Effects of ambient air pollution on the risk of small- and large-for-gestational-age births: an analysis using national birth data in Japan.

OBJECTIVES: Small-for-gestational-age (SGA) and large-for-gestational-age (LGA) births are major adverse birth outcomes related to newborn health. In contrast, the association between ambient air pollution levels and SGA or LGA births has not been investigated in Japan; hence, the purpose of our study is to investigate this association. METHODS: We used birth data from Vital Statistics in Japan from 2017 to 2021 and municipality-level data on air pollutants, including nitrogen dioxide (NO2), sulfur dioxide (SO2), photochemical oxidants, and particulate matter 2.5 (PM2.5). Ambient air pollution levels throughout the first, second, and third trimesters, as well as the whole pregnancy, were calculated for each birth. The association between SGA/LGA and ambient levels of the air pollutants was investigated using crude and adjusted log-binomial regression models. In addition, a regression model with spline functions was also used to detect the non-linear association. RESULTS: We analyzed data from 2,434,217 births. Adjusted regression analyses revealed statistically significant and positive associations between SGA birth and SO2 level, regardless of the exposure period. Specifically, the risk ratio for average SO2 values throughout the whole pregnancy was 1.014 (95% confidence interval [CI] 1.009, 1.019) per 1 ppb increase. In addition, regression analysis with spline functions indicated that an increase in risk ratio for SGA birth depending on SO2 level was linear. Furthermore, statistically significant and negative associations were observed between LGA birth and SO2 except for the third trimester. CONCLUSIONS: It was suggested that ambient level of SO2 during the pregnancy term is a risk factor for SGA birth in Japan.

Exploring the association between non-regular employment and adverse birth outcomes: an analysis of national data in Japan.

Background: As few studies have explored the association between non-regular or precarious employment in parents and adverse birth outcomes, this study aimed to investigate this association using national data in Japan. Methods: This study utilized the census data from 2020 and birth data from the vital statistics in 2021 and 2022 in the analysis. Adverse birth outcomes, including preterm birth, term low birth weight (TLBW), and small-for-gestational-age, were examined. Data linkage was conducted between birth data and census data to link parental employment statuses and educational attainments with birth data. Rates of adverse birth outcomes were calculated for each parental employment status. Additionally, regression analysis was used to determine adjusted risk ratios (RRs) of parental employment statuses for each birth outcome. Results: After data linkage, 334,110 birth records were included in the statistical analysis. Rates for non-regular workers were consistently higher than those for regular workers across all adverse birth outcomes for maternal employment status. Results of regression analyses indicated that the risks of preterm birth for non-regular workers were statistically significantly higher than those for regular workers, both in mothers and fathers with a RR (95% confidence intervals [CIs]) of 1.053 (1.004-1.104) and 1.142 (1.032-1.264), respectively. Furthermore, the risk of TLBW birth for non-regular workers was statistically significantly higher than that for regular workers in fathers (RR [95% CI]: 1.092 [1.043-1.143]). Conclusions: Our findings demonstrate that non-regular workers have a higher risk of some adverse birth outcomes compared to regular workers.

A nationwide survey of facial onset sensory and motor neuronopathy in Japan.

The epidemiology and etiology of facial onset sensory and motor neuronopathy (FOSMN), a rare syndrome that initiates with facial sensory disturbances followed by bulbar symptoms, remain unknown. To estimate the prevalence of FOSMN in Japan and establish the characteristics of this disease, we conducted a nationwide epidemiological survey. In the primary survey, we received answers from 604 facilities (49.8%), leading to an estimated number of 35.8 (95% confidential interval: 21.5-50.2) FOSMN cases in Japan. The secondary survey collected detailed clinical and laboratory data from 21 cases. Decreased or absent corneal and pharyngeal reflexes were present in over 85% of the cases. Electrophysiological analyses detected blink reflex test abnormalities in 94.1% of the examined cases. Immunotherapy was administered in 81% of cases and all patients received intravenous immunoglobulin. Among them, 35.3% were judged to have temporary beneficial effects evaluated by the physicians in charge. Immunotherapy tended to be effective in the early stage of disease. The spreading pattern of motor and sensory symptoms differed between cases and the characteristics of the motor-dominant and sensory-dominant cases were distinct. Cases with motor-dominant progression appeared to mimic amyotrophic lateral sclerosis. This is the first nationwide epidemiological survey of FOSMN in Japan. The clinical course of FOSMN is highly variable and motor-dominant cases developed a more severe condition than other types of cases. Because clinical interventions tend to be effective in the early phase of the disease, an early diagnosis is desirable.

