Pregnant Japanese Women Research Articles

Association Between Periconceptional Diet Quality and Hypertensive Disorders of Pregnancy: The Japan Environment and Children's Study.

Little is known about the relationship of healthy diets, which are widely recommended to prevent diseases in general populations, with the risk of hypertensive disorders of pregnancy (HDP), particular among non-Western populations with different dietary habits. We aimed to investigate the association between periconceptional diet quality and the risk of HDP among pregnant Japanese women. Dietary intake over 1 year before the first trimester of pregnancy was assessed using a validated, self-administered food frequency questionnaire among 81 113 pregnant Japanese women who participated in a prospective cohort of the Japan Environment and Children's Study. Overall diet quality was assessed by the Balanced Diet Score (BDS) based on adherence to the country-specific dietary guidelines and the Dietary Approaches to Stop Hypertension (DASH) score. Cases of HDP were identified by medical record transcription. The association between diet quality and HDP risk was examined using Bayesian logistic regression models with monotonic effects. We identified 2383 (2.9%) cases of HDP. A higher BDS was associated with a lower risk of HDP. When comparing the highest with the lowest quintile of the BDS, the adjusted odds ratio (aOR) of HDP was 0.83 (95% credible interval [CrI], 0.73-0.94). The DASH score and HDP risk were inversely associated in a monotonic dose-response manner (aOR per 1-quintile increase in the DASH score, 0.92 [95% CrI, 0.89-0.95]). A high-quality diet, which is recommended for disease prevention in general populations, before conception may also reduce the risk of HDP among pregnant Japanese women.

Association of maternal blood and umbilical cord blood plasma fatty acid levels with the body size at birth of Japanese infants

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), mainly obtained from fish, have been implicated in fetal development. Because few studies have examined maternal and umbilical cord blood fatty acid levels and infant body size in Japan with a fish-eating culture, we examined differences in plasma fatty acid levels in pregnant women and infant size at birth. This study is a large birth cohort study of 1476 pairs of Japanese pregnant women and their infants. Maternal blood DHA levels and infant birth weight showed a positive relationship. However, analysis adjusted for gestational age did not reveal correlations. Negative relationships were found between cord blood DHA levels and infant body size, and between the difference in mother-to-child DHA levels and infant body size. Thus, the smaller the birth size, the higher the differences in umbilical cord blood DHA levels and mother-to-child DHA levels when considering gestational age.

Intraclass correlation coefficients of urinary biomarkers of neonicotinoid insecticides in Japanese pregnant women

Intraclass correlation coefficients of urinary biomarkers of neonicotinoid insecticides in Japanese pregnant women

Longitudinal analysis of body dissatisfaction: the desire to be thinner among women in Japan during low-risk pregnancies.

Body dissatisfaction during pregnancy can significantly impact maternal and child health. Therefore, this longitudinal study investigated changes in body dissatisfaction using two figure rating scales developed from photographic digital data of Japanese pregnant women during the sixth and tenth months of pregnancy. Study participants were recruited at their sixth month prenatal visit at a primary maternity clinic in Japan from October 2014 to March 2015. Body dissatisfaction was estimated based on the perceived and ideal body sizes of 135 pregnant women, expressed as body mass index. Data were collected using self-administered questionnaires. The study found that body dissatisfaction in the tenth month was significantly higher than that in the sixth month. Among the participants, 75 (55.6%) and 79 (58.5%) experienced body dissatisfaction, desiring to be thinner (where perceived body size exceeded ideal body size) during the sixth and tenth months of pregnancy, respectively. Pregnant women who had body dissatisfaction and a desire to be thinner in the sixth month tended to experience an increase in body dissatisfaction by the tenth month compared to those without body dissatisfaction in the sixth month. During the sixth and tenth months, women with body dissatisfaction showed significantly larger perceived body sizes than those without body dissatisfaction. These results indicated that the use of a figure rating scale at the sixth month of pregnancy may help identify women with body dissatisfaction; moreover, perceived body size might be a key factor in preventing an increase in body dissatisfaction from the second to third trimesters.

