Gestational weight gain growth charts adapted to Japanese pregnancies using a Bayesian approach in a longitudinal study: The Japan Environment and Children's Study

Recent Status of Low-Birth-Weight Infants in Japan

Objective In this study, we examined the recent trends in neonatal birth weight in Japan with the precise gestational age distinctions of 39 weeks, which is the period internationally considered to be the most optimal for delivery based on the perinatal outcomes. Materials and methods Firstly, we calculated the frequency of low-birth-weight (LBW) infants beyond 22 weeks of gestation in Japan using the birth notifications from 2000, 2010, and 2020. Secondary, we analyzed the birth weight trends of the first singleton male and female infants born to primiparous women at 39 weeks of gestation. Results The frequency of LBW infants increased significantly in 2010 compared to 2000 (odds ratio 1.13, 95% confidence interval 1.12-1.14, p < 0.01); however, it decreased significantly in 2020 (odds ratio 0.952, 95% confidence interval 0.943-0.961, p < 0.01), although it did not reach the level in 2000 (p < 0.01). The average neonatal birth weight born to primiparous women at 39 weeks of gestation in 2010 was significantly lower than in 2000 (p < 0.01); however, in 2020 it was significantly higher than in 2000 although some differences were observed between the neonatal sexes (p < 0.01). Conclusion The frequency of LBW infants has been declining from 2010 to 2020 in Japan. In addition, the average neonatal birth weight born to primiparous women at 39 weeks of gestation in 2020 was significantly higher than in 2010.

Validity of a self-administered food frequency questionnaire for genomic and omics research among pregnant women: the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study

BACKGROUND

The Tohoku Medical Megabank Project has initiated the Birth and Three-Generation Cohort Study (TMM BirThree Cohort Study) including genomic and omics investigations, and conducted a self-administered food frequency questionnaire with the response option "constitutionally unable to eat or drink it" for individual food items (TMM-FFQ) for pregnant women. This study evaluated the validity of the TMM-FFQ among pregnant women.

METHODS

Participants comprised 122 pregnant women aged ≥20 years residing in Miyagi Prefecture who completed weighed food records (WFRs) for 3 days as reference intake and the TMM-FFQ during mid-pregnancy. Correlations between nutrient or food group intakes based on the WFR and the TMM-FFQ were calculated using Spearman's rank correlation coefficients (CCs), adjusting for energy intake and correcting for random within-individual variation of WFR. Cross-classification was also conducted according to quintiles using the WFR and TMM-FFQ data.

RESULTS

The percentages of participants who chose the "constitutionally unable to eat or drink it" option were >3% for seven food and drink items. CCs were >0.30 for 31 nutrients; the median across energy and 44 nutrients was 0.41. CCs were >0.30 for 14 food groups; the median across 20 food groups was 0.35. The median percentages of cross-classification into exact plus adjacent quintiles and extreme quintiles were 63.1% and 3.3% for energy and nutrients and 61.9% and 4.1% for food groups, respectively.

CONCLUSIONS

The validity of the TMM-FFQ compared with the WFR was reasonable for certain nutrients and food groups among pregnant women in the TMM BirThree Cohort Study.

Impact of changes in recommendation of optimal gestational weight gain in Japan: A retrospective study in a single tertiary center

AIM

In March 2021, the Japanese Ministry of Health, Labour and Welfare revised the optimal gestational weight gain standards. In this study, we examined whether this revision affected gestational weight gain and low birth weight rates.

METHODS

We analyzed the records of singleton pregnant women who underwent checkups from their 1st trimester and delivered at our institute after 37 weeks between 2020 and 2021 (before the revision) and between 2022 and 2023 (after the revision). Pregnancy outcomes were assessed in the following four groups stratified by pre-pregnancy body mass index (BMI): underweight (BMI: <18.5 kg/m2), normal-weight (BMI: 18.5-24.9 kg/m2), overweight (BMI: 25-29.9 kg/m2), and obese (BMI: ≥30 kg/m2). Leaflets on the optimal gestational weight gain standards for each group were distributed to all pregnant women at the first prenatal checkup.

