Is birth weight the major confounding factor in the study of gestational weight gain?: an observational cohort study.

BACKGROUND: Much interest has been focussed on both maternal obesity and gestational weight gain (GWG), particularly on their role in influencing birth weight (BW). Several large reviews have reported that excessive GWG is associated with an increase in BW. However recent large, well-designed, randomized controlled trials studying interventions aimed at reducing GWG have all consistently failed to show a reduction in BW despite achieving a reduction in GWG. The aim of this longitudinal prospective study was to examine the relationship between GWG and birth weight in women where GWG and Body Mass Index (BMI) were measured accurately in a strictly standardized way. METHODS: Women were enrolled at their convenience before 18 weeks gestation. Height and weight were measured accurately at the first antenatal visit and BMI calculated. Maternal weight was measured again after 37 weeks gestation. The weight of the baby was measured at birth. Relationships were tested using linear regression analysis, chi-squared tests and t-tests as appropriate. RESULTS: Of the 522 women studied, the mean BMI was 25.3 kg/m2 and 15.7% were obese. The mean BW at term was 3576 g (2160-5120) and 2.7% (n = 14) weighed ≥4500 g. The mean GWG overall was 12.3 kg (4.6 to 28.4) and GWG decreased as BMI increased. The mean GWG was less in obese women, at 8.7 kg (- 4.6 to 23.4), compared to non-obese,13.0 kg (0.6-28.4) (p < 0.001). Mean BW in obese women was 3630 g vs 3565 g in non-obese (p = 0.27). The total GWG correlated positively with BW (p < 0.001). When BW was subtracted from total GWG, GWG no longer correlated with BW (p = 0.12). CONCLUSIONS: The positive correlation between GWG in pregnancy and BW can be accounted for by the contribution of fetal weight to GWG antenatally without a contribution from increased maternal adiposity. There was a wide range of BW irrespective of the degree of GWG and obese women had a lower GWG than non-obese women. These findings help explain why Randomized Controlled Trials (RCTs) designed to reduce GWG have failed to decrease BW and suggest there is no causative link between excessive GWG and increased BW.

Structured promotion of breastmilk expression is associated with shortened hospitalisation for very preterm infants.

AIM: This study assessed neonatal outcomes following implementation of a structured, practical approach for promotion of breastmilk expression in mothers of very preterm infants. METHODS: A multidisciplinary team developed a protocol that focussed on the enhancement of expression of human milk by mothers of very preterm infants. A pre- and poststudy intervention was subsequently performed. The group of infants enrolled in this time period was compared to a pre-intervention group from 2010. Outcomes assessed included breastmilk expression, initiation of feeding, re-attainment of birthweight, attainment of full enteral feeding, the incidence of necrotising enterocolitis (NEC), sepsis and duration of hospitalisation. RESULTS: In total, 82 infants (39,43) were included. While there was no statistically significant difference in earlier initiation of enteral feeding with EBM (median = 2 days) nor earlier achievement of fully enteral feeding (median = 12 days), birthweight was regained earlier in the postintervention cohort (mean = 10.42 days; p = 0.038) and there was a reduced length of stay (mean = 50 days; p = 0.021). CONCLUSION: A structured, focussed, multimodal approach to enhance breastmilk production has shown potential for producing positive end outcomes, particularly, a significant reduction in duration of hospitalisation.

An estimation of periconceptional under-reporting of dietary energy intake.

BACKGROUND: The purpose of this cross-sectional study was to examine periconceptional misreporting of energy intake (EI) using the Willet food frequency questionnaire (WFFQ). METHODS: Women were recruited in the first trimester. Women completed a semi-quantitative WFFQ. Maternal body composition was measured using eight-electrode bioelectrical impedance analysis. Under-reporters were those whose ratio of EI to their calculated basal metabolic rate fell below the calculated plausible threshold for their physical activity category. RESULTS: The mean age was 30.1 ± 5.3 years (n = 524). The mean body mass index (BMI) was 25.4 ± 5.6 kg/m(2), and 16.6% were obese (BMI ≥ 30.0 kg/m(2)). Under-reported EI was observed in 122 women (23.3%) with no over-reporters in the sample. Under-reporters were younger (P < 0.001), less likely to have a normal BMI (P = 0.002) and more likely to be obese (P < 0.001) than plausible reporters. Under-reporters had higher percentage of body-fat and lower percentage of body fat-free mass (P < 0.001), were more likely to be at risk of relative deprivation (P = 0.001) and reported a higher percentage of EI from carbohydrate (P = 0.02) than plausible reporters. CONCLUSIONS: Observed differences between under-reporters and plausible reporters suggest that the exclusion of these under-reporters represents an important potential source of bias in obesity research among women in the periconceptional period.

Fetal subcutaneous tissue measurements in pregnancy as a predictor of neonatal total body composition.

