Trends in the prevalence of low birth weight in Okinawa, Japan: a public health perspective

Relationship between prenatal checkup status and low birth weight: a nationwide birth cohort-the Japan Environment and Children's Study

PURPOSE

We investigated the association between prenatal checkup status and low birth weight (LBW). We also sought to identify the background factors of pregnant women that influence their attendance at prenatal checkups and consider measures that might prove useful in reducing the LBW rate.

METHODS

Using data from a large nationwide birth cohort study, the Japan Environment and Children's Study (JECS), the sample comprised 91,916 unique mother-infant pairs with singleton live births. The outcome variable was cases of LBW, and the exposure variable was prenatal checkup status (number of visits missed). Adjusted odds ratios (AORs) with 95% confidence intervals (CIs) were calculated by logistic regression analysis.

RESULTS

AORs (95% CIs) for cases of LBW were 1.57 (1.46-1.69) for 1 missed checkup, 2.40 (1.97-2.94) for 2 missed checkups, and 2.38 (1.46-3.88) for ≥3 missed checkups. A linear trend was also observed (P < .0001). Further analysis revealed that the main risk factors for missed checkups were divorced or widowed marital status, followed by negative attitude toward pregnancy, and single marital status, whereas protective factors were being employed and better mental health in mid-late pregnancy.

CONCLUSIONS

Our results suggest the importance of implementing various measures to promote regular attendance at prenatal checkups.

Detecting geographical clusters of low birth weight and/or preterm birth in Japan

In Japan, mean birth weight has significantly decreased from 3152 g in 1979 to 3018 g in 2010 and the prevalence of preterm birth (PTB) has risen to 5.7% in the last thirty years. However, the presence and magnitude of geographical differences in low birthweight (LBW) and/or PTB in Japan is not well understood. We implemented spatial analysis to identify localized clusters and hot spots of LBW and/or PTB during 2012-2016. The Japan national birth database was used in this study. A total of 5,041,685 (male: 2,587,415, female: 2,454,270) births were used for spatial analysis using empirical Bayes estimates of the incidence rate of LBW and/or PTB and spatial scan tests to detect hot-spot areas with p values calculated from Monte Carlo iterations. The most and second likely clusters were located in two areas: (1) the small islands in south-west Japan (Amami and Okinawa, Relative risk = 1.09-1.67 with p < 0.001) and (2) the cities on the base of Mt. Fuji, stretching over three neighboring prefectures of Yamanashi, Shizuoka and Kanagawa (Relative risk = 1.10-1.55 with p < 0.001), respectively. We need to optimize the medical resource allocations based on the evidence in geographical clustering of LBW and/or PTB at specific locations in Japan.

The role of CD36-Fabp4-PPARγ in skeletal muscle involves insulin resistance in intrauterine growth retardation mice with catch-up growth

BACKGROUND

Studies have shown that the high incidence of type 2 diabetes in China is associated with low birth weight and excessive nutrition in adulthood, which occurred during the famine years of the 1950s and 1960s, though the specific molecular mechanisms are unclear. In this study, we proposed a severe maternal caloric restriction during late pregnancy, followed by a post weaning high-fat diet in mice. After weaning, normal and high-fat diets were provided to mice to simulate the dietary pattern of modern society.

METHODS

The pregnant mice were divided into two groups: normal birth weight (NBW) group and low birth weight (LBW) group. After 3 weeks for weaning, the male offspring mice in the NBW and LBW groups were then randomly divided into four subgroups: NC, NH, LC and LC groups. The offspring mice in the NC, NH, LC and LC groups were respectively fed with normal diet, normal diet, high-fat diet and high-fat diet for 18 weeks. After 18 weeks of dietary intervention, detailed analyses of mRNA and protein expression patterns, signaling pathway activities, and promoter methylation states were conducted for all relevant genes.