Maternal excessive weight gain as a potential risk factor for prolonged labor in Japanese pregnant women: The Japan Environment and Children's Study.

This study aimed to determine whether excessive maternal weight gain during pregnancy was associated with a higher risk of prolonged labor. We analyzed the data regarding maternal weight gain during pregnancy for the participants of Japan Environment and Children's Study (JECS), which is an ongoing nationwide prospective birth cohort study in Japan. After excluding participants with multiple pregnancies, with deliveries before 37 or beyond 42 weeks of gestation, or who had undergone cesarean section, 71,154 (nulliparous, n = 28,442) Japanese women were included. Prolonged labor was defined by a cutoff ranking at the 95th percentile and consequently defined as labor duration exceeding 12.7 h in multiparous women and exceeding 23.2 h in nulliparous women. These classifications were made according to labor curves established by the Japanese Society of Obstetrics and Gynecology Perinatal Committee developed in June 2021. Considering that no studies have conducted an investigation based on this new guideline, we analyzed the association between excessive maternal weight gain during pregnancy and prolonged labor by parity. The overall incidence of prolonged labor was 10.2% (2,907/28,442) in nulliparous women and 6.1% (2,597/42,712) in multiparous women. Multivariable analysis indicated that excessive maternal weight gain was significantly associated with prolonged labor in nulliparous (adjusted odds ratio, 1.21; 95% confidence interval, 1.10-1.32) and multiparous women (adjusted odds ratio, 1.15; 95% confidence interval, 1.05-1.27). Kaplan-Meier survival analysis showed that as labor progressed, the percentage of women who had not yet delivered was higher among those with excessive maternal weight gain than among those with normal maternal weight gain in both the nulliparous (median labor duration 12.9 h vs 12.2 h, p<0.001) and multiparous (median labor duration 6.2 h vs 5.8 h, p<0.001) groups. Excessive maternal weight gain was significantly associated with prolonged labor in Japanese women.

Maternal pre-pregnancy body mass index and related factors: A cross-sectional analysis from the Japan Environment and Children's Study.

Socioeconomic status and smoking are reportedly associated with underweight and obesity; however, their associations among pregnant women are unknown. This study aimed to investigate whether socioeconomic factors, namely educational attainment, household income, marital status, and employment status, were associated with pre-pregnancy body mass index (BMI) categories, including severe-moderate underweight (BMI ≤ 16.9 kg/m2), mild underweight (BMI, 17.0-18.4 kg/m2), overweight (BMI, 25.0-29.9 kg/m2), and obese (BMI ≥ 30.0 kg/m2) among Japanese pregnant women using data from the Japan Environment and Children's Study (JECS). In total, pregnant women were included 96,751. Age- and parity-adjusted multivariable multinomial logistic regression analyses assessed socioeconomic factors and smoking associations with falling within abnormal BMI categories (normal BMI as the reference group). Lower education and lower household were associated with overweight and obesity, and, especially, lowest education and household income had relatively higher point estimate relative ratios (RRs) of 3.97 and 2.84, respectively. Regarding the risks for underweight, however, only junior high school education had a significantly higher RR for severely to moderately underweight. Regarding occupational status, homemakers or the unemployed had a higher RR for severe-moderate underweight, overweight, and obesity. Unmarried, divorced, or bereaved women had significantly higher RRs for mildly underweight status. Quitting smoking early in pregnancy/still smoking had higher RRs for all four not having normal BMI outcomes; however, quitting smoking before pregnancy had a higher RR only for obese individuals. Lower educational attainment and smoking are essential intervention targets for obesity and severe-moderate underweight prevention in younger women. Lower household income is also a necessary target for obesity.

Reliability and validity of the Japanese version of the Pregnancy and Weight Gain Attitude Scale.

