asthma symptoms in preschool children: the Generation R Study

RATIONALE

Low birth weight is associated with an increased risk of wheezing in childhood.

OBJECTIVES

We examined the associations of longitudinally measured fetal and infant growth patterns with the risks of asthma symptoms in preschool children.

METHODS

This study was embedded in a population-based prospective cohort study among 5,125 children. Second- and third-trimester fetal growth characteristics (head circumference, femur length, abdominal circumference, and weight) were estimated by repeated ultrasounds. Infant growth (head circumference, length, and weight) was measured at birth and at the ages of 3, 6, and 12 months. Parental report of asthma symptoms until the age of 4 years was yearly obtained by questionnaires.

MEASUREMENTS AND MAIN RESULTS

Both fetal restricted and accelerated growth, defined as a negative or positive change of more than 0.67 standard deviation score, were not associated with asthma symptoms until the age of 4 years. Accelerated weight gain from birth to 3 months following normal fetal growth was associated with increased risks of asthma symptoms (overall odds ratio for wheezing: 1.44 [95% confidence interval: 1.22, 1.70]; shortness of breath: 1.32 [1.12, 1.56]; dry cough: 1.16 [1.01, 1.34]; persistent phlegm: 1.30 [1.07, 1.58]), but not with eczema (0.95 [0.80, 1.14]). These associations were independent of other fetal growth patterns and tended to be stronger for children of atopic mothers than for children of nonatopic mothers.

CONCLUSIONS

Weight-gain acceleration in early infancy was associated with increased risks of asthma symptoms in preschool children, independent of fetal growth. Early infancy might be a critical period for the development of asthma.

Occupational exposure to chemicals and fetal growth: the Generation R Study

BACKGROUND

Developmental diseases, such as birth defects, growth restriction and preterm delivery, account for >25% of infant mortality and morbidity. Several studies have shown that exposure to chemicals during pregnancy is associated with adverse birth outcomes. The aim of this study was to identify whether occupational exposure to various chemicals might adversely influence intrauterine growth patterns and placental weight.

METHODS

Associations between maternal occupational exposure to various chemicals and fetal growth were studied in 4680 pregnant women participating in a population-based prospective cohort study from early pregnancy onwards in the Netherlands (2002–2006), the Generation R Study. Mothers who filled out a questionnaire during mid-pregnancy (response: 77% of enrolment) were included if they conducted paid employment during pregnancy and had a spontaneously conceived singleton live born pregnancy (n = 4680). A job exposure matrix was used, linking job titles to expert judgement on exposure to chemicals in the workplace. Fetal growth characteristics were repeatedly measured by ultrasound and were used in combination with measurements at birth. Placental weight was obtained from medical records and hospital registries. Linear regression models for repeated measurements were used to study the associations between maternal occupational exposure to chemicals and intrauterine growth.

RESULTS

We observed that maternal occupational exposure to polycyclic aromatic hydrocarbons, phthalates, alkylphenolic compounds and pesticides adversely influenced several domains of fetal growth (fetal weight, fetal head circumference and fetal length). We found a significant association between pesticide and phthalate exposure with a decreased placental weight.

CONCLUSIONS

Our results suggest that maternal occupational exposure to several chemicals is associated with impaired fetal growth during pregnancy and a decreased placental weight. Further studies are needed to confirm these findings and to assess post-natal consequences.

Air pollution exposure during pregnancy, ultrasound measures of fetal growth, and adverse birth outcomes: a prospective cohort study

BACKGROUND

Air pollution exposure during pregnancy might have trimester-specific effects on fetal growth.

OBJECTIVE

We prospectively evaluated the associations of maternal air pollution exposure with fetal growth characteristics and adverse birth outcomes in 7,772 subjects in the Netherlands.

METHODS

Particulate matter with an aerodynamic diameter < 10 μm (PM10) and nitrogen dioxide (NO2) levels were estimated using dispersion modeling at the home address. Fetal head circumference, length, and weight were estimated in each trimester by ultrasound. Information on birth outcomes was obtained from medical records.

RESULTS

In cross-sectional analyses, NO2 levels were inversely associated with fetal femur length in the second and third trimester, and PM10 and NO2 levels both were associated with smaller fetal head circumference in the third trimester [-0.18 mm, 95% confidence interval (CI): -0.24, -0.12 mm; and -0.12 mm, 95% CI: -0.17, -0.06 mm per 1-μg/m3 increase in PM10 and NO2, respectively]. Average PM10 and NO2 levels during pregnancy were not associated with head circumference and length at birth or neonatally, but were inversely associated with birth weight (-3.6 g, 95% CI: -6.7, -0.4 g; and -3.4 g, 95% CI: -6.2, -0.6 g, respectively). Longitudinal analyses showed similar patterns for head circumference and weight, but no associations with length. The third and fourth quartiles of PM10 exposure were associated with preterm birth [odds ratio (OR) = 1.40, 95% CI: 1.03, 1.89; and OR = 1.32; 95% CI: 0.96, 1.79, relative to the first quartile]. The third quartile of PM10 exposure, but not the fourth, was associated with small size for gestational age at birth (SGA) (OR = 1.38; 95% CI: 1.00, 1.90). No consistent associations were observed for NO2 levels and adverse birth outcomes.