The effect of educational attainment on birthrate in Japan: an analysis using the census and the vital statistics from 2000 to 2020.

BACKGROUND: In Japan, difference in birth rates depending on educational attainment has not been investigated. This study aimed to reveal birth rates in Japan depending on the highest level of educational attainment and their trends over the years using nationwide government statistics data. METHODS: Individual-level data from Vital Statistics and the Census from 2000, 2010, and 2020 were used for birth and population data, respectively. Data linkage was conducted for males and females in the Census and fathers and mothers in the Vital Statistics using information about gender, household, nationality, marital status, birth year, birth month, prefecture, and municipality for individuals. The birth rate was calculated by gender, a five-year age group, the highest level of educational attainment achieved, and year. In addition, the slope index of inequality (SII) and relative index of inequality (RII) were calculated to evaluate the degree of inequality in birth rates, depending on the educational attainment. RESULTS: Birth rates were higher in persons with lower educational attainment compared to those with a higher educational attainment among males and females in their twenties, while they tended to be higher in persons with higher educational attainment among those in their thirties and forties. Additionally, an increase in the birth rate from 2000 to 2020 was the largest in university graduates among males aged 25-49 years and women aged 30-49 years, and a decrease in the birth rate was the smallest in university graduates among males and females aged 20-24 years. As a result, SII and RII increased from 2000 to 2020 among males and females in their thirties and forties. CONCLUSIONS: In conclusion, persons with higher educational attainment tended to have a relatively favorable trend in the birth rate compared with persons with lower educational attainment in recent decades. It suggested that enhanced administrative support for individuals with lower educational attainment or lower socioeconomic status may be required to ameliorate the declining birth rate in Japan.

Difference in risk of preterm and small-for-gestational-age birth depending on maternal occupations in Japan.

OBJECTIVES: In this study, an association between the mother's occupations with preterm and small-for-gestational-age (SGA) births was investigated using national data in Japan, and individual-level birth data from the Report of Vital Statistics: Occupational and Industrial Aspects in the 2015 fiscal year were used. Preterm and SGA birth rates were calculated for each of infant characteristics, and relative risk of each type of maternal occupations (categorized into 12 types) for the outcomes was estimated using a log binomial regression model. RESULTS: Data of 997,600 singleton births were analyzed. Among maternal occupations, preterm birth rate was highest among carrying, cleaning, packaging, and related workers (5.65%) and lowest among security workers (4.24%). SGA birth rate was highest among manufacturing process workers (5.91%) and lowest among security workers (4.00%). We found significantly elevated risks for preterm birth among manufacturing process workers compared with unemployed mothers, and significantly elevated risks for SGA birth compared with unemployed mothers were observed among sales workers, service workers, and manufacturing process workers. In contrast, security workers had a significantly decreased risk for SGA birth compared with unemployed mothers.

Analysis of the Incidence of Macrosomia in Japan by Parental Nationalities at 5-year Intervals From 1995 to 2020.

OBJECTIVES: We investigated trends in the incidence rate of macrosomia and its association with parental nationalities using Vital Statistics data in Japan. METHODS: We used singleton birth data every 5 years from 1995 to 2020. The incidence rate of macrosomia was calculated according to specific attributes (maternal age, infant's sex, parental nationalities, parity, and household occupation) over time (years). In addition, a log-binomial model was used to investigate the relationship between the incidence of macrosomia and the attributes. This study compared Korea, China, the Philippines, Brazil, and other countries with Japan in terms of parental nationalities. "Other countries" indicates countries except for Japan, Korea, China, the Philippines, and Brazil. RESULTS: The study included 6 180 787 births. The rate of macrosomia in Japan decreased from 1.43% in 1995 to 0.88% in 2020, and the decrease was observed across all parental nationalities. The rates for Japanese parents were the lowest values among parental nationalities during the timespan investigated. Multivariate regression analysis showed that mothers from Korea, China, the Philippines, Brazil, and other countries had a significantly higher risk of macrosomia than those from Japan (risk ratio, 1.91, 2.82, 1.59, 1.74, and 1.64, respectively). Furthermore, fathers from China, the Philippines, Brazil, and other countries had a significantly higher risk of macrosomia than those from Japan (risk ratio, 1.66, 1.38, 1.88, and 3.02, respectively). CONCLUSIONS: The rate of macrosomia decreased from 1995 to 2020 in Japan for parents of all nationalities, and the risk of macrosomia incidence was associated with parental nationality.

