Noriko Sato

Background/Objectives: Although lifestyle patterns, including sleep and meal timing, have been associated with diet quality, previous studies have frequently relied on time-averaged data, which can obscure day-to-day intake variability. Using data from a food-logging mobile application, we aimed to elucidate the association between mealtime irregularity and nutrient intake variability. Furthermore, we explored whether the association between meal timing and diet quality differs depending on mealtime regularity. Methods: Chrononutritional characteristics were calculated for 742 female mobile application users who provided daily dietary records for approximately 1 month. Nutrient intake variability was evaluated using the coefficient of variation (CV). Diet quality was assessed based on the energy-adjusted ratio of nutrient intake to the reference values from the Dietary Reference Intakes for Japanese. Generalized additive models adjusted for age, body mass index, and physical activity were employed for analyzing associations. Results: Greater mealtime irregularity was associated with higher CVs in the daily intake of most nutrients investigated. Regarding diet quality, a marginal interaction was observed between mealtime regularity and dinner timing (p for interaction = 0.062). Specifically, the irregular mealtime group demonstrated a significant linear decline in diet quality with later dinner times (p for trend = 0.0112), whereas no significant decline was observed in the regular mealtime group (p for trend = 0.5219). Conclusions: Our findings suggest that mealtime regularity, alongside meal timing, is a significant factor involved in nutrient intake variability and diet quality, underscoring its significance as a health-related behavior in chrononutrition.

Background/Objectives: Discrepancies in mealtimes between weekdays and weekends—often referred to as “eating jetlag”—have been linked to a higher body mass index (BMI). However, in modern societies characterized by diverse work patterns, misalignment between mealtimes and the internal circadian rhythm may result not only from weekday–weekend differences but also from day-to-day variability. The aim of this study was to quantitatively assess and visualize daily mealtime variability over a 1-month period using food log data and to investigate the association between breakfast time irregularity and BMI. Methods: We conducted a retrospective, cross-sectional analysis using food log data (n = 1072; 742 women and 360 men) extracted from a popular Japanese food-logging mobile application. Mealtime irregularity was quantified using composite phase deviation (CPD). Data were stratified by sex and age tertile. Results: Approximately 18% of participants (women and men) exhibited irregular breakfast timing (CPD > 1 h). Multivariate regression analysis revealed that an evening-type chronotype was primarily associated with BMI among younger women, whereas breakfast time irregularity was associated with BMI among older women. Conclusions: Our findings suggest that daily mealtime variability is an additional chrono-nutritional factor associated with BMI. Furthermore, the chrono-nutritional factors most strongly associated with BMI may differ by age.

The optimal range of gestational weight gain (GWG) was recently raised in Japan. This may help reduce small-for-gestational-age (SGA) infants, but may also increase large-for-gestational-age (LGA) infants. This study performed hypothetical experiments to determine effective GWG advice based on quantile regression analysis. In a total of 354,401 singleton pregnancies registered in the perinatal database of the Japan Society of Obstetrics and Gynecology (2013–2017), the proportions of SGA and LGA were 9.33% and 11.13%, respectively. Using regression coefficients of GWG across the birth weight-for-gestational-age quantile distribution, we analyzed changes in their proportions by simulating a uniform 3-kg extra increase in GWG or an increase or decrease based on GWG adequacy. A hypothetical experiment of a uniform increase in GWG resulted in SGA and LGA proportions of 7.26% (95% confidence interval 7.15–7.36) and 14.51% (14.37–14.66), respectively. By contrast, assuming a 3-kg increase in women with inadequate GWG and a 3-kg decrease in women with excessive GWG resulted in SGA and LGA proportions of 8.42% (8.31–8.54) and 11.50% (11.37–11.62), respectively. Our real-world data analysis suggests that careful adjustment of GWG based on GWG adequacy will be effective in optimizing infant birth weight in Japan