OBJECTIVE: The purpose of this study was to examine the relationship between prenatal measures of subcutaneous tissue as surrogate markers of fetal nutritional status and correlate them with neonatal total body composition. METHODS: This prospective longitudinal study of 62 singleton pregnancies obtained serial biometry and subcutaneous tissue measurements at 28, 33 and 38 weeks gestation. These measurements were then correlated with neonatal body composition, which was analysed using the PEAPOD™ Infant Body Composition System (Cosmed USA, Concord, CA, USA). RESULTS: At 38 weeks gestation, fetal abdominal subcutaneous tissue (FAST) in millimetres was significantly associated with infant fat mass at delivery (+64 g per mm of FAST, p < 0.001). Thigh fat (TF) at 28 weeks gestation was associated with infant fat mass at delivery (+79 g/mm TF, p = 0.023). TF at 38 weeks gestation was associated with infant fat mass (+63/mm TF, p = 0.004). TF and FAST at 38 weeks were also predictive of both birth weight and increased abdominal circumference (AC) (p = 0.001) with FAST measurement predicting an additional 5.7 mm in AC per millimetre of FAST (p = 0.002) and TF predicting an additional 6.9 mm per mm of TF (p = 0.002). CONCLUSION: We believe that this study further validates the use of prenatal measures of subcutaneous tissue and may help to highlight fetuses at risk of newborn adiposity and metabolic syndrome.

The relationship between gestational weight gain and fetal growth: time to take stock?

The aim of this article is to review the current evidence on gestational weight gain (GWG). Maternal obesity has emerged as one of the great challenges in modern obstetrics as it is becoming increasingly common and is associated with increased maternal and fetal complications. There has been an upsurge of interest in GWG with an emphasis on the relationship between excessive GWG and increased fetal growth. Recent recommendations from the Institute of Medicine in the USA have revised downwards the weight gain recommendations in pregnancy for obese mothers. We believe that it is time to take stock again about the advice that pregnant women are given about GWG and their lifestyle before, during, and after pregnancy. The epidemiological links between excessive GWG and aberrant fetal growth are weak, particularly in obese women. There is little evidence that intervention studies decrease excessive GWG or improve intrauterine fetal growth. Indeed, there is a potential risk that inappropriate interventions during the course of pregnancy may lead to fetal malnutrition that may have adverse clinical consequences, both in the short- and long-term. It may be more appropriate to shift the focus of attention from monitoring maternal weight to increasing physical activity levels and improving nutritional intakes.

Birth weight and neonatal adiposity prediction using fractional limb volume obtained with 3D ultrasound.

INTRODUCTION: The objective of this investigation was to study fetal thigh volume throughout gestation and explore its correlation with birth weight and neonatal body composition. This novel technique may improve birth weight prediction and lead to improved detection rates for fetal growth restriction. MATERIALS AND METHODS: Fractional thigh volume (TVol) using 3D ultrasound, fetal biometry and soft tissue thickness were studied longitudinally in 42 mother-infant pairs. The percentages of neonatal body fat, fat mass and fat-free mass were determined using air displacement plethysmography. Correlation and linear regression analyses were performed. RESULTS: Linear regression analysis showed an association between TVol and birth weight. TVol at 33 weeks was also associated with neonatal fat-free mass. There was no correlation between TVol and neonatal fat mass. Abdominal circumference, estimated fetal weight (EFW) and EFW centile showed consistent correlations with birth weight. Thigh volume demonstrated an additional independent contribution to birth weight prediction when added to the EFW centile from the 38-week scan (p = 0.03). CONCLUSION: Fractional TVol performed at 33 weeks gestation is correlated with birth weight and neonatal lean body mass. This screening test may highlight those at risk of fetal growth restriction or macrosomia.

Diagnosing childhood-onset inborn errors of metabolism by next-generation sequencing.

BACKGROUND: Inborn errors of metabolism (IEMs) underlie a substantial proportion of paediatric disease burden but their genetic diagnosis can be challenging using the traditional approaches. METHODS: We designed and validated a next-generation sequencing (NGS) panel of 226 IEM genes, created six overlapping phenotype-based subpanels and tested 102 individuals, who presented clinically with suspected childhood-onset IEMs. RESULTS: In 51/102 individuals, NGS fully or partially established the molecular cause or identified other actionable diagnoses. Causal mutations were identified significantly more frequently when the biochemical phenotype suggested a specific IEM or a group of IEMs (p<0.0001), demonstrating the pivotal role of prior biochemical testing in guiding NGS analysis. The NGS panel helped to avoid further invasive, hazardous, lengthy or expensive investigations in 69% individuals (p<0.0001). Additional functional testing due to novel or unexpected findings had to be undertaken in only 3% of subjects, demonstrating that the use of NGS does not significantly increase the burden of subsequent follow-up testing. Even where a molecular diagnosis could not be achieved, NGS-based approach assisted in the management and counselling by reducing the likelihood of a high-penetrant genetic cause. CONCLUSION: NGS has significant clinical utility for the diagnosis of IEMs. Biochemical testing and NGS analysis play complementary roles in the diagnosis of IEMs. Incorporating NGS into the diagnostic algorithm of IEMs can improve the accuracy of diagnosis.