RESULTS

After dietary intervention for 18 weeks, the expressions of CD36, Fabp4, PPARγ, FAS, and ACC1 in the skeletal muscle tissue of the LH group were significantly increased compared with the LC and NH groups (P < 0.05). The level of p-AMPK/AMPK in the skeletal muscle tissue of the LH group was significantly decreased compared with the LC and NH groups (P < 0.05). CPT1 and PGC-1α protein expressions were up-regulated in the LH group (P < 0.05) compared to the LC group. Additionally, the DNA methylation levels of the PGC-1α and GLUT4 gene promoters in the skeletal muscle of the LH groups were higher than those of the LC and NH groups (P < 0.05). However, PPARγ DNA methylation level in the LH group was lower than those of the LC and NH groups (P < 0.05).

CONCLUSIONS

LBW combined with high-fat diets may increase insulin resistance and diabetes through regulating the CD36-related Fabp4-PPARγ and AMPK/ACC signaling pathways.

Trends in the prevalence of cerebral palsy in children born between 1988 and 2007 in Okinawa, Japan

AIM

This study aimed to describe trends in CP prevalence among children born between 1988 and 2007 in Okinawa, Japan.

METHOD

This study was conducted during two time periods, Period I (from 1988 to 1997) and Period II (from 1998 to 2007), using data from the local CP registration system. We assessed cerebral palsy gestational age and birth weight specific trends in prevalence and analyzed these with Poisson regression analysis.

RESULTS

Overall crude CP prevalence was 1.88 per 1000 live births. Approximately 70% of children with CP were born preterm or with low birth weight (LBW). Overall CP prevalence increased in Period I and decreased significantly in Period II (P<0.05). Additionally, CP prevalence among children born with a birth weight between 1000 and 1999g increased in Period I and decreased significantly in Period II (P<0.05). A significant decrease was found among the children born between 1995 and 2007 with a gestational age between 28 and 31weeks (P<0.01).

CONCLUSIONS

There was a decrease in CP prevalence from 1998 to 2007, especially among LBW children and preterm infants. The high CP proportions among LBW and preterm infants are unique features of the population of Okinawa, Japan.

Effectiveness of Home Visits in Pregnancy as a Public Health Measure to Improve Birth Outcomes

BACKGROUND

Birth outcomes, such as preterm birth, low birth weight (LBW), and small for gestational age (SGA), are crucial indicators of child development and health.

PURPOSE

To evaluate whether home visits from public health nurses for high-risk pregnant women prevent adverse birth outcomes.

METHODS

In this quasi-experimental cohort study in Kyoto city, Japan, high-risk pregnant women were defined as teenage girls (range 14-19 years old), women with a twin pregnancy, women who registered their pregnancy late, had a physical or mental illness, were of single marital status, non-Japanese women who were not fluent in Japanese, or elderly primiparas. We collected data from all high-risk pregnant women at pregnancy registration interviews held at a public health centers between 1 July 2011 and 30 June 2012, as well as birth outcomes when delivered from the Maternal and Child Health Handbook (N = 964), which is a record of prenatal check-ups, delivery, child development and vaccinations. Of these women, 622 women were selected based on the home-visit program propensity score-matched sample (pair of N = 311) and included in the analysis. Data were analyzed between January and June 2014.

RESULTS

In the propensity score-matched sample, women who received the home-visit program had lower odds of preterm birth (odds ratio [OR], 0.62; 95% confidence interval [CI], 0.39 to 0.98) and showed a 0.55-week difference in gestational age (95% CI: 0.18 to 0.92) compared to the matched controlled sample. Although the program did not prevent LBW and SGA, children born to mothers who received the program showed an increase in birth weight by 107.8 g (95% CI: 27.0 to 188.5).

CONCLUSION

Home visits by public health nurses for high-risk pregnant women in Japan might be effective in preventing preterm birth, but not SGA.

Updated Japanese growth references for infants and preschool children, based on historical, ethnic and environmental characteristics

AIM

To provide updated growth references for Japanese children from birth to 6 years of age, for use in both growth monitoring and child care.