RESULTS

In each group, gestational weight gain did not change before and after the revision, with the corresponding values of 10.8 kg and 11.1 kg in the underweight (p = 0.94), 10.7 kg and 10.4 kg in the normal weight (p = 0.14), 9.7 kg and 9.2 kg in the overweight (p = 0.32), and 7.4 kg and 6.7 kg in the obese (p = 0.44) groups. Furthermore, the prevalence of low birth weight did not decrease in all groups.

CONCLUSIONS

No significant differences in gestational weight gain or low birth weight were observed after the revision of the 2021 gestational weight gain recommendations. Merely distributing leaflets to pregnant women may not be sufficient to improve gestational weight gain or reduce low birth weight rates.

Association between gestational weight gain and behavioral problems of the offspring aged 6-7 years: A population-based study in Japan

OBJECTIVE

To identify the optimal gestational weight gain (GWG) thresholds for behavioral problems and prosocial behavior in 6- to 7-year-old children.

METHODS

A retrospective cohort study was conducted using data from the Adachi Child Health Impact of Living Difficulty study, including all first-graders in public schools in Adachi, Tokyo, in 2017, 2019, and 2021 (n = 11 048, response rate = 80.1%). GWG was based on clinical records in the Mother and Child Health Handbook. Total difficulties and prosocial behavior were assessed using the Strength and Difficulties Questionnaire. Logistic regression models with restricted cubic splines, and quintile categories were employed to examine the association of GWG with the clinical range of total difficulties and prosocial behavior, controlling for covariates.

RESULTS

The association between GWG and total difficulties exhibited a reverse J-shaped pattern, with low GWG, but not high GWG, increasing the risk (odds ratio [OR] 1.20, 95% confidence interval [CI] 1.01-1.42, P = 0.039 for GWG < 7 kg; OR 1.03, 95% CI 0.85-1.24, P = 0.786 for GWG > 14 kg), referencing the median (10 kg). High GWG was associated with a lower risk of problems in prosocial behavior (OR = 0.77, 95% CI 0.62-0.95, P = 0.017 for GWG > 14 kg; OR 1.06, 95% CI 0.88-1.27, P = 0.532 for GWG <7 kg).

CONCLUSION

GWG less than 7 kg may increase the risk of total difficulties, whereas GWG over 14 kg may serve as a protective factor for prosocial behavior in 6- to 7-year-old children.

Associations of gestational weight gain with birth weight outcomes in early pregnancy weight loss women: Findings from the Beijing Birth Cohort Study

OBJECTIVE

To explore the relationship between gestational weight gain (GWG) and birth weight outcomes and establish suggested GWG patterns in early pregnancy weight loss women.

METHODS

This retrospective study was conducted based on the Beijing Birth Cohort Study from 2014 to 2021 and included 20 688 women. Weight change in early pregnancy was calculated using weight measurements within 16 weeks of gestation. Multivariable logistic regression was used to analyze the relationships of different GWG categories, based on the Chinese standard, and birth weight outcomes. The statistical-based approach was used to determine the optimal GWG ranges and weekly weight gain.

RESULTS

Compared to 3313 women who gained appropriate weight in early pregnancy, 2614 women who lost weight in the same period increased the risk of small for gestational age (SGA) (OR = 1.43, 95% CI: 1.14-1.80, P = 0.002). However, the relationship disappeared after adjusting for total GWG. Among the early pregnancy weight loss women, both excessive GWG and inadequate GWG were associated with adverse birth weight outcomes after adjusting for confounders. The suggested GWG range and rate were 11.0 ~ 16.0 kg and 0.46 to 0.67 kg/week from 16 weeks to delivery for women with normal body mass index (BMI) and weight loss in early pregnancy.

CONCLUSION

Weight loss in early pregnancy was not the independent risk factor of birth weight outcomes. GWG may offset the expected effects. To achieve optimal outcomes, women with normal BMI and weight loss in early pregnancy need to have a higher weight gain rate in mid-late pregnancy but similar total GWG ranges with the Chinese standard for general women.

