UNASSIGNED: Fetal growth restriction is associated with perinatal morbidity and mortality. Early identification of women having at-risk fetuses can reduce perinatal adverse outcomes.
UNASSIGNED: To assess the predictive performance of existing models predicting fetal growth restriction and birthweight, and if needed, to develop and validate new multivariable models using individual participant data.
UNASSIGNED: Individual participant data meta-analyses of cohorts in International Prediction of Pregnancy Complications network, decision curve analysis and health economics analysis.
UNASSIGNED: Pregnant women at booking. External validation of existing models (9 cohorts, 441,415 pregnancies); International Prediction of Pregnancy Complications model development and validation (4 cohorts, 237,228 pregnancies).
UNASSIGNED: Maternal clinical characteristics, biochemical and ultrasound markers.
UNASSIGNED: fetal growth restriction defined as birthweight <10th centile adjusted for gestational age and with stillbirth, neonatal death or delivery before 32 weeks\' gestation birthweight.
UNASSIGNED: First, we externally validated existing models using individual participant data meta-analysis. If needed, we developed and validated new International Prediction of Pregnancy Complications models using random-intercept regression models with backward elimination for variable selection and undertook internal-external cross-validation. We estimated the study-specific performance (c-statistic, calibration slope, calibration-in-the-large) for each model and pooled using random-effects meta-analysis. Heterogeneity was quantified using τ2 and 95% prediction intervals. We assessed the clinical utility of the fetal growth restriction model using decision curve analysis, and health economics analysis based on National Institute for Health and Care Excellence 2008 model.
UNASSIGNED: Of the 119 published models, one birthweight model (Poon) could be validated. None reported fetal growth restriction using our definition. Across all cohorts, the Poon model had good summary calibration slope of 0.93 (95% confidence interval 0.90 to 0.96) with slight overfitting, and underpredicted birthweight by 90.4 g on average (95% confidence interval 37.9 g to 142.9 g). The newly developed International Prediction of Pregnancy Complications-fetal growth restriction model included maternal age, height, parity, smoking status, ethnicity, and any history of hypertension, pre-eclampsia, previous stillbirth or small for gestational age baby and gestational age at delivery. This allowed predictions conditional on a range of assumed gestational ages at delivery. The pooled apparent c-statistic and calibration were 0.96 (95% confidence interval 0.51 to 1.0), and 0.95 (95% confidence interval 0.67 to 1.23), respectively. The model showed positive net benefit for predicted probability thresholds between 1% and 90%. In addition to the predictors in the International Prediction of Pregnancy Complications-fetal growth restriction model, the International Prediction of Pregnancy Complications-birthweight model included maternal weight, history of diabetes and mode of conception. Average calibration slope across cohorts in the internal-external cross-validation was 1.00 (95% confidence interval 0.78 to 1.23) with no evidence of overfitting. Birthweight was underestimated by 9.7 g on average (95% confidence interval -154.3 g to 173.8 g).
UNASSIGNED: We could not externally validate most of the published models due to variations in the definitions of outcomes. Internal-external cross-validation of our International Prediction of Pregnancy Complications-fetal growth restriction model was limited by the paucity of events in the included cohorts. The economic evaluation using the published National Institute for Health and Care Excellence 2008 model may not reflect current practice, and full economic evaluation was not possible due to paucity of data.
UNASSIGNED: International Prediction of Pregnancy Complications models\' performance needs to be assessed in routine practice, and their impact on decision-making and clinical outcomes needs evaluation.
UNASSIGNED: The International Prediction of Pregnancy Complications-fetal growth restriction and International Prediction of Pregnancy Complications-birthweight models accurately predict fetal growth restriction and birthweight for various assumed gestational ages at delivery. These can be used to stratify the risk status at booking, plan monitoring and management.
UNASSIGNED: This study is registered as PROSPERO CRD42019135045.
UNASSIGNED: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 17/148/07) and is published in full in Health Technology Assessment; Vol. 28, No. 14. See the NIHR Funding and Awards website for further award information.
One in ten babies is born small for their age. A third of such small babies are considered to be ‘growth-restricted’ as they have complications such as dying in the womb (stillbirth) or after birth (newborn death), cerebral palsy, or needing long stays in hospital. When growth restriction is suspected in fetuses, they are closely monitored and often delivered early to avoid complications. Hence, it is important that we identify growth-restricted babies early to plan care. Our goal was to provide personalised and accurate estimates of the mother’s chances of having a growth-restricted baby and predict the baby’s weight if delivered at various time points in pregnancy. To do so, first we tested how accurate existing risk calculators (‘prediction models’) were in predicting growth restriction and birthweight. We then developed new risk-calculators and studied their clinical and economic benefits. We did so by accessing the data from individual pregnant women and their babies in our large database library (International Prediction of Pregnancy Complications). Published risk-calculators had various definitions of growth restriction and none predicted the chances of having a growth-restricted baby using our definition. One predicted baby’s birthweight. This risk-calculator performed well, but underpredicted the birthweight by up to 143 g. We developed two new risk-calculators to predict growth-restricted babies (International Prediction of Pregnancy Complications-fetal growth restriction) and birthweight (International Prediction of Pregnancy Complications-birthweight). Both calculators accurately predicted the chances of the baby being born with growth restriction, and its birthweight. The birthweight was underpredicted by <9.7 g. The calculators performed well in both mothers predicted to be low and high risk. Further research is needed to determine the impact of using these calculators in practice, and challenges to implementing them in practice. Both International Prediction of Pregnancy Complications-fetal growth restriction and International Prediction of Pregnancy Complications-birthweight risk calculators will inform healthcare professionals and empower parents make informed decisions on monitoring and timing of delivery.