METHODS

We analysed data from two national representative surveys that provided cross-sectional data on 3000 areas in the 2005 national census and longitudinal data from 136 hospitals. Growth references for length/height, weight, head circumference and chest circumference were constructed using the lambda-mu-sigma (LMS) method, with estimates of the L, M and S parameters. These updated values were then compared with growth references published by the World Health Organization.

RESULTS

The 3rd, 50th and 97th smoothed percentile values of length/height, weight, head circumference and chest circumference for boys and girls from birth to 6 years are presented. The comparisons show some large differences in median measurements between the charts.

CONCLUSION

Our growth references are based on a current, nationally representative sample of Japanese children. The results provide deep insight into child growth from a historical, ethnic and environmental point of view.

Active and passive maternal smoking during pregnancy and birth outcomes: the Kyushu Okinawa maternal and child health study

BACKGROUND

In Western countries, active maternal smoking during pregnancy is recognized as the most important preventable risk factor for adverse birth outcomes. However, the effect of passive maternal smoking is less clear and has not been extensively studied. In Japan, there has been only one epidemiological study which examined the effects of active smoking during early pregnancy on birth outcomes although the effects of passive smoking were not assessed.

METHODS

Study subjects were 1565 mothers with singleton pregnancies and the babies born from these pregnancies. Data on active maternal smoking status in the first, second, and third trimesters and maternal environmental tobacco smoke (ETS) exposure at home and work were collected with self-administered questionnaires.

RESULTS

Compared with children born to mothers who had never smoked during pregnancy, children born to mothers who had smoked throughout their pregnancy had a significantly increased risk of small-for-gestational-age (SGA) (adjusted odd ratio [OR] = 2.87; 95% confidence interval: 1.11 - 6.56). However, active maternal smoking only in the first trimester and active maternal smoking in the second and/or third trimesters but not throughout pregnancy were not significantly associated with SGA. With regard to the risk of preterm birth, the adjusted ORs for the above-mentioned three categories were not significant; however, the positive linear trend was significant (P for trend = 0.048). No significant association was found between active maternal smoking during pregnancy and the risk of low birth weight. There was a significant inverse relationship between active maternal smoking during pregnancy and birth weight; newborns of mothers who had smoked throughout pregnancy had an adjusted mean birth weight reduction of 169.6 g. When classifying babies by gender, a significant positive association between active maternal smoking throughout pregnancy and the risk of SGA was found only in male newborns, however, the interaction was not significant. Maternal ETS exposure at home or work was not significantly associated with any birth outcomes.

CONCLUSIONS

This is the first study in Japan to show that active maternal smoking throughout pregnancy, but not during the first trimester, is significantly associated with an increased risk of SGA and a decrease in birth weight. Thus, women who smoke should quit smoking as soon as possible after conception.

Long-term survival of children with cerebral palsy in Okinawa, Japan

AIM

The aim of this study was to describe the survival prognosis of children with cerebral palsy (CP) in Okinawa, Japan.

METHOD

A cohort study was conducted on all children with CP born between 1988 and 2005 in Okinawa, Japan. Survival proportions were determined with a life table and Kaplan-Meier survival curves were plotted. The effect of each predictor variable was estimated using Cox regression analysis.

RESULTS

This study included 580 children with CP (332 males, 248 females). In the cohort, 119 (20.5%) children were classified in Gross Motor Function Classification System (GMFCS) level I, 65 (11.2%) were classified in level II, 40 (6.9%) in level III, 189 (32.6%) in level IV, 166 (28.6%) in level V and GMFCS level was unknown for one. Of the 34 children who died, 29 were classified in GMFCS level V and GMFCS level was unknown for one. Mean age at start of follow-up was 24.5 months (SD 2.6 mo); mean length of follow-up was 8 years 8 months (standard error of the mean 0.214 y). The 5 year- and 18-year survival percentages of the entire cohort were 98% and 89% respectively. In children with CP, significantly lower survival rates were associated with multiple factors, including a birthweight of at least 2500 g (p=0.009), a gestational age of at least 37 weeks (p=0.004), and the most severe gross motor limitation, GMFCS level V (p<0.001). However, multivariate analysis showed GMFCS level V was the only significant predictor variable (p<0.001) for survival of CP.

