Associations of maternal pre-pregnancy underweight with small-for-gestational-age and spontaneous preterm birth, and optimal gestational weight gain in Japanese women

Pre-pregnancy body mass index and low birthweight: Secondary data analysis using health insurance claims data in Japan

AIM

For women, being underweight increases their susceptibility to osteoporosis, anemia, and other conditions and affects the weight of their infants and the well-being of future generations. This study examined the association between low pre-pregnancy body mass index (BMI) and low birthweight using health insurance claims data and health checkup data, including weight measurements.

METHODS

We used health insurance claims data and health checkup data (JMDC, Tokyo, Japan) of women and their newborns in Japan between 2006 and 2020. We used checkup data, which included more accurate weight measurements and blood test-based diagnoses of anemia and hyperlipidemia compared to self-reported data. Maternal pre-pregnancy BMI was compared across three groups: underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5-24.9 kg/m2), and overweight (BMI ≥25.0 kg/m2). The primary outcome was low birthweight (<2500 g), and secondary outcome was preterm childbirth. Logistic regression analyses were conducted to compare outcomes in the three groups by BMI. The underweight BMI group was considered as the reference group. A subgroup analysis was performed by maternal age.

RESULTS

In total, 16 363 mothers (underweight, 3418 [21%], normal weight, 11 493 [70%], and overweight, 1452 [8.9%]) were included. The risk of primary outcome (low birthweight) was significantly lower in the normal weight group than in the underweight group (4.6% vs. 5.7%; adjusted odds ratio 0.78 [95% confidence interval: 0.65-0.96]). In the subgroup analyses, no significant differences were noted in the incidences of low birthweight and preterm childbirth between maternal age groups.

CONCLUSIONS

Pre-pregnancy BMI was associated with an increased risk of delivering low-birthweight infant. Awareness about the importance of women's pre-pregnancy health and appropriate BMI may reduce the incidence of low birthweight.

Effects of an individualized nutritional educational program in pregnant women: A randomized controlled trial in Japan

AIM

To evaluate the effectiveness of an individualized nutritional education program in promoting adequate nutrient intake in pregnant women.

METHODS

A stratified randomized controlled trial was conducted. Participants were stratified by factors affecting the primary outcome and randomly assigned to the intervention or control groups. Intervention group participants received an individualized 30-min booklet-based education program in their 2nd and 3rd trimesters; the control group received usual care. The primary outcome was protein intake after the intervention, which was compared between the intervention and control groups. Secondary outcomes included comparing the amount of increase of protein before and after the intervention. Nutrient intake was measured using a self-administered short dietary history questionnaire, and analyses of covariance and t tests were performed.

RESULTS

Of the 130 participants, 66 were assigned to the intervention group and 64 to the control group. There was no difference in protein intake between the two groups after the intervention (p = .051, 95% CI [-0.021, 12.4]). Comparing the increase in protein intake before and after intervention, the intervention group was 7.4 g/day higher than that of the control group (p = .040; F = 4.31; effect size = 0.36).

CONCLUSIONS

The primary outcome, a comparison of protein intake between the groups after the program, revealed no significant differences. However, on comparing the amount of protein increase before and after the intervention, the intervention group's increase was significantly higher than that of the control group. Results indicate the potential for individualized face-to-face interventions for pregnant women in Japan.

Weight Changes, Nutritional Intake, Food Contaminants, and Supplements in Women of Childbearing Age, including Pregnant Women: Guidelines for Interventions during the Perinatal Period from the French National College of Midwives

Adequate maternal nutrition is crucial for a healthy pregnancy and optimal fetal growth. Many women in France of childbearing age start their pregnancy in an unfavorable nutritional status. Recent studies highlight the value of paying attention to weight issues from the preconceptional period. It is important to call attention to the need for folate supplementation and to promote a varied and balanced diet throughout pregnancy to cover essential nutritional needs.