An Application of a Physiologically Based Pharmacokinetic Approach to Predict Ceftazidime Pharmacokinetics in a Pregnant Population

Physiological changes during pregnancy can alter maternal and fetal drug exposure. The objective of this work was to predict maternal and umbilical ceftazidime pharmacokinetics during pregnancy. Ceftazidime transplacental permeability was predicted from its physicochemical properties and incorporated into the model. Predicted concentrations and parameters from the PBPK model were compared to the observed data. PBPK predicted ceftazidime concentrations in non-pregnant and pregnant subjects of different gestational weeks were within 2-fold of the observations, and the observed concentrations fell within the 5th-95th prediction interval from the PBPK simulations. The calculated transplacental clearance (0.00137 L/h/mL of placenta volume) predicted an average umbilical cord-to-maternal plasma ratio of 0.7 after the first dose, increasing to about 1.0 at a steady state, which also agrees well with clinical observations. The developed maternal PBPK model adequately predicted the observed exposure and kinetics of ceftazidime in the pregnant population. Using a verified population-based PBPK model provides valuable insights into the disposition of drug concentrations in special individuals that are otherwise difficult to study and, in addition, offers the possibility of supplementing sparse samples obtained in vulnerable populations with additional knowledge, informing the dosing adjustment and study design, and improving the efficacy and safety of drugs in target populations.

Investigation of optimal weight gain during pregnancy: A retrospective analysis of the Japanese perinatal registry database

AIM

This study aimed to determine the weight gain during pregnancy that minimizes the predicted probability of various perinatal adverse events according to the pre-pregnancy body mass index (BMI) and make recommendations for optimal weight gain in Japan.

METHODS

The Japan Society of Obstetrics and Gynecology perinatal database for 2015-2017 was used. From the 719 723 deliveries included in this database, parturients with underlying diseases or missing data were excluded, and 419 114 deliveries were analyzed. A questionnaire survey was also conducted to weigh each perinatal adverse event. For each of the nine outcomes, a restricted cubic spline model was made to estimate the association between the "expected gestational weight gain at 40 weeks" and the outcome risk.

RESULTS

Since the classes of medical facilities were generally the same, weights were assigned according to the mean of the questionnaires rather than by the class of the facility. For each pre-pregnancy BMI, the weight gains during pregnancy that minimized the predicted probability of various adverse perinatal events were 12-15, 10-13, 7-10, and upper limit of 5 kg for the underweight, normal-weight, obese 1, and obese ≥2 groups, respectively.

CONCLUSIONS

The weight gain during pregnancy that minimizes the predicted probability of various perinatal adverse events according to the pre-pregnancy BMI was established.

The Population-Attributable Fractions of Small-for-Gestational-Age Births: Results from the Japan Birth Cohort Consortium

A fetal growth restriction is related to adverse child outcomes. We investigated risk ratios and population-attributable fractions (PAF) of small-for-gestational-age (SGA) infants in the Japanese population. Among 28,838 infants from five ongoing prospective birth cohort studies under the Japan Birth Cohort Consortium, two-stage individual-participant data meta-analyses were conducted to calculate risk ratios and PAFs for SGA in advanced maternal age, pre-pregnancy underweight, and smoking and alcohol consumption during pregnancy. Risk ratio was calculated using modified Poisson analyses with robust variance and PAF was calculated in each cohort, following common analyses protocols. Then, results from each cohort study were combined by meta-analyses using random-effects models to obtain the overall estimate for the Japanese population. In this meta-analysis, an increased risk (risk ratio, [95% confidence interval of SGA]) was significantly associated with pre-pregnancy underweight (1.72 [1.42-2.09]), gestational weight gain (1.95 [1.61-2.38]), and continued smoking during pregnancy (1.59 [1.01-2.50]). PAF of underweight, inadequate gestational weight gain, and continued smoking during pregnancy was 10.0% [4.6-15.1%], 31.4% [22.1-39.6%], and 3.2% [-4.8-10.5%], respectively. In conclusion, maternal weight status was a major contributor to SGA births in Japan. Improving maternal weight status should be prioritized to prevent fetal growth restriction.