Association between infant mortality and parental educational level: An analysis of data from Vital Statistics and Census in Japan.

This study investigated the association between parental educational level and infant mortality using data from Vital Statistics and Census in Japan. We used the Census data in 2020 and birth and mortality data from the Vital Statistics from 2018 to 2021 in Japan. Data linkage was conducted between birth data and the Census to link the educational level with parents for birth data and between the birth data and mortality data to identify births that resulted in infant mortality. Four educational levels were compared: "junior high school," "high school," "technical school or junior college," and "university." A multivariate logistic regression model was used to investigate an association between parental educational level and infant mortality using other risk factors as covariates. After the data linkage, data on 890,682 births were analyzed. The proportion of junior high school or high school graduates was higher among fathers and mothers for births with infant mortality compared with that among those for births without infant mortality; in contrast, the proportion of university graduates was lower for births with infant mortality than those without infant mortality. Regression analysis showed that mothers with junior high school or high school graduates were significantly and positively associated with infant mortality compared with those with university graduates. As a conclusion, lower educational level in mothers was positively associated with infant mortality, and it was shown that a difference in infant mortality depending on parental educational level existed in Japan.

Correction: Okui, T. Analysis of an Association between Preterm Birth and Parental Educational Level in Japan Using National Data. Children 2023, 10, 342.

In the original publication [...].

Association of maternal nationality with preterm birth and low birth weight rates: analysis of nationwide data in Japan from 2016 to 2020.

BACKGROUND: The rate of low birth weight or preterm birth is known to vary according to the birth place of mothers. However, in Japan, studies that investigated the association between maternal nationalities and adverse birth outcomes are few. In this study, we investigated the association between maternal nationalities and adverse birth outcomes. METHODS: We obtained live birth data from the Vital Statistics 2016-2020 of the Ministry of Health, Labour, and Welfare. We used data on maternal age, sex, parity, gestational age, birth weight, number of fetuses, household occupation, paternal nationality, and maternal nationality for each infant. We compared the rates of preterm birth and low birth weight at term among mothers whose nationalities were Japan, Korea, China, Philippines, Brazil, and other countries. Log binomial regression model was used to investigate the association between maternal nationality and the two birth outcomes using the other infants' characteristics as covariates. RESULTS: In the analysis, data on 4,290,917 singleton births were used. Mothers from Japan, Korea, China, the Philippines, Brazil, and other nations had preterm birth rates of 4.61%, 4.16%, 3.97%, 7.43%, 7.69%, and 5.61%, respectively. The low birth weight rate among Japanese mothers was 5.36% and was the highest among the maternal nationalities. Regression analysis showed that the relative risk for preterm birth among Filipino, Brazilian, and mothers from other countries (1.520, 1.329, and 1.222, respectively) was statistically significantly higher compared with Japanese mothers. In contrast, the relative risk for Korean and Chinese mothers (0.870 and 0.899, respectively) was statistically significantly lower compared with Japanese mothers. Mothers from Korea, China, the Philippines, Brazil, and other nations had a relative risk for low birth weight that was statistically significantly lower than that of Japanese mothers (0.664, 0.447, 0.867, 0.692, and 0.887, respectively). CONCLUSIONS: Support for mothers from the Philippines, Brazil, and other countries are necessary to prevent preterm birth. A future study is necessary to investigate the differences in characteristics among mothers of different nationalities in order to uncover the reason for the high risk for low birth weight among Japanese mothers.

Transcatheter arterial steroid injection therapy improves the prognosis of patients with acute liver failure.

Acute liver failure (ALF) is a disorder defined by coagulopathy and encephalopathy with a poor prognosis. No effective therapies have been established except for liver transplantation. We previously reported a subgroup of patients with acute liver injury who developed microcirculatory disturbance. We also established and reported transcatheter arterial steroid injection therapy (TASIT) as a new treatment of ALF. Here, we analyze the effectiveness of TASIT in a larger cohort and evaluate the impact on ALF patients with or without microcirculatory disturbance. We conducted a single-center retrospective study to evaluate the effectiveness of TASIT in patients with ALF admitted at Kyushu University Hospital between January 2005 and March 2018. TASIT is performed by injecting methylprednisolone via the proper hepatic artery for 3 days. One hundred ninety-4 patients with ALF were enrolled and analyzed in this study. Of the 87 patients given TASIT, 71 (81.6%) recovered without any complications and 16 (18.4%) died or underwent liver transplantation. Of the 107 patients not administered TASIT, 77 (72.0%) recovered and 30 (28.0%) progressed to irreversible liver failure. In the high-lactate dehydrogenase subgroup, 52 (86.7%) of the 60 patients with TASIT recovered, and the survival rate was significantly higher than that in patients who did not receive TASIT. Multivariate regression analysis revealed that the TASIT procedure was one of the significant prognostic factors in the high-lactate dehydrogenase subgroup and was significantly associated with prothrombin activity percentage improvement. TASIT is an effective treatment for patients with ALF, especially in those with microcirculatory disturbance.

