Mendelian randomization suggests that head circumference, but not birth weight and length, associates with intelligence

Multimodal machine learning for modeling infant head circumference, mothers' milk composition, and their shared environment

Links between human milk (HM) and infant development are poorly understood and often focus on individual HM components. Here we apply multi-modal predictive machine learning to study HM and head circumference (a proxy for brain development) among 1022 mother-infant dyads of the CHILD Cohort. We integrated HM data (19 oligosaccharides, 28 fatty acids, 3 hormones, 28 chemokines) with maternal and infant demographic, health, dietary and home environment data. Head circumference was significantly predictable at 3 and 12 months. Two of the most associated features were HM n3-polyunsaturated fatty acid C22:6n3 (docosahexaenoic acid, DHA; p = 9.6e-05) and maternal intake of fish (p = 4.1e-03), a key dietary source of DHA with established relationships to brain function. Thus, using a systems biology approach, we identified meaningful relationships between HM and brain development, which validates our statistical approach, gives credence to the novel associations we observed, and sets the foundation for further research with additional cohorts and HM analytes.

Exposure to ultra-processed foods during pregnancy and ultrasound fetal growth parameters

Periconceptional maternal ultra-processed food (UPF) consumption impairs embryonic growth. Impacts of exposure to UPF on distinct components of fetal growth in late pregnancy are unknown. We investigated the influence of frequency of UPF consumption during pregnancy on fetal head circumference (HC), abdominal circumference (AC) and femur length (FL). This study included 417 live-born singleton pregnancies prospectively followed-up since the antenatal period in the MINA-Brazil Study, with an available ultrasound scan at >24 gestational weeks. Frequency of food groups consumption in the previous month was categorised as no/monthly, weekly or daily. Ultrasound scans were conducted at 27·8 (sd: 1·7) gestational weeks. HC, AC and FL z-scores were calculated for gestational age using the INTERGROWTH-21st Project standards. Simultaneous-quantile regression models were fitted at the 10th, 50th and 90th percentiles of the distribution of each ultrasound parameter according to UPF consumption, with adjustment for potential confounders. Participants were aged on average 24·7 (sd: 6·5) years, 44·8 % were primiparous, and 26·9 % and 24·9 %, respectively, had weekly and daily UPF consumption. Compared with no/monthly intake, daily UPF consumption impaired HC across its distribution, with significant effect sizes varying from -0·24 to -0·40 z-score. Weekly UPF consumption decreased HC at the 90th percentile by -0·39 z-score (95 % CI: -0·78, -0·01) and FL at the 50th percentile by -0·32 z-score (95 % CI: -0·60, -0·04). No association was noted with AC. Frequency of UPF consumption was negatively associated with skeletal components of fetal growth in late pregnancy. Infant body composition may benefit from healthy food practices since pregnancy.

Birth size, school performance and family social position: a study of 650,000 children

BACKGROUND

Low birth weight (BW) is associated with lower cognitive functioning, but less is known of these associations across the full range of the BW distribution and its components. We analyzed how BW, birth length (BL) and birth ponderal index (BPI, kg/m3) are associated with school performance and how childhood family social position modifies these associations.

METHODS

Medical birth records of all Finnish children born in 1987-1997 were linked to school performance records at 16 years of age (N = 642,425). We used population averaged and within-siblings fixed-effects linear regression models.

RESULTS

BL showed a linear and BW a curvilinear association with school performance whereas for BPI the association was weak. The strongest association was found for BL explaining 0.08% of the variation in school performance in boys and 0.14% in girls. Demographic, gestational and social factors partly explained these associations. Similar but weaker associations were found within sibships. The association of BL with school performance was stronger at lower levels of family social position.

CONCLUSION

BL shows a linear association with school performance and can explain more school performance variation than BW. At the population level, BL can offer useful information on intrauterine environmental factors relevant for cognitive performance.

IMPACT

Birth length is linearly associated with school performance in late adolescence and explains a larger proportion of school performance variation than birth weight. The association between birth length and school performance is stronger in families with lower socio-economic position. At the population level, birth length can offer information on the intrauterine environment relevant for later cognitive performance.

The association between maternal healthy lifestyle factors during pregnancy and the neonatal anthropometric indicators based on a prospective cohort study

BACKGROUND AND OBJECTIVES

We aimed to evaluate the associations between a combined healthy lifestyle during the second and third trimesters and offspring anthropometric outcomes in China.

METHODS AND STUDY DESIGN

We examined these associations among 548 participants from nine community health centers and three hospitals in the North China cohort. A pregnant women's healthy lifestyle score (HLS) was constructed based on six lifestyle factors: smoking, alcohol consumption, physical activity, sedentary behavior, diet, and gestational weight gain. Anthropometric indicators at birth like birth weight (BW), head circumference (HC), and birth length (BL) were collected, and weight to head circumference ratio (WHC, kg/m), body mass index (BMI, kg/m2) and Ponderal Index (PI, kg/m3) were calculated. Multivariate linear and logistic regression models were used to examine the effects of HLS during the second and third trimesters on anthropometric outcomes at birth, respectively.