Association between gestational weight gain and chronic disease risks in later life

To assess the association between gestational weight gain (GWG) and the risk of developing chronic diseases in later life, this historical cohort study of 318 non-overweight women was conducted between April 2017 and November 2020 at a hospital in Tokyo. Data about GWG in the last pregnancy and the development of any chronic diseases of the subjects were retrieved from the women's Maternal and Child Health Handbooks and through a questionnaire survey, respectively. The outcomes were chronic diseases, such as diabetes mellitus (DM), hypertension, hyperlipidemia, and being overweight (body mass index [BMI] ≥ 25 kg/m2). Association between GWG and outcomes were assessed using a logistic regression analysis.There were significant positive linear associations between GWG and the risks of developing DM, hypertension, and being overweight (P = 0.013, 0.050, and 0.017, respectively). After adjusting for later-life BMI, a significant association between GWG and DM (P = 0.025) remained, but the association between GWG and hypertension disappeared. GWG was significantly associated with DM, hypertension, and being overweight later in life. Although the association between GWG and DM was partially independent of BMI later in life, the association between GWG and hypertension was influenced by being overweight later in life.

Effective gestational weight gain advice to optimize infant birth weight in Japan based on quantile regression analysis

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.

Current Status of Maternal Gestational Weight Gain and Obstetric Outcomes in Japan

Introduction In 2021, the Japanese Ministry of Health, Labour and Welfare (JMHLW) revised the standard optimal gestational weight gain (GWG) to reduce the incidence of low-birth-weight infants (LBWI) in Japan. In this study, we examined whether maternal GWG increased and LBWI decreased after the revision. Materials and methods We reviewed the obstetric records of singleton pregnant Japanese women who delivered at our institute at ≥37 weeks' gestation in 2020 (before revision) and 2022 (after revision). Results The maternal GWG was significantly increased after the revision of the JMHLW guideline; however, the expected decrease in the incidence of LBWI was not achieved. Conclusion The maternal GWG met the new criteria in the revised guidelines and did not appear to contribute to the reduced incidence of LBWI.

Dietary Intake and Its Association with Birth Outcomes in Women with Nausea and Vomiting during the Second Trimester of Pregnancy: A Prospective Cohort Study in Japan

Nausea and vomiting in pregnancy (NVP) is a common symptom. Although the influence of NVP during the first trimester on dietary intake and birth outcomes has been revealed, no study has focused on NVP during the second trimester. This study aimed to reveal whether NVP severity during the second trimester is associated with dietary intake, gestational weight gain (GWG), birth weight, and delivery week. Participants completed a questionnaire at 18-27 gestational weeks. NVP severity was assessed using the modified Pregnancy-Unique Quantification of Emesis and Nausea scale in the questionnaire. Dietary habits were assessed using a brief-type diet history questionnaire. In total, 825 responses were analyzed: 202 (24.5%), 135 (16.4%), and 8 (1.0%) women reported mild, moderate, and severe NVP, respectively; 480 (58.2%) women did not have NVP during the second trimester. No significant association was observed between energy and nutrient intake and no/mild and moderate/severe NVP. Women with moderate/severe NVP had lower total GWG than those with no/mild NVP (p = 0.007). There was no significant difference in low birth weight and preterm birth rates (p = 0.246 and p = 0.604). This is the first study to investigate whether NVP severity during the second trimester is associated with dietary intake and birth outcomes.

Diet Quality and Its Relationship with Weight Characteristics in Pregnant Japanese Women: A Single-Center Birth Cohort Study

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.

Population attributable fraction of risk factors for low birth weight in the Japan Environment and Children's Study

BACKGROUND

Low birth weight (LBW), which is considered a birth weight of <2500  g, poses significant health problems for children. However, population attributable fraction (PAF) of risk factors for LBW have not been well studied.

