Association of maternal pre-pregnancy weight, weight gain during pregnancy, and smoking with small-for-gestational-age infants 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.

Characteristics of women who dropped out from pregnancy register in Okinawa, Japan: Findings from a retrospective cohort study

AIM

There is little evidence regarding women who cannot register live births after pregnancy. We aimed to clarify the difference in baseline characteristics between women who registered live births and those who did not (i.e., dropout).

METHODS

We assessed the birth cohort data of 1976 Japanese women who registered their pregnancies between July 2013 and March 2014 in Naha and Urasoe City, Okinawa, Japan. The database consisted of anthropometric data, reproductive history, sociodemographic characteristics, and dietary intake. We estimated the prevalence ratio to examine the associations of baseline characteristics with dropout by multivariable-adjusted Poisson regression with robust standard error estimation.

RESULTS

We identified 272 dropouts (13.8%) in the pregnancy registry. About 15% of women reported experience of alcohol drinking preceding 1 month of pregnancy registration. Most participants' vitamin B1 (92.1%) and folate (74.7%) consumption was inadequate considering the dietary reference intake for Japanese pregnant women, but it was not associated with a high prevalence of dropout. The prevalence of dropout was significantly higher in teenagers (prevalence ratio [PR] = 2.06, 95% confidence interval [CI] 1.38-3.07) and early 20s (PR = 1.42, 95% CI 1.04-1.93) than in women in late 20s. In addition, alcohol consumption was potentially associated with a high prevalence of dropout (adjusted prevalence ratio [aPR] = 1.31, 95% CI 0.99-1.73). Participants who experienced one or more live births (aPR = 0.43, 95% CI 0.28-0.66) were less likely to dropout.

CONCLUSION

We found that the potential risk factors for dropout from pregnancy registration were young maternal age, no childbirth experience, and alcohol consumption.

Effect of maternal smoking during pregnancy on gestational weight gain and birthweight: A stratified analysis by pregestational weight status

INTRODUCTION

METHODS

RESULTS

CONCLUSIONS

Maternal pre-pregnancy underweight and the risk of small-for-gestational-age in Asian-American ethnic groups

Objective

This study aimed to examine the association between maternal pre-pregnancy underweight and the risk of small-for-gestational-age (SGA) birth among Asian Americans compared with non-Hispanic (NH) whites.

Methods

Using 2014–2018 birth data, we categorized maternal underweight and SGA according to severity. Bivariate analyses were performed to examine the demographics and maternal body mass index (BMI). Adjusted logistic regression models were used to analyze the association between maternal BMI and SGA among Asian Americans compared with NH-Whites.

Results

In Asian Americans, the likelihood of SGA birth was higher among underweight mothers than among mothers with a normal BMI (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.30-1.46). We observed that as the severity of maternal underweight increased, the adjusted odds of SGA increased. Underweight Asian American mothers were more likely to give birth to SGA infants than underweight NH-White mothers (OR, 1.36; 95% CI, 1.28-1.44).

Conclusion

This study shows the association between maternal underweight and SGA birth among Asian Americans, supporting the development of culture-sensitive interventions addressing the impact of weight on pregnancy.

Passively inhaled tobacco smoke - pregnancy and neonatal outcomes in correlation with placental histopathology

INTRODUCTION

We aimed to investigate the effect of maternal passive smoking (MPS) during pregnancy-on placental pathology and pregnancy outcomes.

METHODS

A prospective case-control study. We recruited low-risk laboring women at 37+0-41 + 0 weeks between 9/2019-7/2020. MPS was defined as exposure to in-house spouse tobacco smoking of >20 cigarettes/day in the absence of maternal active-smoking. In attempt to "purify" the effect of MPS on placental pathology-we excluded cases with preeclampsia, diabetes, suspected fetal growth restriction (FGR), preterm labor, and illicit drug use. Maternal characteristics, pregnancy outcomes, and placental pathology were compared between the MPS group and a control group matched for gestational age, maternal age, and delivery date. Placental lesions were classified according to the "Amsterdam" criteria. The study was powered to detect a 33% difference in placental malperfusion lesions. Multivariable regression was performed to identify independent associations with placental malperfusion lesions.