This study aimed to develop the Japanese version of the Pregnancy and Weight Gain Attitude Scale (J-PWGAS) as a measurement of body image regarding body weight and shape during pregnancy. This cross-sectional study was conducted at a perinatal medical center in Osaka, Japan, between March and November 2020. We recruited pregnant women in their second or third trimester, who were 20 years old or older and without pregnancy complications. This study evaluated the criterion validity, construct validity, internal consistency, and test-retest reliability. Of the participants, 218 and 102 women participated in the validation and test-retest reliability studies, respectively. An exploratory factor analysis revealed a 17-item, five-factor structure. The J-PWGAS indicated acceptable criterion validity, internal consistency, and test-retest reliability. The J-PWGAS can measure attitudes toward gestational weight gain in Japanese pregnant women and would be useful in examining the association of body image with weight gain and psychological status during pregnancy.

A sensor-augmented pump with a predictive low-glucose suspend system could lead to an optimal time in target range during pregnancy in Japanese women with type 1 diabetes.

It is challenging for pregnant women with type 1 diabetes to maintain optimum glucose level to attain good neonatal outcomes. This study evaluated the efficacy of sensor-augmented insulin pump (SAP) with a predictive low-glucose suspend (PLGS) system in pregnant Japanese women with type 1 diabetes. SAP with PLGS was used in 11 of the 22 women with type 1 diabetes who delivered between 2011 and 2021 at the two medical institutions in Japan. Glucose management, insulin delivery suspension time (IST) and neonatal outcomes were retrospectively studied. In SAP with PLGS cases (n = 11), average glycated hemoglobin levels were < 6.5% throughout the pregnancy, and the time in range (TIR, 63-140mg/dl) was > 70% in the second and third trimesters. PLGS was safely used without inducing ketoacidosis. Positive correlation was observed between IST and TIR (r = 0.62, p < 0.01). Negative correlation was observed between IST and time below range (TBR) (r = - 0.40, p = 0.02), and IST and time above range (TAR) (r = - 0.45, p = 0.01). Total daily insulin dose was adequately increased without increasing hypoglycemia. There was only one heavy-for-date HFD) infant among the 11 newborns in SAP with PLGS cases. In cases without SAP (n = 11), target glycemic levels were difficult to achieve and there were 5 HFD infants among the 11 newborns. SAP with PLGS was safely and effectively used in pregnant women with type 1 diabetes to achieve target glucose levels without increasing the risk of hypoglycemia, which may have led to good neonatal outcomes. The online version contains supplementary material available at 10.1007/s13340-024-00716-7.

Maternal birth weight as an indicator of early and late gestational diabetes mellitus: The Japan Environment and Children's Study.

This study aimed to investigate the association of maternal birth weight (MBW) with early and late gestational diabetes mellitus (GDM). A total of 69318 pregnant Japanese women were included in this birth cohort study. The associations between maternal birth weight and early gestational diabetes mellitus (diagnosed at <24 gestational weeks) and late GDM (diagnosed at ≥24 gestational weeks) were investigated using a multinomial logistic regression model, with an maternal birth weight of 3000-3499 g as the reference category. Lower maternal birth weight was associated with higher odds of developing early and late gestational diabetes mellitus (P < 0.0001 and P < 0.0001, respectively). The adjusted odds ratios (aORs) for early gestational diabetes mellitus in participants with a MBW of <2500 g and 2500-2999 g were 1.345 (95% confidence interval [CI]: 0.912-1.984) and 1.338 (95% CI: 1.098-1.629), respectively. The aORs for late gestational diabetes mellitus in participants with a MBW of <2500 g and 2500-2999 g were, 1.657 (95% CI: 1.298-2.115) and 1.218 (95% CI: 1.058-1.402), respectively. Regardless of the gestational age when gestational diabetes mellitus was diagnosed, a lower maternal birth weight was associated with an increased risk of gestational diabetes mellitus. Furthermore, the association of a MBW <2500 g with late gestational diabetes mellitus tended to be stronger than that with early gestational diabetes mellitus.

Clinical relevance of reversible cerebral vasoconstriction syndrome in pregnant women with posterior reversible encephalopathy syndrome: review of case reports in Japan.