BACKGROUND: Previous studies have shown that job strain is associated with low birthweight (LBW), preterm birth (PTB), and small for gestational age (SGA). We conducted a scoping review and meta-analysis to assess the association between job strain and adverse pregnancy outcomes.
METHODS: A literature search was performed on PubMed. We included English-language studies that examined the association between job strain (based on the Karasek demand-control model) and pregnancy outcomes. We excluded letters, posters, reviews, and qualitative studies. Random effects meta-analysis was performed. Heterogeneity was assessed using τ2 and I2 statistics. Potential bias was assessed using standard funnel plots. Asymmetry was evaluated by Egger\'s test. Leave-one-out analysis was performed for sensitivity analyses.
RESULTS: Three eligible studies were found for LBW, seven for PTB, and four for SGA. The number of subjects ranged from 135 to 4889, and the prevalence of high job strain ranged from 6.64% to 33.9%. The pooled odds ratio and 95% confidence interval (CI) for LBW, PTB, and SGA were 1.23 (95% CI: 0.97, 1.56), 1.10 (95% CI: 1.00, 1.22), and 1.16 (95% CI: 0.97, 1.39) respectively, indicating modest associations. Heterogeneity for LBW and PTB may not be important but may be moderate for SGA. No publication bias was detected for LBW and PTB, but possible publication bias exists for SGA.
CONCLUSIONS: We found a modest association between job strain and PTB. Since job strain is only one of the many aspects of an unhealthy work environment, interventions that improve working conditions more broadly are needed.

OBJECTIVE: Low birthweight is an issue during pregnancy associated with an increased risk of developing liver disease later in life. Previous Mendelian randomisation (MR) studies which explored this issue have not isolated the direct impact of the foetus on birthweight. In the present study, MR was used to assess whether direct foetal effects on birthweight were causally associated with liver structure, function and disease risk independent of intrauterine effects.
METHODS: We extracted single nucleotide polymorphisms (SNPs) from genome-wide association studies (GWAS) about direct foetal-affected birthweight (321 223 cases) to conduct univariable and multivariable MR analyses to explore the relationships between birthweight and 4 liver structure measures, 9 liver function measures and 18 liver diseases. A two-step MR analysis was used to further assess and quantify the mediating effects of the mediators.
RESULTS: When isolating direct foetal effects, genetically predicted lower birthweight was associated with a higher risk of non-alcoholic fatty liver disease (NAFLD) (odds ratios [OR], 95% confidence interval [CI]: 1.61, 1.29-2.02, p < 0.001), higher magnetic resonance imaging [MRI] proton density fat fraction (PDFF) and higher serum gamma glutamyltransferase (GGT). Two-step MR identified two candidate mediators that partially mediate the direct foetal effect of lower birthweight on NAFLD, including fasting insulin (proportion mediated: 22.29%) and triglycerides (6.50%).
CONCLUSIONS: Our MR analysis reveals a direct causal association between lower birthweight and liver MRI PDFF, as well as the development of NAFLD, which persisted even after accounting for the potential influence of maternal factors. In addition, we identified fasting insulin and triglycerides as mediators linking birthweight and hepatic outcomes, providing insights for early clinical interventions.