RESULTS

In labor, the MPS group (n = 115) had higher rates of meconium stained amniotic fluid (MSAF, p < 0.001) and non-reassuring fetal heart-rate (NRFHR,p = 0.006), compared to controls (n = 115). Neonates in the MPS group had higher rates of undiagnosed FGR (p = 0.01) and NICU admissions (p = 0.004). The MPS group had higher rates of placental-hypoplasia (p = 0.02) and fetal vascular malperfusion (FVM) lesions (p = 0.04). In regression analysis MPS was associated with FVM lesions independent of background confounders (aOR = 1.24 95% CI 1.10-2.65).

DISCUSSION

In otherwise low-risk pregnancies, MPS was associated with higher rates of MSAF, NRFHR, undiagnosed FGR, and NICU admissions, probably mediated via placental FVM. These worrisome findings mandate patient counseling and further investigation in larger population-based studies.

Stratified analysis of the correlation between gestational weight gain and birth weight for gestational age: a retrospective single-center cohort study in Japan

BACKGROUND

Japan has an exceptionally high proportion of low-weight births and underweight women. It has been suggested that an appropriate increase in gestational weight gain (GWG) for underweight women will help to prevent low birth weight. The current strategy aims to raise the desired value of GWG equally for all pregnant women within the underweight category. However, it remains elusive whether or not the relationship between GWG and birth weight for gestational age (BW/GA) are uniformly equivalent for all the women.

METHODS

We performed a retrospective cohort analysis of women who delivered their newborns at Tokyo Medical and Dental University Hospital from 2013 to 2017. First, in order to examine the direct effect of an increase or decrease in GWG on BW/GA, we analyzed the correlation between inter-pregnancy differences in GWG and BW/GA using a sub-cohort of women who experienced two deliveries during the study period (n = 75). Second, we dichotomized the main cohort (n = 1114) according to BW/GA to verify our hypothesis that the correlation between GWG and BW/GA differs depending on the size of the newborn.

RESULTS

The inter-pregnancy difference in BW/GA was not correlated with that of GWG. However, the correlation between BW/GA of siblings was high (r = 0.63, p = 1.9 × 10^- 9). The correlation between GWG and BW/GA in women who delivered larger-sized newborns was higher (r = 0.17, p = 4.1 × 10^- 5) than that in women who delivered smaller-sized newborns (r = 0.099, p = 1.9 × 10^- 2). This disparity did not change after adjustment for pre-pregnancy BMI. The mean birth weight in the dichotomized groups corresponded to percentile 52.0 and 13.4 of the international newborn size assessed by INTERGROWTH-21st standards.

CONCLUSIONS

In our study, GWG was positively correlated with BW/GA for heavier neonates whose birth weights were similar to the average neonatal weight according to world standards. However, caution might be required for low-birth-weight neonates because increased GWG does not always result in increased birth weight.

Maternal serum uric acid levels in pregnancy and fetal growth

Objective: Studies of maternal serum uric acid (UA) in pregnancy focus primarily on high levels of UA, however, both low and high UA levels can be markers of oxidative stress, a biological state potentially linked to fetal growth. We therefore aimed to test whether low and high maternal serum UA levels during pregnancy are associated with atypical fetal growth (unusually small or large) measured as birthweight (BW) for gestational age.Methods: The Pregnancy Outcomes and Community Health Study enrolled 3019 pregnant women between their 16th-27th week of pregnancy from 52 clinics in five Michigan communities (1998-2004). Maternal UA levels were measured in blood collected at enrollment among a subcohort of 1291 participants. Infant BW and gestational age were used to calculate gestational age-specific BW Z-score. Infants were grouped as small (SGA = BW < 10th percentile), appropriate (AGA = BW 10th-90th percentile), or large (LGA) = BW > 90th percentile) for their gestational age. Analyses considered multiple potential confounders. Linear spline or multiple linear regression models were applied to evaluate the relationship between maternal UA levels and BW Z-score overall and within SGA, AGA, and LGA groups. Model robustness was tested through bootstrap, sensitivity analysis, and cross-validation techniques.Results: The relation between maternal UA levels and BW Z-score varied by infant group. Among SGA infants, the relation was nonlinear (J-shape): both extremes of UA had lower BW Z-score with a breakpoint of 0.267 mmol/L UA (adjusted regression coefficient β = 2.32, p = .01 for lower UA; adjusted β = -37.38, p < .01 for higher UA). Among AGA infants, there was no significant association, and among LGA infants, the relation was linear (adjusted β = 2.86, p = .03).Conclusions: Future research on maternal UA levels in pregnancy may benefit from considering both very low and high levels, and identifying in utero conditions associated with the two extremes.