We systematically reviewed case reports of posterior reversible encephalopathy syndrome (PRES), and investigated the characteristics of PRES in pregnant Japanese women and the clinical relevance of reversible cerebral vasoconstriction syndrome (RCVS) in pregnant women with PRES. Articles were collected using the PubMed/Medline and Ichushi-Web databases. This review was ultimately conducted on 121 articles (162 patients). The clinical characteristics of PRES, individual sites of PRES lesions, edema types, and clinical characteristics of RCVS in PRES cases were examined. The most common individual site of PRES lesion was the occipital lobe (83.3%), followed by the basal ganglia, parietal lobe, frontal lobe, brain stem, cerebellum, temporal lobe, thalamus, and splenium corpus callosum (47.5, 42.6, 24.7, 16.1, 9.3, 5.6, 4.3, and 0.0%, respectively). Edema types in 79 cases with PRES were mainly the vasogenic edema type (91.1%), with very few cases of the cytotoxic edema type (3.8%) and mixed type (5.1%). Among 25 PRES cases with RCVS, RCVS was not strongly suspected in 17 (68.0%) before magnetic resonance angiography. RCVS was observed at the same time as PRES in 13 cases (approximately 50%), and between days 1 and 14 after the onset of PRES in the other 12. These results suggest that the basal ganglia is a frequent site of PRES lesions in pregnant women. RCVS may occur at or after the onset of PRES, even if there are no symptoms to suggest RCVS.

Association between body shape satisfaction and nutrient intake among pregnant Japanese women

Association between body shape satisfaction and nutrient intake among pregnant Japanese women

Associations of fasting plasma glucose and glycosylated hemoglobin levels at less than 24 weeks of gestation with hypertensive disorders of pregnancy: the BOSHI study.

This study aimed to evaluate the associations of fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c) levels at <24 weeks of gestation with hypertensive disorders of pregnancy (HDP) and compare the strengths of the associations of HDP with FPG and HbA1c levels. Totally, 1,178 participants were included in this prospective cohort study. HDP, FPG, HbA1c, and potential confounding factors were included in multiple logistic regression models. The number of HDP cases was 136 (11.5%). When FPG and HbA1c were included in the model separately, quartile 4 (Q4) of FPG (87-125 mg/dL) and HbA1c (5.2-6.3% [33-45 mmol/mol]) levels had higher odds of HDP than quartile 1. The odds ratios (ORs) were 1.334 (95% confidence interval [CI]: 1.002-1.775) for Q4 of FPG and 1.405 (95% CI: 1.051-1.878) for Q4 of HbA1c. When the participants were divided into two categories based on the cut-off value with the maximum Youden Index of FPG or HbA1c, the ORs for high FPG (≥84 mg/dL) or high HbA1c (≥5.2% [33 mmol/mol]) were 1.223 (95% CI: 1.000-1.496) and 1.392 (95% CI: 1.122-1.728), respectively. When both FPG and HbA1c were included in the model simultaneously, the statistical significance of Q4 of FPG disappeared, whereas that of HbA1c remained. In two-category models, the same results were obtained. High FPG and HbA1c levels at <24 weeks of gestation were risk factors for HDP in pregnant Japanese women. In addition, high HbA1c levels were more strongly associated with HDP than high FPG levels.

Maternal birth weight is an indicator of preterm delivery: the Japan environment and children's study.

This study aimed to investigate the association between maternal birth weight (MBW) with preterm delivery (PTD) in the Japanese population. To this end, a total of 78,972 Japanese pregnant women were included in a prospective birth cohort study. Multiple logistic regression and multinominal logistic regression models were applied to investigate the associations of MBW with PTD (delivery from 22 to < 37 weeks of gestation), early PTD (delivery from 22 to < 34 weeks), and late PTD (delivery from 34 to < 37 weeks). The results showed that MBW was inversely associated with PTD, early PTD, and late PTD (p-for-trend < 0.0001, 0.0014, and < 0.0001, respectively). The adjusted odds ratios per each 500 g of MBW decrease were 1.167 (95% confidence interval [CI]: 1.118-1.218) for PTD, 1.174 (95% CI: 1.070-1.287) for early PTD and 1.151 (95% CI: 1.098-1.206) for late PTD. The effect size of the association of MBW with early PTD was similar to that with late PTD. This study demonstrated for the first time an association of a low MBW with PTD, early PTD, and late PTD in a Japanese nationwide cohort.