Objective: The optimal range of gestational weight gain (GWG) was recently raised in Japan. Considering that the effect of GWG on birth weight varies by quantile, this study performed hypothetical experiments to determine effective GWG advice to reduce small-for-gestational-age (SGA) infants while limiting the increase in large-for-gestational-age (LGA) infants. Design: Retrospective cohort study. Setting: The Japanese Society of Obstetrics and Gynecology nationwide perinatal database, 2013–2017. Population: A cohort of 354,401 primiparous singleton pregnancies. Methods: The association between GWG and birth weight for gestational age was analyzed using a quantile regression model. Based on the results, we estimated how hypothetical strategies targeting women of inadequate or excessive GWG might influence the proportions of SGA and LGA compared with a body mass index (BMI)-based uniform strategy. Main outcome measure: Birth weight for gestational age. Results: The estimated proportions of SGA and LGA in the study population were 9.33 and 11.13, respectively, whereas those in the BMI-based uniform strategy, which assumed a 3-kg increase in GWG for women with BMI < 25 kg/m ² , were 7.26 (95% confidence interval: 7.15–7.36) and 14.51 (14.37–14.66). By contrast, assuming a 3-kg increase and a 3-kg decrease in women with inadequate and excessive GWG, the estimated proportions of SGA and LGA were 8.42 (8.31–8.54) and 11.50 (11.37–11.62), respectively. Conclusions: When providing GWG advice, not only increasing GWG according to prepregnancy BMI, but also determining GWG adequacy and decreasing it when excessive GWG is observed, may be effective for optimizing birth outcomes.

Maternal underweight and inadequate gestational weight gain (GWG) are problems in Japan. However, increases in food intake aimed at weight gain alone are not sufficient for mother–child health. This study assessed diet quality based on the 3-day dietary records of pregnant women in an urban area of Japan in order to show the importance of evaluating diet quality, using the Nutrient-Rich Food Index 9.3 (NRF9.3), which is one metric based on nutrition profiling, and the Japanese Food Guide Spinning Top (JFGST). After excluding misreporters of energy intake, we stratified women (n = 91) by pre-pregnancy body mass index (BMI) and determined energy intake, diet quality status, and their relationship with GWG. Intakes of carbohydrate-containing staple foods, vegetable dishes, and fruit were insufficient regardless of BMI. Most of the underweight women with inadequate GWG had insufficient energy intake but high diet quality, as assessed by NRF9.3. In contrast, most women who consumed energy within the recommended range had low diet quality and gained weight at inappropriate levels. These results highlight the importance for pregnant Japanese women to maintain diet quality through a nutrient-dense diet, while simultaneously increasing energy intake after evaluation of their individual diet quality.

Placenta-derived extracellular vesicles and their cargoes, especially microRNAs (EV-miRNAs), may contribute to fetal and placental development. During pregnancy, the levels of several maternal bloo...

Background: Low birth weight (LBW) and fetal growth restriction are associated with the development of cardio-metabolic diseases later in life. A recent Mendelian randomization study concluded that the susceptibility of LBW infants to develop hypertension during adulthood is due to the inheritance of hypertension genes from the mother and not to an unfavorable intrauterine environment. Therein, a negative linear association has been assumed between genetically estimated maternal blood pressure (BP) and birth weight, while the observed relationship between maternal BP and birth weight is substantially different from that assumption. As many hypertension genes are likely involved in vasculature development and function, we hypothesized that BP-increasing genetic variants could affect birth weight by reducing the growth of the placenta, a highly vascular organ, without overtly elevating the maternal BP. Methods: Using a birth cohort in the Japanese population possessing time-series fetal growth velocity data as a target and a GWAS summary statistics of BioBank Japan as a base data, we performed polygenic score (PGS) analyses for systolic BP (SBP), diastolic BP, mean arterial pressure, and pulse pressure. A causal mediation analysis was performed to assess the meditation effect of placental weight on birth weight reduced by maternal BP-increasing PGS. Maternal genetic risk score constituted of only “vasculature-related” BP single nucleotide polymorphisms (SNPs) was constructed to examine the involvement of vascular genes in the mediation effect of placental weight. We identified gestational week in which maternal SBP-increasing PGS significantly decreased fetal growth velocity. Results: We observed that maternal SBP-increasing PGS was negatively associated with offspring birth weight. A causal mediation analysis revealed that a large proportion of the total maternal PGS effect on birth weight was mediated by placental weight. The placental mediation effect was remarkable when genetic risk score was constituted of “vasculature-related” BP SNPs. The inverse association between maternal SBP PGS and fetal growth velocity only became apparent in late gestation. Conclusions: Our study suggests that maternal hypertension genes are strongly associated with placental growth and that fetal growth inhibition is induced through the intrauterine environment established by the placenta.