INTERPRETATION

This study is the first to describe survival of children with CP in Japan. Our results are similar to those previously reported in other countries. These results are important in planning adequate provision of social and medical services for individuals with CP.

Population-based study on association between birth weight and risk of asthma: a propensity score approach

BACKGROUND

Previous studies that assessed the role of birth weight in the risk of asthma have been limited because of selection bias and covariate imbalance.

OBJECTIVE

To assess the association between birth weight and risk of asthma by applying a propensity score approach.

METHODS

The study was designed as a retrospective cohort study based on a birth cohort of children born between January 1, 1976, and December 31, 1979, in Rochester, Minnesota. The propensity scores for birth weight were formulated using 16 covariates. We matched the propensity scores for children having low birth weight (<2,500 g) within a caliper of 0.2 SD of logit function of propensity scores. We calculated the cumulative incidence of asthma between low and normal birth weight groups using the Kaplan-Meier curve.

RESULTS

There were 3933 eligible children born between January 1, 1976, and December 31, 1979. Before matching, 13 of the 193 children (6.7%) born weighing 2,500 g developed asthma, whereas 201 of the 3,740 children (5.4%) born weighing 2,500 g and above developed asthma (P=.42). There were significant covariate imbalances between comparison groups. However, after propensity score matching, covariate imbalance was significantly reduced, and children born weighing less than 2,500 g had a similar risk to matched children born with normal birth weight (8.3% vs 7.3%, P=.75).

CONCLUSION

Birth weight is not associated with risk of asthma during the first 6 years of life. The propensity score may be a useful method for observational studies concerning asthma epidemiology.

Progress in Infant Health in Okinawa, Japan

The infant mortality rate (IMR) and neonatal mortality rate (NMR) defined as the number of infant and newborn deaths per 1000 live births, respectively, are widely accepted as population indicators of the level of perinatal and postnatal health. Since the end of World War II, Japan has made substantial progress in reducing its IMR and NMR. This resulted from improving living standards and the provision of universal maternal and child health care (MCH) services. Okinawa, the island prefecture that is the furthest from mainland Japan, had the third highest IMR and the highest low-birth-weight rate (LBW) among all prefectures when its statistics were integrated into Japan in 1973. Even though the LBW rate in Okinawa has remained higher than the all-Japan average, Okinawa has shown a considerable improvement in IMR and NMR. The aim is to review the trends in IMR, NMR, and LBW in Japan and Okinawa and to discuss sociodemographic trends, economics, and the provision of health care services. The IMR and NMR in Okinawa decreased during that time from 14.8 to 2.4 and from 7.5 to 0.8, respectively. The LBW rate decreased until the mid-1980s, but since then it has increased to 11.5 (Okinawa) and 9.6 (Japan) in 2009. Okinawa’s public health and primary health care model for infants has been very successful and may be applicable to child health in island nations of the Asia-Pacific region.

Neonatal mortality due to preterm birth at 28-36 weeks' gestation in China, 2003-2008

Almost all (99%) neonatal deaths occur in developing countries, where the progress in reducing neonatal mortality rates (NMR) has been small; the Millennium Development Goal for child survival cannot be met if this situation continues. China is among the 10 countries that have the largest numbers of neonatal deaths. In order to provide effective interventions to reduce the national NMR for government policy makers, we analyse the trends, causes and characteristics of the neonatal deaths of preterm babies in different regions of China during the period 2003-2008. The data for this retrospective study were retrieved from the population-based Maternal and Child Health Surveillance System of China. The Cochran-Armitage trend test was used to analyse the trend of NMRs due to immaturity. The national NMR due to immaturity has decreased by 38.7% in 6 years. However, the proportion of preterm births among the causes of neonatal death has increased significantly from 33.6% in 2003 to 40.9% in 2008. The relative risk of neonatal death among preterm babies has shown significant regional disparity. In 2008, the adjusted relative risk was 1.30 [95% confidence interval (CI) 0.95, 1.78] in the inland regions and 2.37 [95% CI 1.56, 3.60] in the remote regions, both compared with the coastal regions. The proportion of neonatal deaths with a gestational age <32 weeks or a birthweight <1500 g was highest among the coastal regions. Most neonatal deaths of preterm babies in remote areas were born at home and were not treated before death. Our study suggests that preterm birth is the leading cause of neonatal death in China and neonatal mortality due to immaturity displayed regional differences. The Chinese government should implement major effective strategies for reducing the mortality of preterm infants to further decrease the total NMR. Priority interventions should be region-specific, depending on the availability of economic and health care resources.