Prenatal coparenting and attachment style in Japanese pregnant women: A cross-sectional survey.

Developing prenatal coparenting is important for preparing couples for parenting immediately after childbirth, but knowledge of prenatal coparenting remains limited. Adult attachment style has been shown to be one of the factors during pregnancy that predict coparenting after childbirth, as well as a significant factor in the developmental process of the coparenting relationship. The present study mainly examines the relationship between prenatal coparenting as perceived by pregnant women and their attachment style. A cross-sectional survey was conducted at a tertiary emergency medical facility in Japan. Data from 181 pregnant women at 22-36 weeks' gestation who completed a self-reported questionnaire consisting of the Prenatal Coparenting Scale (PCS), relationship-specific attachment styles, and characteristics were subjected to analysis. The mean age of the women in this study was 33.1 years (standard deviation = 5.2), 80 (44.2%) were expecting their first child, and 101 (55.8%) were expecting their second or subsequent child. Women's attachment avoidance toward their mother (r = -.26), father (r = -.23), and partner (r = -.60) and attachment anxiety toward their partner (r = -.33) were significantly negatively correlated with PCS scores. When classified into two groups by fetal birth order, attachment avoidance and attachment anxiety toward the partner were significantly negatively correlated with PCS scores, regardless of fetal birth order. Unlike attachment style toward the partner, attachment avoidance toward the mother (r = -.33) and father (r = -.32) was significantly negatively correlated with PCS scores in the group of women expecting their second or subsequent child only. These results provide valuable insights into the relationship between prenatal coparenting and adult attachment style and deepen the understanding of prenatal coparenting. Future studies using longitudinal surveys and multivariate analyses could present relevant suggestions for specific types of support that promote the development of prenatal coparenting.

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

BackgroundLow 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. AimsThis 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 subjectsThe 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 measuresLBW 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 conclusionsA 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.

Urinary concentrations of environmental phenol among pregnant women in the Japan Environment and Children’s Study

Humans are exposed to various bisphenols, alkylphenols and nitrophenols through dietary intake, food packaging and container materials, indoor and outdoor air/dust. This study aimed to evaluate exposure of Japanese pregnant women to environmental phenols by measuring target compounds in urine samples. From a cohort of the Japan Environment and Children’s Study, 4577 pregnant women were selected. Bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF), bisphenol AF (BPAF), para-nitrophenol (PNP), 3-methyl-4-nitrophenol (PNMC), branched 4-nonylphenol (4-NP), linear 4-nonylphenol and 4-tert-octylphenol (4-t-OP) were analysed using a high-performance liquid chromatograph coupled to a triple-quadrupole mass spectrometer. The urinary metabolite data were combined with a questionnaire to examine the determinants of phenol exposure by machine learning. The estimated daily intake (EDI) and hazard quotient (HQ) of BPA were calculated. PNP (68.2%) and BPA (71.5%) had the highest detection frequencies, with median concentrations of 0.76 and 0.46 μg/g creatinine, respectively. PNMC, BPS, BPF and 4-NP were determined in 24.9%, 11.9%, 1.3% and 0.4% of samples, respectively, whereas BPAF (0.02%) and 4-t-OP (0.02%) were only determined in a few samples. The PNP concentrations measured in this study were comparable with those reported in previous studies, whereas the BPA concentrations were lower than those reported previously worldwide. The EDI of BPA was 0.014 μg/kg body weight/day. Compared with the tolerable daily intake set by the German Federal Institute for Risk Assessment, the median (95th percentile) HQ was 0.044 (0.2). This indicates that the observed levels of BPA exposure pose a negligible health risk to Japanese pregnant women. Determinants of bisphenol and nitrophenol exposure could not be identified by analysing the questionnaire solely, suggesting that biological measurement is necessary to assess exposure of pregnant women to bisphenols and nitrophenols. This is the first study to report environmental phenol exposure of Japanese pregnant women on a nationwide scale.

