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

Associations of maternal urinary nitrophenol concentrations with adverse birth outcomes and neurodevelopment delay at 4 years of age: The Japan environment and children's study

Maternal urinary nitrophenol concentrations are reportedly associated with preterm birth and foetal/offspring development delay, but the evidence is still inconclusive. We investigated the association between maternal urinary concentrations of 4-nitrophenol (4NP) and 3-methyl-4-nitrophenol (3M4NP) and adverse birth outcomes, as well as offspring neurodevelopment delay, defined using the Ages and Stages Questionnaires at 4 years of age, stratified by offspring sex. A total of 3650 non-hypertensive mothers with singleton births were enrolled from the Japan Environment and Children's Study. High 4NP (≥0.41 μg/L) and 3M4NP (≥0.29 μg/L) were defined as ≥ lowest concentration minimum reporting level. Four groups were created using these dichotomized 4NP and 3M4NP concentrations: 'both low', 'either high/low', and 'both high'. Multivariable logistic regression models were used to estimate the adjusted odds ratios (aOR) and population attributable fraction (PAF). For 4NP and 3M4NP, 68.4% and 19.0% of participants had 'high' urinary concentrations, respectively. Compared to 'both low', the overall analysis showed no significant associations between 'both high' and any of the outcomes. However, the stratified analysis showed that the aOR (95% confidence interval [CI]) and PAF (95% CI) for 'both high' regarding preterm birth (<37 weeks' gestation) were 2.7 (1.3, 5.7) and 16.3% (2.5%, 28.1%), respectively, in male offspring. Among female offspring, the aOR and PAF for the 'both high' regarding small-for-gestational-age (SGA)-defined as weight-for-gestational age <10 percentile based on the Japanese neonatal anthropometric charts-were 1.7 (1.0, 2.8) and 10.6% (-0.2%, 20.2%), respectively. Urinary 4NP and 3M4NP concentrations showed no association with low birth weight (<2500 g) and neurodevelopment delay. In conclusion, offspring sex-specific associations of maternal urinary nitrophenols with preterm birth and SGA were observed. Even slight elevations in their levels may explain a certain proportion of preterm birth and SGA. The exposure source, expressed by urinary nitrophenols, should be identified.

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 blood lipid levels in early pregnancy and urinary organophosphate metabolites in the Japan Environment and Children's Study

BACKGROUND

High low-density lipoprotein cholesterol levels (LDL-C) during pregnancy have been associated with adverse pregnancy and offspring outcomes. While previous studies have suggested a potential link between organophosphate pesticide (OPP) exposure and higher LDL-C in the general population and agricultural workers, the relationship in pregnant women and the effect of body mass index on this relationship remain unclear. We examined the association between the urinary concentrations of OPP metabolites (dialkylphosphates) and blood lipid levels in pregnant women.

METHODS

We used data from the Japan Environment and Children's Study, which included 5,169 pregnant women with urinary dialkylphosphate data. We examined the association between urinary concentrations of six dialkylphosphates (DEP, DETP, DEDTP, DMP, DMTP, DMDTP) and blood lipid levels (LDL-C, total cholesterol, high-density lipoprotein cholesterol, and triglycerides) during the first trimester using multiple linear regression under a Bayesian paradigm. We examined the association between high LDL-C, defined as ≥90th percentile of LDL-C, and urinary dialkylphosphate concentrations, using multiple logistic regression under a Bayesian paradigm. These analyses were repeated in underweight, normal-weight, and overweight participants.

RESULTS

DEP, DMP, and DMTP were detected in >50 % of the participants. Multiple linear regression analyses did not show associations between LDL-C and these dialkylphosphates. Stratified analyses showed a positive association between DEP and LDL-C in overweight women (beta coefficient = 2.13, 95 % credible interval = 0.86-3.38, probability of direction (PD) = 100 %); however, the association was not significant (percentage in region of practical equivalence (% in ROPE) = 84.0). Higher DEP was significantly associated with high LDL-C (odds ratio = 1.32, 95 % credible interval = 1.13-1.55, PD = 100 %, % in ROPE = 0.2).

CONCLUSIONS

Among overweight pregnant women in the first trimester, higher urinary DEP concentrations were associated with high LDL-C. The effects of OPP on blood lipid profiles merit further investigation.

Hokkaido birth cohort study in Japan on the growth trajectory of children born with low birth weight until 7 years of age

BACKGROUND

Low birth weight (LBW) is a significant global health concern with potential health risks and developmental implications for infants. Catch-up growth, an accelerated growth following an inhibition period, may partially compensate for growth deficits in LBW children.