RESULTS

In fully adjusted models, we found a negative association between second and third-trimester HLS and offspring HC and a positive relationship between second-trimester HLS and BL (p<0.05). Neonates with mothers in the highest HLS tertile had a 5.6% relatively lower HC and 2.3% relatively longer body length than women in the lowest tertile. Each additional unit in third-trimester HLS had an associated decrease in HC by 0.96 cm. None of the associations between HLS and BW, WHC, BMI, and PI of offspring were observed.

CONCLUSIONS

A healthy lifestyle score may significantly impact offspring head circumference and body length, supporting the important role of healthy lifestyles in improving the health of offspring.

Neurodevelopment and physical measurements in infants with birthweight of 500 grams or less

BACKGROUND

In infants born weighing ≤500 g, little has been studied about the association between neurodevelopmental prognosis and growth. This study aimed to evaluate the association between neurodevelopmental impairment (NDI) and z-scores of physical measurements in infants born weighing ≤500 g.

METHODS

A single-center, retrospective cohort study in a level IV neonatal intensive care unit in Japan. Infants born weighing ≤500 g between 2010 and 2019 were eligible. Z-scores in weight, length/height, and head circumference at birth, due date (or discharge), 6 and 18 months of corrected age, and 3 years of age were compared between infants with and without NDI at 3 years of age. Three infants with severe intraventricular hemorrhage or periventricular leukomalacia were excluded from the comparison analyses. NDI was defined as having a developmental quotient of ≤70, cerebral palsy, visual impairment, or hearing impairment.

RESULTS

Of 22 eligible infants, the incidence of NDI at 3 years of age was 54.5%. The z-score was significantly smaller in the NDI group (n = 10) than that in the non-NDI group (n = 9) in head circumference at birth (median, -1.94 vs. -0.75; Z = 0.54; p = 0.020), and in height at 18 months of corrected age (median, -2.84 vs. -1.79; Z = 0.58; p = 0.013) and 3 years of age (median, -2.02 vs. -1.21; Z = 0.47; p = 0.046).

CONCLUSIONS

NDI at 3 years of age was associated with a small head circumference z-score at birth, height at 18 months of corrected age, and height at 3 years of age in infants born weighing ≤500 g.

Dynamics of human milk oligosaccharides in early lactation and relation with growth and appetitive traits of Filipino breastfed infants

Human milk oligosaccharides play a key role in the maturation of the infant gut microbiome and immune system and are hypothesized to affect growth. This study examined the temporal changes of 24 HMOs and their associations to infant growth and appetitive traits in an exploratory, prospective, observational, study of 41 Filipino mother-infant dyads. Exclusively breastfed, healthy, term infants were enrolled at 21-26 days of age (≈ 0.75 mo) and followed for 6 months. Infant growth measures and appetitive traits were collected at visit 1 (V1) (≈ 0.75 mo), V2 (≈ 1.5 mo), V3 (2.5 mo), V4 (2.75 mo), V5 (4 mo), and V6 (6 mo), while HMOs were measured at V1, V2, V3 and V5. Overall exposure to each HMO was summarized as area under the curve from baseline to 4 months of age and examined in association with each measure of growth at 6 months using linear regression adjusted for maternal age at birth, infant sex, birth weight, and mode of delivery. We saw modest associations between several HMOs and infant growth parameters. Our results suggest that specific HMOs, partly as proxy for milk groups (defined by Secretor and Lewis status), may be associated with head circumference and length, increasing their relevance especially in populations at the lower end of the WHO growth curve. We did not identify the same HMOs associated with infant appetitive traits, indicating that at least in our cohort, changes in appetite were not driving the observed associations between HMOs and growth.Clinical trial registration: NCT03387124.

Mendelian randomization suggests that head circumference, but not birth weight and length, associates with intelligence

INTRODUCTION

Birth parameters have long been reported to have a role in human intelligence. However, the causalities reported in previous observational studies were controversial. Our study aims to provide an unbiased investigation of the causal associations between birth parameters and human intelligence using the Mendelian randomization (MR) approach.

METHODS

Genetic instrumental variables for MR analyses were extracted from large genome-wide association studies of infant head circumference (N = 10,768), birth length (N = 28,489), and birth weight (N = 321,223). Data for intelligence were obtained from a meta-analysis of genome-wide association studies of 269,867 individuals of the European ancestry. Primary MR analysis was performed using the standard inverse-variance weighted method, and sensitivity analyses were performed using the weighted median, MR-Egger, and MR-PRESSO methods.

RESULTS

Using 10 single nucleotide polymorphisms as instrumental variables, we found that 1 standard deviation increase in infant head circumference was associated with 0.14-fold higher scores in intelligence tests (β = 0.14, 95% confidence interval: 0.09 to 0.18, P_IVW =2.05 × 10^-9 ). The causal relationship was robust when sensitivity analyses were performed. However, birth length and birth weight had no significant associations with intelligence.

CONCLUSION

Our findings suggested infant head circumference, but not birth weight and length were associated with intelligence, which might indicate that brain development rather than general fetal growth was responsible for the development of intelligence.