Analysis of an Association between Preterm Birth and Parental Educational Level in Japan Using National Data.

Preterm birth rate depending on parental educational level in recent years has not been surveyed in Japan. In this study, we showed the trend in preterm birth rate depending on parental educational level from 2000 to 2020 by linking data from the Census regarding individuals' educational level and parents in birth data of the vital statistics. Four types of parental educational level, namely junior high school, high school, technical school or junior college, and university or graduate school, were compared. Slope and relative indexes of inequality for preterm birth by educational level were computed by binomial models. Data on 3,148,711 births and 381,129,294 people were used in the analysis, and data on 777,086 singleton births were used after data linkage. The preterm birth rate (%) for junior high school graduate mothers and fathers was 5.07 and 5.21 in 2020, respectively. Contrarily, the preterm birth rate (%) for parents who graduated from a university or graduate school was 4.24 for mothers and 4.39 for fathers, and the rate tended to increase as educational level decreased, irrespective of parental gender. Results of inequality indexes showed that a statistically significant inequality by parental educational level persisted from 2000 to 2020.

Analysis of association between low birth weight and socioeconomic deprivation level in Japan: an ecological study using nationwide municipal data.

BACKGROUND: Several international studies have indicated an association between socioeconomic deprivation levels and adverse birth outcomes. In contrast, those investigating an association between socioeconomic status and low birth weight using nationwide data are limited in Japan. In this study, we investigated an association between municipal socioeconomic deprivation level and low birth weight by an ecological study. METHODS: Nationwide municipal-specific Vital Statistics data from 2013 to 2017 were used. We calculated the low birth weight rate and standardized incidence ratio (SIR) for low birth weight for each municipality and plotted them on a Japanese map. Furthermore, the correlation coefficient between them and the deprivation level were calculated. In addition, a spatial regression model including other municipal characteristics was used to investigate an association between low birth weight and the deprivation level. RESULTS: Municipalities with relatively high SIR for low birth weight were dispersed across all of Japan. The correlation coefficient between the socioeconomic deprivation level and low birth weight rate was 0.196 (p-value < 0.001) among municipalities, and that between the socioeconomic deprivation level and the SIR for low birth weight was 0.260 (p-value < 0.001). In addition, the spatial regression analysis showed the deprivation level was significantly and positively associated with low birth weight. CONCLUSIONS: The socioeconomic deprivation level and low birth weight were positively associated, and a further study using individual data is warranted to verify reasons for the association.

Increased risk of metastasis in patients with incidental use of renin-angiotensin system inhibitors: a retrospective analysis for multiple types of cancer based on electronic medical records.

Renin-angiotensin system inhibitors have been shown to prevent cancer metastasis in experimental models, but there are limited data in clinical studies. We aimed to explore whether renin-angiotensin system inhibitors administered during the period of cancer resection can influence the subsequent development of metastasis by analyzing multiple individual types of primary cancers. A total of 4927 patients who had undergone resection of primary cancers at Kyushu University Hospital from 2009 to 2014 were enrolled and categorized into 3 groups based on the use of antihypertensive drugs: renin-angiotensin system inhibitors, other drugs, and none. Cumulative incidence functions of metastasis, treating death as a competing risk, were calculated, and the difference was examined among groups by Gray's test. Fine and Gray's model was employed to evaluate multivariate-adjusted hazards of incidental metastasis. In the multivariate-adjusted analysis, patients with skin and renal cancers showed statistically higher risks of metastasis with the use of renin-angiotensin system inhibitors (hazard ratio [95% confidence interval], 5.81 [1.07-31.57] and 4.24 [1.71-10.53], respectively). Regarding pancreatic cancer, patients treated with antihypertensive drugs other than renin-angiotensin system inhibitors had a significantly increased risk of metastasis (hazard ratio [95% confidence interval], 3.31 [1.43-7.69]). Future larger studies are needed to ascertain whether renin-angiotensin system inhibitors can increase the risk of metastasis in skin and renal cancers, focusing on specific tissue types and potential factors associated with renin-angiotensin system inhibitor use.