AIMS

This study investigated the prevalence of LBW and catch-up growth in height, weight, and body mass index (BMI) among LBW children in Japan, identified factors associated with LBW, and explored the potential for catch-up growth at different ages up to seven years.

STUDY DESIGN AND SUBJECTS

The Hokkaido birth cohort study included 20,926 pregnant Japanese women recruited during their first trimester from 37 hospitals and clinics. Follow-up assessments were conducted in children up to seven years of age, tracking LBW children's growth and development using the Maternal and Child Health Handbook, and providing valuable insights into catch-up growth patterns.

OUTCOME MEASURES

LBW was defined as a neonatal birth weight of <2500 g. The primary outcomes were catch-up growth in height, weight, and BMI at different ages. Z-scores were calculated to assess growth parameters with catch-up growth, defined as a change in z-score (> 0.67) between two time points.

RESULTS AND CONCLUSIONS

A LBW was prevalent in 7.6 % of the cohort, which was lower than that reported in other Japanese studies. Among LBW children, 19.3 % achieved catch-up growth in height by age seven, and 10.6 % in weight. Catch-up growth in LBW children could partially offset these deficits. Further research will help understand the long-term outcomes and inform interventions for healthy development.

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.

Trajectories of antepartum depressive symptoms and birthweight: a multicenter and prospective cohort study

BACKGROUND

Antepartum depression is a prevalent unhealthy mental health problem worldwide, particularly in low-income countries. It is a major contributor to adverse birth outcomes. Previous studies linking antepartum depression to birthweight have yielded conflicting results, which may be the reason that the depressive symptoms were only measured once during pregnancy. This study aimed to explore the associations between trajectories of antepartum depressive symptoms and birthweight.

METHODS

Depressive symptoms were assessed prospectively at each trimester in 3699 pregnant women from 24 hospitals across 15 provinces in China, using the Edinburgh Postpartum Depression Scale (EPDS). Higher scores of EPDS indicated higher levels of depressive symptoms. Associations between trajectories of depressive symptoms and birthweight were examined using group-based trajectory modeling (GBTM), propensity score-based inverse probability of treatment weighting (IPTW), and logistic regression.

RESULTS

GBTM identified five trajectories. Compared with the low-stable trajectory of depressive symptoms, only high-stable (OR = 1.35, 95% CI: 1.15-2.52) and moderate-rising (OR = 1.18, 95% CI: 1.12-1.85) had an increased risk of low birthweight (LBW) in the adjusted longitudinal analysis of IPTW. There was no significant increase in the risk of LBW in moderate-stable and high-falling trajectories. However, trajectories of depressive symptoms were not associated with the risk of macrosomia.

CONCLUSION

Antepartum depressive symptoms were not constant. Trajectories of depressive symptoms were associated with the risk of LBW. It is important to optimize and implement screening, tracking, and intervention protocols for antepartum depression, especially for high-risk pregnant women, to prevent LBW.

Association of Eicosapentaenoic and Docosahexaenoic Acid Intake with Low Birth Weight in the Second Trimester: The Japan Pregnancy Eating and Activity Cohort Study

This study examined the association of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intake during the second trimester with low birth weight (LBW) in pregnant Japanese women and was conducted in conjunction with the Japan Pregnancy Eating and Activity Cohort (J-PEACH) study. The study included 504 pregnant women from four Japanese sites. During the second trimester (14-27 weeks), the participants filled out a self-administered questionnaire assessing the frequency of DHA and EPA supplement intake in the past month, as well as a brief-type self-administered diet history questionnaire (BDHQ). The analysis involved data from two time points: responses to the BDHQ and infant data at birth. In total, 471 and 33 participants were classified into the normal birth weight and LBW groups, respectively. The participants were divided into high-, medium-, and low-intake groups based on their total dietary and EPA and DHA supplementary intakes. The Cochran-Armitage trend test was used to analyze the data; the prevalence of LBW was higher in the low-intake group (p = 0.04). There was no significant sex-based trend (p = 0.27 and p = 0.35). In Japanese women, low dietary and supplementary EPA and DHA intake until the second trimester were risk factors for LBW.

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.

Effect of Mifepristone vs Placebo for Treatment of Adenomyosis With Pain Symptoms: A Randomized Clinical Trial

Importance

Adenomyosis is a common chronic gynecological disorder, and its treatment is an unmet need. New therapies need to be developed. Mifepristone is being tested for adenomyosis treatment.