Negative Temperature Differential in Preterm Infants Less Than 29 Weeks Gestational Age: Associations With Infection and Maternal Smoking

BACKGROUND

Hypothermia is related to increased morbidity and mortality in very preterm infants; continuous temperature monitoring is necessary. Thermoregulation is limited in preterm infants.

OBJECTIVES

The purpose of the research was to assess and describe negative temperature differential (NTD) and assess the associations of NTD with infant demographic characteristics, medical history, and clinical events.

METHODS

An exploratory, case study design was used. Abdominal and foot temperature was measured every minute over the first 2 weeks of life in 22 preterm infants at less than 29 weeks gestational age.

RESULTS

All infants experienced NTD. Daily NTD in all infants across all study days ranged from 0 to 70.7%; 2-week mean NTD over all infants ranged from 7.3% to 38.5%. Four infants treated for late onset of infection had a higher NTD than 18 infants without infection (M = 27.8%, SD = 9.52 vs. M = 16.4%, SD = 5.34, p < .05). Although not statistically significant, higher mean percentage of NTD was noted in infants having early onset infection (24.1% vs. 16.4%), African American race (20.0% vs. 15.3%), and/or being born to a mother who smoked during pregnancy (26.6% vs. 16.7%).

DISCUSSION

A larger study is needed to examine associations between NTD and race, maternal smoking history, and infection. NTD might be used as a biomarker to guide acute clinical care and identify infants at risk for acute and chronic morbidity.

Associations of maternal pre-pregnancy body mass index and gestational weight gain with birth outcomes in Shanghai, China

Recent data suggests that abnormal maternal pre-pregnancy body mass index (BMI) or gestational weight gain (GWG) is associated with unfavorable delivery outcomes. However, limited clinical evidence is available to support this correlation in China. Participating 510 mother-infant pairs were recruited from the Shanghai First Maternity and Infant Hospital, China, between January 1^st and 30^th 2016. Maternal pre-pregnancy BMI was categorized according to the China’s classification and GWG according to the 2009 Institute of Medicine recommendations (IOM). Linear regression tested the associations between pre-pregnancy BMI or GWG and length of gestation, birthweight, length, and head circumference. Logistic regression assessed the associations between pre-pregnancy BMI or GWG and macrosomic, small- (SGA) and large- (LGA) for-gestational-age infants. Overweight/obese women showed increased length of gestation and birthweight, but did not have a higher risk of macrosomic and LGA infants compared with normal weight women. Women with excessive GWG showed increased length of gestation, birthweight, length, and head circumference, and were more likely to deliver macrosomic and LGA infants compared with women with adequate GWG. Although a relatively low proportion of women from Shanghai area are overweight/obese or exhibit excessive GWG, both high pre-pregnancy BMI and excessive GWG influence perinatal outcomes.

The effects of maternal smoking on pregnancy outcome and placental histopathology lesions

OBJECTIVE

To study the effects of maternal smoking on pregnancy outcome and placental histopathology findings.

MATERIALS & METHODS

Maternal and labor characteristics and pathological reports were compared between term placentas of complicated and uncomplicated pregnancies of: heavy smokers (>10 cigarettes per day, H-smokers), moderate smokers (<10 cigarettes per day, M-smokers) and non-smokers (controls, N-smokers).

RESULTS

Birth-weights were lower in the H-smokers and M-smokers as compared to the N-smokers (p<0.001), with a higher rate of small for gestational age (SGA): 18.2%, 19.2% and 11.4%, respectively (p=0.01). Deliveries among smokers were characterized by higher rates of abnormal fetal heart rate tracings during labor as compared to non-smokers (p=0.01). Rates of placental maternal and fetal stromal-vascular supply lesions was similar between the groups.

CONCLUSIONS

Maternal smoking is associated with higher rates of SGA. Tobacco's potential influence is probably through the disruption of normal placental epigenetic patterns, not expressed in placental histopathology lesions.