OBJECTIVE: The causal relationship between life course adiposity with metabolic dysfunction-associated steatotic liver disease (MASLD) is ambiguous. We aimed to investigate whether there is an independent genetic causal relationship between body size at various life course and MASLD.
METHODS: We performed univariable and multivariable Mendelian randomization (MR) to estimate the causal effect of body size at different life stages on MASLD (i.e., defined by the clinical comprehensive diagnosis from the electronic health record [HER] codes [ICD9/ICD10] or diagnostic phrases), including birthweight, childhood body mass index (BMI), adult BMI, waist circumference (WC), waist-to-hip ratio (WHR), body fat percentage (BFP).
RESULTS: In univariate analyses, higher genetically predicted lower birthweight (ORIVW = 0.61, 95%CI, 0.52 to 0.74), Childhood BMI ( ORIVW = 1.37, 95%CI, 1.12 to 1.64), and adult BMI (ORIVW = 1.41, 95%CI, 1.27 to 1.57) was significantly associated with subsequent risk of MASLD after Bonferroni correction. The MVMR analysis demonstrated compelling proof that birthweight and adult BMI had a direct causal relationship with MASLD. However, after adjusting for birthweight and adult BMI, the direct causal relationship between childhood BMI and MASLD disappeared.
CONCLUSIONS: For the first time, this MR elucidated new evidence for the effect of life course adiposity on MASLD risk, providing lower birthweight and duration of obesity are independent risk factors for MASLD. Our findings indicated that weight management during distinct time periods plays a significant role in the prevention and treatment of MASLD.

Exposure to mercury (Hg) and lead (Pb), in combination with liver and kidney impairment, may result in adverse birth outcomes. From 408 women in the age range of 16 to 46 years, living in rural and urban areas in the interior of Suriname, we looked at the association between adverse birth outcomes and exposure to Hg and Pb in combination with liver and kidney function. This group of women represented a subcohort of pregnant women who participated in the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH)-Meki Tamara study. Liver function was assessed by measuring aspartate amino transferase (AST), alanine amino transferase (ALT), and gamma-glutamyl transferase (GGT). Kidney function was assessed by measuring creatinine, urea, and cystatin C. We defined preterm births as birth before 37 weeks of gestation, low birthweight as birthweight < 2500 g, and low Apgar score as a score < 7 at 5 min, and these were used as indicators for adverse birth outcomes. Small size for gestational age was defined as gestational age < -2SD weight for GA. We found significant statistical associations between biomarkers for liver and kidney functions and adverse birth outcomes Apgar score and gestational age. No significant association was found between heavy metals Hg and lead and adverse birth outcomes.

We studied mean changes in birthweight from the first to the second delivery according to length of the inter-pregnancy interval. We also studied recurrence risk of low birthweight, preterm birth and perinatal death. We followed all women in Norway from their first to their second singleton delivery at gestational week 22 or beyond during the years 1970-2019, a total of 654 100 women. Data were obtained from the Medical Birth Registry of Norway. Mean birthweight increased from the first to the second delivery, and the increase was highest in pregnancies conceived < 6 months after the first delivery; adjusted mean birthweight increase 227 g (g) (95% CI; 219-236 g), 90 g higher than in pregnancies conceived 6-11 months after the first delivery (137 g (95% CI; 130-144 g)). After exclusion of women with a first stillbirth, the mean increase in birthweight at inter-pregnancy interval < 6 months was attenuated (152 g, 95% CI; 143-160 g), but remained higher than at longer inter-pregnancy intervals. This finding was particularly prominent in women > 35 years (218 g, 95% CI; 139 -298 g). In women with a first live born infant weighing < 2500 g, mean birthweight increased by around 1000 g to the second delivery, and the increase was most prominent at < 6 months inter-pregnancy interval. We found increased recurrence risk of preterm birth at inter-pregnancy interval < 6 months, but no increased recurrence risk of low birthweight, small for gestational age infant or perinatal death. In conclusion, we found the highest mean increase in birthweight when the inter-pregnancy interval was short. Our results do not generally discourage short pregnancy intervals.

BACKGROUND: Small for gestational age (SGA) neonates are known to be at an elevated risk for neonatal morbidity. Despite this, there is a growing array of proposed size standards for identifying SGA fetuses. Given the inherent differences in design, acquisition methods, and the characteristics of the populations they represent, the generalizability of these standards to diverse populations remains uncertain.
BACKGROUND: This study aimed to assess variations in rates of SGA and severe SGA using six distinct size standards: Hadlock, Fetal Medicine Foundation (FMF), World Health Organization (WHO), Intergrowth-21 (IG-21), and two locally derived population-based size standards. The objective was to examine the differences in SGA and severe SGA rates among these size standards.
METHODS: A retrospective cohort study was conducted, encompassing all singleton deliveries in two tertiary referral hospital campuses with an annual birth count exceeding 10,000, from January 2019 to July 2022. SGA and severe SGA were defined as birthweights below the 10th or 3rd percentile, respectively, based on each growth standard. The study design included details on the setting, subjects (singleton deliveries), and the chosen size standards. Comparative analyses were performed to assess variations in SGA and severe SGA rates among these size standards.
RESULTS: Our study analyzed 32,912 singleton deliveries. We found that the choice of growth standard significantly impacted the rates of both SGA and severe SGA infants. Notably, the WHO criteria identified 5,548 (16.9 %) fetuses as SGA, compared to only 1,716 (5.2 %) using the INTERGROWTH-21 standard (p < 0.001). Similarly, for severe SGA, the FMF charts classified 2098 (6.37 %) infants, significantly higher than the 320 (1 %) identified by Dolberg\'s local population-based charts (p < 0.001).
CONCLUSIONS: Our study demonstrates a significant variety of SGA and severe SGA rates using different size standards. Therefore, the decision on the size standards in use is critical given the significant influence on clinical management.
CONCLUSIONS: There are significant variations in SGA and Severe SGA rates depending on the chosen size standard.