Objective

To determine whether mifepristone is effective and safe for adenomyosis treatment.

Design, Setting, and Participants

This multicenter, placebo-controlled, double-blind randomized clinical trial was conducted in 10 hospitals in China. In total, 134 patients with adenomyosis pain symptoms were enrolled. Trial enrollment began in May 2018 and was completed in April 2019, and analyses were conducted from October 2019 to February 2020.

Interventions

Participants were randomized 1:1 to receive mifepristone 10 mg or placebo orally once a day for 12 weeks.

Main Outcomes and Measures

The primary end point was the change in adenomyosis-associated dysmenorrhea intensity, evaluated by the visual analog scale (VAS) after 12 weeks of treatment. Secondary end points included the change in menstrual blood loss, increased level of hemoglobin in patients with anemia, CA125 level, platelet count, and uterine volume after 12 weeks of treatment. Safety was assessed according to adverse events, vital signs, gynecological examinations, and laboratory evaluations.

Results

In total, 134 patients with adenomyosis and dysmenorrhea were randomly assigned, and 126 patients were included in the efficacy analysis, including 61 patients (mean [SD] age, 40.2 [4.6] years) randomized to receive mifepristone and 65 patients (mean [SD] age, 41.7 [5.0] years) randomized to received the placebo. The characteristics of the included patients at baseline were similar between groups. The mean (SD) change in VAS score was -6.63 (1.92) in the mifepristone group and -0.95 (1.75) in the placebo group (P < .001). The total remission rates for dysmenorrhea in the mifepristone group were significantly better than those in the placebo group (effective remission: 56 patients [91.8%] vs 15 patients [23.1%]; complete remission: 54 patients [88.5%] vs 4 patients [6.2%]). All the secondary end points showed significant improvements after mifepristone treatment for menstrual blood loss, hemoglobin (mean [SD] change from baseline: 2.13 [1.38] g/dL vs 0.48 [0.97] g/dL; P < .001), CA125 (mean [SD] change from baseline: -62.23 [76.99] U/mL vs 26.89 [118.70] U/mL; P < .001), platelet count (mean [SD] change from baseline: -28.87 [54.30]×103/µL vs 2.06 [41.78]×103/µL; P < .001), and uterine volume (mean [SD] change from baseline: -29.32 [39.34] cm3 vs 18.39 [66.46] cm3; P < .001). Safety analysis revealed no significant difference between groups, and no serious adverse events were reported.

Conclusions and Relevance

This randomized clinical trial showed that mifepristone could be a new option for treating patients with adenomyosis, based on its efficacy and acceptable tolerability.

Trial Registration

ClinicalTrials.gov Identifier: NCT03520439.

Periconceptional maternal diet quality influences blood heavy metal concentrations and their effect on low birth weight: the Japan Environment and Children's Study

BACKGROUND

Both poor maternal nutrition and toxic heavy metal exposure influence foetal growth and development. However, whether consumption of a variety of healthy foods modifies the association between prenatal heavy metal exposure and foetal growth is unknown.

OBJECTIVE

We examined whether long-term maternal diet quality in periconception modifies the associations between maternal circulating concentrations of heavy metals and foetal growth.

DESIGN

Data of 72,317 Japanese women who delivered singleton infants was extracted from the Japan Environment and Children's Study. Maternal diet over a 1-year before the first trimester of pregnancy was assessed using a validated food frequency questionnaire, and overall diet quality was determined using the balanced diet score based on the Japanese Food Guide Spinning Top. Maternal whole-blood concentrations of mercury (Hg), lead (Pb) and cadmium (Cd) were measured during the second/third trimester of pregnancy. Bayesian inference of multiple linear regression analysis was performed to evaluate the relationships between maternal diet quality and the blood concentrations of heavy metals; Bayesian logistic regression was used to analyse the risk of low birth weight (LBW; <2,500 g).

RESULTS

After controlling for confounders, a high maternal balanced diet score was associated with low concentrations of blood Pb and Cd and high Hg. While all heavy metals assessed were positively associated with LBW risk, a higher maternal balanced diet score was negatively associated with LBW risk. A high-quality maternal diet attenuated the effect of Pb on LBW, an effect that was more marked at high blood Pb concentrations.

CONCLUSION

A high-quality, 'well-balanced' diet prior to conception may reduce exposure to some heavy metals and mitigate the elevated risk of LBW associated with prenatal Pb exposure in Japanese mother-child pairs.