The impact of maternal and paternal birth weights on infant birth weights: the Japan environment and children's study.

This study aimed to evaluate the association between parental and infant birth weights in Japan. In total, 37,504 pregnant Japanese women and their partners were included in this birth cohort study. A multinomial logistic regression model was used to evaluate the associations of parental birth weights with small-for-gestational-age (SGA) or large-for-gestational-age (LGA) infants. Associations between parental birth weight and low birth weight (LBW) infants or macrosomia were also examined, and linear associations between parental birth weight and SGA or LGA were found. The adjusted odds ratios (aORs) for SGA infants per 500 g decrease in maternal and paternal birth weights were 1.50 (95% confidence interval [CI],1.43-1.58) and 1.31 (95% CI, 1.25-1.38), respectively. The aORs for LGA infants per 500 g increase in maternal and paternal birth weights were 1.53 (95% CI, 1.47-1.60) and 1.41 (95% CI, 1.35-1.47), respectively. The association between parental birth weight and LBW infants or macrosomia was also linear. The aORs for LBW infants per 500 g decrease in maternal and paternal birth weights were 1.47 (95% CI, 1.40-1.55) and 1.25 (95% CI, 1.19-1.31), respectively. The aORs for macrosomia per 500 g increase in maternal and paternal birth weights were 1.59 (95% CI, 1.41-1.79) and 1.40 (95% CI, 1.23-1.60), respectively. Parental birth weight was found to be associated with infant birth weight even after adjusting for various parental factors. Furthermore, maternal birth weight was more strongly associated with infant birth weight than with paternal birth weight.

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 whethermaternal 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.

Feasibility and Usability of the Job Adjustment Mobile App for Pregnant Women: Longitudinal Observational Study.

Working pregnant women often need to adjust their physically demanding jobs for a healthy pregnancy. However, uncertainty about the extent of these adjustments can hinder their effectiveness. To address this, we developed the Job Adjustment mobile app, which allows users to input job and health details to generate a variety of personalized action plans. As this is the first version of the app, assessing its feasibility and usability is crucial. This study aims to verify the feasibility and usability of the Job Adjustment mobile app. A longitudinal observational study was conducted on pregnant Japanese women who were allowed to use the app anytime from 12 to 34 weeks of gestation; they received reminder emails every 2 weeks encouraging app use. A questionnaire was administered before app use and at 20 and 32 weeks of gestation. Feasibility was evaluated across 4 domains: implementation, demand, acceptability, and adverse events. Implementation was evaluated based on 3 parameters: dropout rate, initial reminder email receipt rate, and adherence rate (measured as pregnant women who used the app at intervals of 2.5 weeks or less). Demand was measured by intervals between use and intervals between log-in, and participants answered 15 questions to assess acceptability. Adverse events were assessed by analyzing the degree of anxiety related to work. Demographic data were analyzed to determine any statistically significant differences in intervals between uses. Usability was evaluated using the System Usability Scale. The analysis included 66 pregnant women, and 61% (n=40) of them were multipara. The dropout rate, adherence rate, and initial reminder email receipt rate were 18% (13/71), 44% (29/66), and 79% (52/66) respectively. The median intervals between use and intervals between log-in were 2.94 (IQR 2.00-5.13) weeks and 2.28 (IQR 1.81-4.00) weeks, respectively. Overall, 60% (35/58) to 90% (52/58) of the participants responded positively to all 15 questions assessing acceptability, and no anxiety regarding work was recorded. The mean System Usability Scale score was 66.1 points. Multipara women had significantly longer intervals between app use compared to primipara women (P=.01). The results demonstrated acceptable levels of feasibility and usability of the app. However, the low adherence rates, especially among multipara women, suggest the need for modifications to reduce the time burden of the app. Further research should explore more effective and acceptable intervals between use and timing, involving a larger sample and accounting for diverse characteristics of pregnant women. UMIN Clinical Trials Registry UMIN000042943; https://tinyurl.com/ydrchfas.