OBJECTIVE: Customized birthweight centiles have improved the detection of small for gestational age (SGA) and large for gestational age (LGA) babies compared to existing population standards. This study used perinatal registry data to derive coefficients for developing customized growth charts for Qatar.
METHODS: The PEARL registry data on women delivering in Qatar (2017-2018) was used to develop a multivariable linear regression model predicting optimal birthweight. Physiological variables included gestational age, maternal height, weight, ethnicity, parity, and sex of the baby. Pathological variables such as hypertension, preexisting and gestational diabetes and smoking were calculated and excluded to derive the optimal weight at term.
RESULTS: The regression model found a term optimal birthweight of 3,235 g for a Qatari nationality mother with median height (159 cm), booking weight (72 kg), parity (1) and gestation at birth (276 days) at the end of an uncomplicated pregnancy. Constitutional coefficients significantly affecting birthweight were gestational age, height, weight, and parity. The main pathological factors were preexisting diabetes (increase by +175.7 g) and smoking (decrease by -190.9 g). The SGA and LGA rates in the entire cohort after applying the population-specific customized centiles were 11.1 and 12.2 %, respectively (contrasting with the Hadlock standard: SGA-26.3 % and LGA-1.8 %, and Fenton standard: SGA-12.9 % and LGA-4.0 %).
CONCLUSIONS: Constitutional and pathological variations in fetal growth and birthweight apply in the maternity population in Qatar and have been quantified to allow the generation of customised charts for better identification of pregnancies with abnormal growth. Currently in-use population standards may misdiagnose many SGA and LGA babies.

The etiology of spina bifida, a neural tube birth defect, is largely unknown, but a majority of cases are thought to be genetic in origin. Although maternal blood type was found not to be associated with the occurrence of spina bifida, the analysis was never extended to other aspects of the disorder. The purpose of this descriptive study was to determine if maternal blood type was related to characteristics of children with spina bifida. The blood type of 221 mothers of children with spina bifida enrolled on the Arkansas Spinal Cord Disability Registry from 1995 to 2008 was obtained by mailed questionnaire. All children were community-dwelling and from singleton pregnancies. As expected, analysis of mother-child data showed that the distribution of mothers\' blood type was not statistically different from the general population (chi-squared, P = 0.9203). However, the blood type of these mothers was associated with their child\'s lesion level (chi-squared, P = 0.011). Mothers with blood type A more frequently had children with thoracic lesions; mothers with non-A blood types more frequently had children with lumbar and sacral lesions. In addition, mean birthweight differed by mothers\' blood type (analysis of variance, P = 0.025). Children of mothers with blood type A had the highest mean birthweight, while those of mothers with blood type AB had the lowest. Also, hydrocephalus was present more frequently in children with thoracic lesions compared to those with lumbar and sacral lesions (chi-squared, P = 0.001). Interestingly, these results were significant for female children but not for male children. In conclusion, maternal blood type was associated with lesion level and birthweight of children with spina bifida.

5-hydroxymethylcytosine (5hmC), formed through the ten-eleven translocation (TET) methylcytosine dioxygenase mediated oxidation of 5-methylcytosine (5mC) at cytosine-phosphate-guanine (CpG) dinucleotides, is believed to mainly serve as an intermediate in the DNA demethylation pathway, though recent evidence suggests that 5hmC may also play a functionally relevant role. We have conducted an epigenome-wide association study (EWAS) to assess the association between placenta 5hmC, obtained through parallel bisulfite and oxidative bisulfite modification of DNA and array-based assessment, and newborn birthweight in the Rhode Island Child Health Study (RICHS). We also assessed whether the removal of 5hmC signal impacts the observed results from traditional epigenome-wide studies that rely on BS modification-based (combined 5mC and 5hmC) assessment alone. We identified 5hmC at one CpG in the CUBN gene to be significantly associated with birthweight (FDR < 0.05) and demonstrate that expression of that gene was also associated with birthweight. Comparison of 5hmC+5mC and 5mC EWAS effect estimates reveal a strong correlation (r = 0.77, p < 0.0001). Our study suggests that traditional assessment of 5mC through bisulfite modification alone provides an accurate assessment of CpG-specific DNA methylation for EWAS studies but was unable to provide evidence of widespread associations between placental 5hmC and birthweight.