CONCLUSIONS

Results suggest that maternal air pollution exposure is inversely associated with fetal growth during the second and third trimester and with weight at birth. PM10 exposure was positively associated with preterm birth and SGA.

Folic acid supplements modify the adverse effects of maternal smoking on fetal growth and neonatal complications

Maternal smoking during pregnancy leads to increased risks of neonatal complications. The use of folic acid supplements might reduce the adverse effects of smoking. We examined whether folic acid supplement use modifies the associations of maternal smoking with first trimester plasma homocysteine concentrations, fetal growth characteristics, and risks of neonatal complications. The associations were studied in 6294 mothers participating in a prospective population-based cohort study in The Netherlands. Main outcomes measurements were first trimester plasma homocysteine concentrations, fetal growth characteristics, and neonatal complications, including preterm birth, low birth weight, and small-size-for-gestational-age. Continued maternal smoking was associated with higher first trimester plasma homocysteine concentrations [difference 0.52 μmol/L (95% range = 0.20, 2.14)], lower third trimester fetal weight (difference -44 g (95% CI = -57, -31)], and birth weight [difference -148 g (95% CI = -179, -118)]. There were significant interactions between maternal smoking and folic acid supplements on all outcome measures (all P-interaction < 0.040). Among mothers who continued smoking during pregnancy, those who did not use folic acid supplements had the highest risk of delivering a child with low birth weight [OR = 3.45 (95% CI = 1.25, 9.54)] compared to those who did use periconceptional folic acid supplements. No significant effects were observed for the risks of preterm birth and small-size-for-gestational-age at birth. Our results suggest that some adverse effects of maternal smoking on fetal growth and neonatal outcomes might be reduced by the use of folic acid supplements. The observed interaction seems to be mainly driven by smoking in the first trimester only.

Individually customised fetal weight charts derived from ultrasound measurements: the Generation R Study

Maternal and fetal characteristics are important determinants of fetal growth potential, and should ideally be taken into consideration when evaluating fetal growth variation. We developed a model for individually customised growth charts for estimated fetal weight, which takes into account physiological maternal and fetal characteristics known at the start of pregnancy. We used fetal ultrasound data of 8,162 pregnant women participating in the Generation R Study, a prospective, population-based cohort study from early pregnancy onwards. A repeated measurements regression model was constructed, using backward selection procedures for identifying relevant maternal and fetal characteristics. The final model for estimating expected fetal weight included gestational age, fetal sex, parity, ethnicity, maternal age, height and weight. Using this model, we developed individually customised growth charts, and their corresponding standard deviations, for fetal weight from 18 weeks onwards. Of the total of 495 fetuses who were classified as small size for gestational age (<10th percentile) when fetal weight was evaluated using the normal population growth chart, 80 (16%) were in the normal range when individually customised growth charts were used. 550 fetuses were classified as small size for gestational age using individually customised growth charts, and 135 of them (25%) were classified as normal if the unadjusted reference chart was used. In conclusion, this is the first study using ultrasound measurements in a large population-based study to fit a model to construct individually customised growth charts, taking into account physiological maternal and fetal characteristics. These charts might be useful for use in epidemiological studies and in clinical practice.

Comparison of measurements of the transverse diameter and perimeter of the fetal thymus obtained by magnetic resonance and ultrasound imaging

PURPOSE

To compare measurements of the fetal thymus obtained by magnetic resonance imaging (MRI) and ultrasound (US).

MATERIALS AND METHODS

Written informed consent was obtained from the patients that participated in this Institutional Review Board-approved observational study. The study population consisted of 17 pregnant women carrying fetuses between 21 and 34 weeks of gestation with suspected abnormalities. The transverse diameter and perimeter of the thymus were measured in these fetuses at the level of an axial view of the thorax that includes the pulmonary, aorta, and superior vena cava. The degree of agreement between MRI and US measurements was determined using Lin's concordance correlation coefficient and Bland-Altman analysis.

RESULTS

The mean (standard deviation, SD) gestational age at the time of the prenatal evaluation was 28.4 weeks (3.6). The thymus was measured by MRI and US in all cases. Comparison of the measurements from these two imaging modalities demonstrated a relatively good reproducibility with no evidence of systematic error.

CONCLUSION

MRI and US measurements of the fetal thymus during the second half of pregnancy are comparable. This finding suggests that MRI can become a useful adjuvant to US for assessment of the fetal thymus.