Analysis of Differences in Preterm Birth Rates According to Household Occupation in Japan From 2007 to 2019.

OBJECTIVES: No studies have examined the association between preterm birth rates and socioeconomic factors in Japan using nationwide statistical data. We analyzed the association between preterm birth rates and household occupation using Vital Statistics data. METHODS: Aggregated Vital Statistics data from Japan from 2007 to 2019 were obtained from the Ministry of Health, Labour and Welfare. From the data, the number of births according to year, age group, gestational period, number of pregnancies, and household occupation were used in this study. Crude preterm birth rates and preterm birth rates adjusted by maternal age according to household occupation were calculated for each year. Poisson regression analysis was conducted to evaluate the association between household occupation and preterm births. RESULTS: Unemployed households had the highest preterm birth rate, and households with an occupation classification of "full-time worker 2" (an employee at a large company, civil servant, or board member) had the lowest preterm birth rate throughout each period. Poisson regression analysis revealed that unemployed households were statistically significantly associated with a high preterm birth risk. In contrast, the preterm birth rate adjusted by maternal age remained stable throughout each period regardless of household occupation, and preterm birth rates were found not to have increased in recent years in Japan. CONCLUSIONS: Unemployed households had higher preterm birth rates than other household occupations. Further studies investigating the characteristics of unemployed households are needed to identify the reasons for this disparity.

A simplified prediction model for end-stage kidney disease in patients with diabetes.

This study aimed to develop a simplified model for predicting end-stage kidney disease (ESKD) in patients with diabetes. The cohort included 2549 individuals who were followed up at Kyushu University Hospital (Japan) between January 1, 2008 and December 31, 2018. The outcome was a composite of ESKD, defined as an eGFR < 15 mL min-1 [1.73 m]-2, dialysis, or renal transplantation. The mean follow-up was 5.6 [Formula: see text] 3.7 years, and ESKD occurred in 176 (6.2%) individuals. Both a machine learning random forest model and a Cox proportional hazard model selected eGFR, proteinuria, hemoglobin A1c, serum albumin levels, and serum bilirubin levels in a descending order as the most important predictors among 20 baseline variables. A model using eGFR, proteinuria and hemoglobin A1c showed a relatively good performance in discrimination (C-statistic: 0.842) and calibration (Nam and D'Agostino [Formula: see text]2 statistic: 22.4). Adding serum albumin and bilirubin levels to the model further improved it, and a model using 5 variables showed the best performance in the predictive ability (C-statistic: 0.895, [Formula: see text]2 statistic: 7.7). The accuracy of this model was validated in an external cohort (n = 5153). This novel simplified prediction model may be clinically useful for predicting ESKD in patients with diabetes.

The association between the socioeconomic deprivation level and ischemic heart disease mortality in Japan: an analysis using municipality-specific data.

OBJECTIVES: Geographical variation in the standardized mortality ratio (SMR) for ischemic heart disease (IHD) among municipalities has not been assessed in Japan. Additionally, associations between area-level socioeconomic deprivation indices and IHD mortality have not been identified in Japan. The present study investigated this association. METHODS: Information on IHD mortality was extracted from Vital Statistics data from 2018 to 2020 for each municipality in Japan. The socioeconomic deprivation level was derived from multiple socioeconomic characteristics. We classified municipalities into quintiles based on the deprivation level and investigated the association between the deprivation level and the SMR of IHD. Additionally, a Bayesian spatial regression model was used to investigate this association, adjusting for other municipal characteristics. RESULTS: Geographical variation in the SMR of IHD was revealed, and municipalities with high SMRs were spatially clustered. There was a weak negative correlation between the socioeconomic deprivation level and the SMRs (correlation coefficient, -0.057 for men and -0.091 for women). In contrast, the regression analysis showed a statistically significant positive association between deprived areas and the IHD mortality rate, and the relative risks for the most deprived municipalities compared with the least deprived municipalities were 1.184 (95% credible interval [CrI], 1.110 to 1.277) and 1.138 (95% CrI, 1.048 to 1.249) for men and women, respectively. CONCLUSIONS: A weak negative correlation between the socioeconomic deprivation level and the SMR was observed in the descriptive analysis, while the regression analysis showed that living in deprived areas was statistically positively associated with the IHD mortality rate.