Comments on dietary restriction, Okinawa diet and longevity

Longevity in Okinawa is considered to be a result of traditional low calorie diet. Le Bourg suggests that Okinawa is an example of severe malnutrition, which is harmful for later generations. We believe that current loss of longevity advantage in Okinawa is a result of diet westernization and that the dietary restriction is a valid way of life extension in humans.

Community-based screening for infantile anemia in an okinawan village, Japan

Infancy is a vulnerable age group for anemia throughout the world. However, community-based screening for infantile anemia is seldom reported. This study determined the prevalence of anemia among infants in an Okinawan village from 2003 to 2008, in relation to secondary prevention of the condition. The prevalence among infants aged 3-5, 6-12 and 16-23 months was 12.3%, 15.8%, and 4.2%, respectively, based on cross-sectional surveys (n = 3070), and was 11.0%, 17.2%, and 3.9% according to another retrospective cohort study (n = 511). The relatively low prevalence of anemia at early childhood suggested that previous detection and treatment through early and late infantile screening had been successful.

Island health: hope and challenges for public health

The Asia-Pacific region is a region of small islands, perhaps 100 000 of them. The health, communication, and development problems of islands present difficult challenges for the delivery of health care. The discussions at the Okinawa Symposium centred on how health can be provided to all in the region, not only those in metropolitan areas, but also the poor in rural areas and those on living on far-flung island archipelagos. It is important to apply principles of "public health" and "primary health care" so that all island residents may have a reasonable expectation of health care. Schools of public health have a special responsibility to educate those who are responsible for the delivery and management of health care in these remote locations. The development of telehealth systems will be important to support health workers in remote locations and to deliver continuing education programs.

Impact of change in maternal age composition on the incidence of Caesarean section and low birth weight: analysis of delivery records at a tertiary hospital in Tanzania, 1999-2005

BACKGROUND

Previous studies on change in maternal age composition in Tanzania do not indicate its impact on adverse pregnancy outcomes. We sought to establish temporal changes in maternal age composition and their impact on annual Caesarean section (CS) and low birth weight deliveries (LBWT) at Muhimbili National Hospital in Tanzania.

METHODS

We conducted data analysis of 91,699 singleton deliveries that took place in the hospital between 1999 and 2005. The data were extracted from the obstetric data base. Annual proportions of individual age groups were calculated and their trends over the years studied. Multiple logistic analyses were conducted to ascertain trends in the risks of CS and LBWT. The impact of age composition changes on CS and LBWT was estimated by calculating annual numbers of these outcomes with and without the major changes in age composition, all others remaining equal. In all statistics, a p value < 0.05 was considered significant.

RESULTS

The proportion of teenage mothers (12-19 years) progressively decreased over time while that of 30-34 years age group increased. From 1999, the risk of Caesarean delivery increased steadily to a maximum in 2005 [adjusted OR = 1.7; 95%CI (1.6-1.8)] whereas that of LBWT declined to a minimum in 2005 (adjusted OR = 0.76; 95% CI (0.71-0.82). The current major changes in age trend were responsible for shifts in the number of CS of up to206 cases per year. Likewise, the shift in LBWT was up to 158 cases per year, but the 30-34 years age group had no impact on this.

CONCLUSION

The population of mothers giving birth at MNH is progressively becoming older with substantial impact on the incidence of CS and LBWT. Further research is needed to estimate the health cost implications of this change.