The maternal diet can potentially influence the life-course health of the child. A poor-quality maternal diet creates nutrient deficiencies and affects immune–metabolic regulation during pregnancy. The nutrient-based overall dietary quality can be assessed using the Nutrient-Rich Food Index 9.3 (NRF9.3), which measures adherence to the national reference daily values of nutrient intake. Pro- and anti-inflammatory nutrient intake can be assessed using the energy-adjusted dietary inflammatory index (E-DII), a comprehensive index of diet-derived inflammatory capacity. Using these indices, we assessed the overall dietary quality and inflammatory potential of pregnant women during mid-gestation in an urban area of Japan (n = 108) and found that there was a strong inverse correlation between the NRF9.3 and E-DII scores. Comparison of the scores among the tertiles of NRF9.3 or E-DII indicated that dietary fiber, vitamin C, vitamin A, and magnesium mainly contributed to the variability of both indices. Intake of vegetables and fruits was positively associated with high NRF9.3 scores and negatively associated with high E-DII scores, after adjustment for maternal age, pre-pregnancy body mass index, and educational level. Consistent with the previous studies that used dietary pattern analysis, this study also demonstrated that vegetables and fruits were the food groups chiefly associated with high dietary quality and low inflammatory potential among pregnant Japanese women.

Low birth weight is associated with the development of cardio-metabolic diseases later in life1-4. A recent Mendelian Randomization Study concluded that the susceptibility of low-birth-weight infants to develop hypertension during adulthood is due to the inheritance of hypertension genes from the mother, and not to an unfavorable intrauterine environment5. Therein, it has been assumed that low birth weight is caused by maternal hypertension5,6, although there is no evidence to support such a linear relationship. In the present study, we have noted that most of blood pressure SNPs are related to vascular regulation7-9 and found that the relationship between maternal blood pressure-increasing polygenic score and reduction of offspring birth weight is mediated by a reduced growth of the placenta but not by the mother's high blood pressure. This suggests that the risk of hypertension of low-birth-weight infants may result from a poor placental environment.

Background: Japan has an exceptionally high proportion of low-weight births and underweight women. It has been suggested that an appropriate increase in gestational weight gain (GWG) for underweight women will help to prevent low birth weight. The current strategy aims to raise the desired value of GWG equally for all pregnant women within the underweight category. However, it remains elusive whether or not the relationship between GWG and birth weight for gestational age (BW/GA) are uniformly equivalent for all the women.Methods: We performed a retrospective cohort analysis of women who delivered their newborns at Tokyo Medical and Dental University Hospital from 2013 to 2017. First, in order to examine the direct effect of an increase or decrease in GWG on BW/GA, we analyzed the correlation between inter-pregnancy differences in GWG and BW/GA using a sub-cohort of women who experienced two deliveries during the study period (n = 75). Second, we dichotomized the main cohort (n = 1114) according to BW/GA to verify our hypothesis that the correlation between GWG and BW/GA differs depending on the size of the newborn.Results: The inter-pregnancy difference in BW/GA was not correlated with that of GWG. However, the correlation between BW/GA of siblings was high (r = 0.63,p = 1.9 × 10^− 9). The correlation between GWG and BW/GA in women who delivered larger-sized newborns was higher (r = 0.17,p = 4.1 × 10^− 5) than that in women who delivered smaller-sized newborns (r = 0.099,p = 1.9 × 10^− 2). This disparity did not change after adjustment for pre-pregnancy BMI. The mean birth weight in the dichotomized groups corresponded to percentile 52.0 and 13.4 of the international newborn size assessed by INTERGROWTH-21st standards.Conclusions: In our study, GWG was positively correlated with BW/GA for heavier neonates whose birth weights were similar to the average neonatal weight according to world standards. However, caution might be required for low-birth-weight neonates because increased GWG does not always result in increased birth weight.