Prescribing Trends Psychotropic Drugs Against Children and Adolescents and Association with Polypharmacy Reduction Policy for Psychotropic Drugs: Based on Japanese National Database Survey.

In Japan, the polypharmacy reduction policy for psychotropic drugs is intended to reduce the reimbursement of medical costs when "three or more types of psychotropic drugs" are prescribed. However, non-polypharmacy patients who need multiple drugs are also comprehensively evaluated. This study demonstrated that the polypharmacy reduction policy for psychotropic drugs is associated with reductions of the amounts of in-hospital prescriptions for patients using antidepressants, antipsychotics, anxiolytics, and benzodiazepines.

Association of Esophageal Cancer Mortality with Municipal Socioeconomic Deprivation Level in Japan, 2013-2017: An Ecological Study Using Nationwide Data.

This study aimed to show geographical differences in esophageal cancer mortality in Japan and reveal an association of esophageal cancer mortality with municipal socioeconomic deprivation level. Esophageal cancer mortality data in the Vital Statistics from 2013 to 2017 for each municipality and corresponding population data were analyzed. The deprivation level was derived from the municipal socioeconomic variables by principal component analysis. Municipalities were classified into five quintiles based on the deprivation level, and an association between the level and esophageal cancer mortality was evaluated using a Bayesian spatial model. As a result of regression analysis, the relative risk of esophageal cancer mortality tended to become larger as the deprivation level increased irrespective of sex, and the relative risk of esophageal cancer mortality was significantly higher in quintile 5 (most deprived) than quintile 1 (least deprived) among men and women. These results suggest that the deprivation level increases the risk of esophageal cancer mortality in Japan.

Analysis of the association between areal socioeconomic deprivation levels and viral hepatitis B and C infections in Japanese municipalities.

BACKGROUND: We investigated the association between municipal socioeconomic deprivation levels and the positivity of hepatitis B surface antigen (HBsAg) and the prevalence of hepatitis C virus (HCV) among individuals who have never participated in hepatitis screening using Japanese national screening data. METHODS: The hepatitis virus screening data analyzed included the 5-year age group-specific number of participants aged 40 years or older, number of HBsAg-positive persons, and number of HCV carriers for each municipality from 2013 to 2017. Principal component analysis was used to derive a socioeconomic deprivation level using the socioeconomic characteristics of municipalities. Bayesian spatial Poisson regression analysis was conducted to investigate the association between the socioeconomic deprivation level and the results of screening. Data on 1,660 municipalities were used in the analysis. RESULTS: The data of 4,233,819 participants in the HBV screening and 4,216,720 in the HCV screening were used in the analysis. A principal component interpreted as level of rurality (principal component 1) and another principal component interpreted as level of low socioeconomic status among individuals (principal component 2) were extracted as the major principal components. Their principal component scores were used as the deprivation levels of municipalities. Spatial regression analysis showed that the deprivation level derived from the sum of the scores of principal components 1 and 2 was significantly and positively associated with HBsAg positivity and HCV prevalence. In addition, the deprivation level derived only from the score of principal component 2 was also significantly and positively associated with the outcomes. Conversely, the deprivation level derived only from the score of principal component 1 was not associated with the outcomes. Moreover, population density was significantly and positively associated with HBsAg positivity and HCV prevalence. CONCLUSIONS: This study suggested that participation in hepatitis virus screening is important and meaningful, particularly for areas with a higher lower socioeconomic level in Japan.

Differences in Rates of Low Birth Weight among Prefectures in Japan: An Ecological Study Using Government Statistics Data.

The differences in the rates and trends of the overall low birth weight and term low birth weight in recent years are unknown for the Japanese prefectures. In this ecological study, we revealed the rates for each prefecture and investigated the factors affecting the regional differences in these outcomes. Aggregated vital statistics data from 2007 to 2019 were obtained from the Ministry of Health, Labour, and Welfare in Japan. The association between the outcomes and the variables, including the infants' birth characteristics, medical characteristics, and socioeconomic characteristics of the prefectures, were analyzed. An analysis of repeated-measures data was conducted using the data from 2013 and 2018 for each prefecture. The trend for the rates of overall low birth weight and term low birth weight over the years differed among the prefectures. Moreover, the proportions of multiple births and lean (body mass index <18.5 kg/m2) and obese (body mass index ≥25.0 kg/m2) women had a statistically significant positive association with both the overall low birth weight rate and the term low birth weight rate among the prefectures. It was suggested that to resolve the difference in these outcomes among the prefectures, being obese or underweight needs to be addressed in mothers.