Blood pressure in different gestational trimesters, fetal growth, and the risk of adverse birth outcomes: the generation R study

Researchers have suggested that maternal hypertensive disorders during pregnancy affect fetal growth. The authors examined the associations between systolic and diastolic blood pressures in different trimesters of pregnancy and both repeatedly measured fetal growth characteristics and the risks of adverse birth outcomes. The present study (2001-2005) was performed in 8,623 women who were participating in a population-based prospective cohort study from fetal life onwards. Blood pressure and fetal growth characteristics were assessed in each trimester of pregnancy. Information on hypertensive complications and adverse birth outcomes was obtained from medical records. The results suggested that higher blood pressure was associated with smaller fetal head circumference and femur length, as well as lower fetal weight from the third trimester onward. An increase in blood pressure from the second trimester to the third trimester was associated with an increased risk of adverse birth outcomes. Compared with women who did not experience hypertension during pregnancy, women with preeclampsia had increased risks of having children who were preterm (odds ratio = 5.89, 95% confidence interval: 2.63, 13.14), had a low birth weight (odds ratio = 8.94, 95% confidence interval: 6.19, 12.90), or were small for their gestational age (odds ratio = 5.03, 95% confidence interval: 3.31, 7.62). The present results suggest that higher maternal blood pressure is associated with impaired fetal growth during the third trimester of pregnancy and increased risks of adverse birth outcomes.

Fetal and infant growth and the risk of obesity during early childhood: the Generation R Study

OBJECTIVE

To examine whether infant growth rates are influenced by fetal growth characteristics and are associated with the risks of overweight and obesity in early childhood.

DESIGN

This study was embedded in the Generation R Study, a population-based prospective cohort study from fetal life onward.

METHODS

Fetal growth characteristics (femur length (FL) and estimated fetal weight (EFW)) were assessed in the second and third trimesters and at birth (length and weight). Infant peak weight velocity (PWV), peak height velocity (PHV), and body mass index at adiposity peak (BMIAP) were derived for 6267 infants with multiple height and weight measurements.

RESULTS

EFW measured during the second trimester was positively associated with PWV and BMIAP during infancy. Subjects with a smaller weight gain between the third trimester and birth had a higher PWV. FL measured during the second trimester was positively associated with PHV. Gradual length gain between the second and third trimesters and between the third trimester and birth were associated with higher PHV. Compared with infants in the lowest quintile, the infants in the highest quintile of PWV had strongly increased risks of overweight/obesity at the age of 4 years (odds ratio (95% confidence interval): 15.01 (9.63, 23.38)).

CONCLUSION

Fetal growth characteristics strongly influence infant growth rates. A higher PWV, which generally occurs in the first month after birth, was associated with an increased risk of overweight and obesity at 4 years of age. Longer follow-up studies are necessary to determine how fetal and infant growth patterns affect the risk of disease in later life.

Evaluation of modified retinopathy of prematurity screening guidelines using birth weight as the sole inclusion criterion

PURPOSE

The purpose was to determine if birth weight (BW) alone can be the sole criterion for screening infants at risk for retinopathy of prematurity (ROP).

MATERIALS AND METHODS

In this retrospective, observational case series, 208 infants were screened for ROP using the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) Guidelines (1997). Variables examined included gestational age (GA), birth weight (BW), and a composite variable BWGA Index [(grams × weeks)/1000], which takes into consideration both the birth weight and gestational age of the infant. Infants were divided into two groups: Group 1, BW ≤1250 g, and Group 2, BW >1250 g. Multivariate analysis was performed to detect factors predictive of ROP. Receiver operator characteristic (ROC) curves were generated to determine the efficacy of screening using the BW, GA, and BWGA Index. Statistical analyses were performed with logistic regression with a P-value of 0.05 or less indicating statistical significance.

RESULTS

Varying stages of ROP were present in 116 of 416 eyes. Of the 105 eyes in Group 2, only 1 eye developed stage 1 ROP. Only Group 1 eyes developed stage 3 or higher ROP. The ROC curve for BW alone gave an area under the curve (AUC) of 0.797 (standard error [SE] = 0.0329, P < 0.0001); for GA, AUC was 0.801 (SE = 0.0340, P < 0.0001) and for the BWGA Index, the AUC was 0.808 (SE = 0.0324, P < 0.0001). Using 1250-g BW as a criterion for ROP screening would have decreased the number of screenings by 24%, and did not exclude any ROP higher than stage 1.

CONCLUSION

Data from our neonatal intensive care unit suggest that birth weight ≤ 1250 g alone is an adequate parameter to identify premature infants at risk for ROP.

Estimation of gestational age from fundal height: a solution for resource-poor settings

Many women in resource-poor settings lack access to reliable gestational age assessment because they do not know their last menstrual period; there is no ultrasound (US) and methods of newborn gestational age dating are not practised by birth attendants. A bespoke multiple-measures model was developed to predict the expected date of delivery determined by US. The results are compared with both a linear and a nonlinear model. Prospectively collected early US and serial symphysis-pubis fundal height (SFH) data were used in the models. The data were collected from Karen and Burmese women attending antenatal care on the Thai–Burmese border. The multiple-measures model performed best, resulting in a range of accuracy depending on the number of SFH measures recorded per mother (for example six SFH measurements resulted in a prediction accuracy of ±2 weeks). SFH remains the proxy for gestational age in much of the resource-poor world. While more accurate measures should be encouraged, we demonstrate that a formula that incorporates at least three SFH measures from an individual mother and the slopes between them provide a significant increase in the accuracy of prediction compared with the linear and nonlinear formulae also using multiple SFH measures.