OBJECTIVE

We aimed to re-evaluate associations between risk factors for LBW reported in previous studies that used the Japan Environment and Children's Study (JECS) data, and to estimate the magnitude of risk using PAF.

METHODS

Data including 91,559 mother-child dyads were obtained from JECS. Risk factors identified by previous studies that used JECS data were used to calculate odds ratios for LBW using a Bayesian logistic regression model. Based on calculated odds ratios, the PAF was calculated.

RESULTS

Parity, history of adenomyosis, hypertension disorder of pregnancy, maternal age at birth, prepregnancy body mass index, gestational weight gain (GWG), maternal smoking and lead (Pb) exposure were all significantly associated with LBW. The sum of the PAF of all factors was 79.4 %, with the largest PAF among single risk factors being GWG (16.5 %); the environmental portion of the PAF (Pb exposure, 14.6 % + maternal smoking, 12.1 %) surpassed the PAF of GWG.

CONCLUSION

Our findings suggest that the number of births classified as LBW can be reduced by approximately 27% if Pb exposure is reduced to the lowest quartile and maternal smoking is eliminated. Further investigations are needed to identify unknown risk factors for LBW.

Association between Heated Tobacco Product Use during Pregnancy and Fetal Growth in Japan: A Nationwide Web-Based Survey

Combustible cigarette smoking impacts fetal growth during pregnancy. However, the risk associated with heated tobacco products (HTPs) remains unclear. This nationwide cross-sectional study investigated whether HTP use during pregnancy is associated with small for gestational age (SGA) outcomes among 5647 post-delivery women with singleton pregnancies, which were divided into four groups: lifetime never-smokers, former smokers before pregnancy, and current smokers for each of the tobacco products during pregnancy (sole HTP and sole combustion smokers). Information on the prevalence of SGA, defined as birth weight and height below the 10th percentile, was retrieved from the Maternal and Child Health Handbooks of post-delivery women. Using logistic regression, the association between sole HTP smokers during pregnancy and SGA, adjusted for covariates, with lifetime never-smokers as reference, was investigated. The prevalence was: current sole HTP smokers during pregnancy, 1.8% (102/5647); and SGA, 2.9% (164/5647). Sole HTP smokers during pregnancy had a higher prevalence of SGA (5.9% [6/102] vs. 2.7% [111/4144]) with an adjusted odds ratio (OR) of 2.50 (95% confidence interval [CI], 1.03-6.05) than lifetime never-smokers. Among sole combustion smokers, the adjusted OR for SGA was 1.95 (95% CI, 0.81-4.67). In Japan, HTP smoking during pregnancy may be associated with an increased risk for SGA.

Impact of maternal dyslipidemia on infant neurodevelopment: The Japan Environment and Children's Study

BACKGROUND

Various genetic and environmental influences have been studied for developmental disorders; however, the precise cause remains unknown. This study assessed the impact of maternal serum total cholesterol (TC) level in early pregnancy on early childhood neurodevelopment.

METHODS

The fixed data of 31,797 singleton births from a large national birth cohort study that commenced in 2011 were used to identify developmental disorders as estimated by Ages and Stages Questionnaire, third edition (ASQ-3) scores of less than -2 standard deviations at 12 months of age. Multiple logistic regression analysis was employed to search for correlations between possibility of developmental disorders and maternal TC levels in early pregnancy classified into 4 groups based on quartile (Q1-Q4) values.

RESULTS

After controlling for potential confounding factors in 27,836 participants who ultimately underwent multivariate analysis, we observed that elevated TC levels were significantly associated with a higher risk of screen positive status for communication (Q4: adjusted odds ratio [aOR] 1.20, 95% confidence interval [CI] 1.05-1.37) and gross motor (aOR 1.13, 95% CI 1.03-1.25) ASQ-3 domain scores.

CONCLUSION

This large nationwide survey revealed a possible deleterious effect of hypercholesterolemia in early pregnancy on infant neurodevelopment and age-appropriate skill acquisition at 12 months age.