Severity of low pre-pregnancy body mass index and perinatal outcomes: the Japan Environment and Children's Study

Background

The extremes of maternal pre-pregnancy body mass index (BMI) are known to be risk factors associated with obstetric and adverse perinatal outcomes. Among Japanese women aged 20 years or older, the prevalence of underweight (BMI < 18.5 kg/m²) was 11.5% in 2019. Maternal thinness is a health problem caused by the desire to become slim. This study aimed to investigate the association between the severity of maternal low pre-pregnancy BMI and adverse perinatal outcomes, including preterm birth (PTB), low birth weight (LBW), and small-for-gestational age (SGA).

Methods

We conducted a prospective cohort study using data from the Japan Environment and Children’s Study, which recruited pregnant individuals between 2011 and 2014. Pre-pregnancy BMI was categorized as severe-moderate underweight (BMI < 16.9 kg/m²), mild underweight (BMI, 17.0–18.4 kg/m²), low-normal weight (BMI, 18.5–19.9 kg/m²), high-normal weight (BMI, 20.0–22.9 kg/m²), overweight (BMI, 23.0–24.9 kg/m²), and obese (BMI ≥ 25.0 kg/m²). The high-normal weight group was used as the reference for statistical analyses. Adjusted logistic regression was performed to evaluate the association between pre-pregnancy BMI and PTB, LBW, and SGA.

Results

Of 92,260 singleton pregnant individuals, the prevalence was 2.7% for severe-moderate underweight, 12.9% for mild underweight, and 24.5% for low-normal weight. The prevalence of adverse outcomes was 4.6% for PTB, 8.1% for LBW, and 7.6% for SGA. The adjusted odds ratios (aORs) for PTB were 1.72 (95% confidence interval [CI], 1.46–2.03) for severe-moderate underweight and 1.26 (95% CI, 1.14–1.39) for mild underweight. The aORs of LBW were 2.55 (95% CI, 2.27–2.86) for severe-moderate underweight, 1.64 (95% CI, 1.53–1.76) for mild underweight, and 1.23 (95% CI, 1.16–1.31) for low-normal weight. The aORs of SGA were 2.53 (95% CI, 2.25–2.84) for severe-moderate underweight, 1.66 (95% CI, 1.55–1.79) for mild underweight, and 1.29 (95% CI, 1.21–1.38) for low-normal weight.

Conclusions

A dose-response relationship was found between the severity of low pre-pregnancy BMI and PTB, LBW, and SGA. Even low-normal BMI (18.5–19.9 kg/m²) increased the risk of LBW and SGA. This study provides useful information for pre-conception counseling in lean individuals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04418-3.

Gestational weight gain rates in the first and second trimesters are associated with small for gestational age among underweight women: a prospective birth cohort study

Background

Despite the well-studied effects of gestational weight gain (GWG) on offspring health, little is known about the association of trimester-specific GWG with offspring birth weight among underweight pregnant women. This study aimed to explore the association of trimester-specific GWG rate with small for gestational age (SGA) in underweight women.

Methods

The GWG rate of underweight pregnant women (pre-pregnancy body mass index [BMI] lower than 18.5 kg/m²) of the Born in Guangzhou Cohort Study was calculated as the weight gain during a specific trimester divided by the corresponding duration of week. Total GWG was calculated as the weight difference between pre-pregnancy and delivery, and was categorized into inadequate, adequate, and excessive weight gain based on the 2009 Institute of Medicine (IOM) weight gain recommendation. The INTERGROWTH-21^st standards were used to define SGA. Logistic regression models were used to examine the associations of total GWG and trimester-specific GWG rates with SGA. Associations between trimester-specific GWG rates and SGA were also analyzed separately based on different total GWG categories (i.e. inadequate and adequate/excessive GWG).

Results

Of the 3839 participants, SGA births occurred in 397 (10.3%), and mean GWG was 14.9 kg (SD 3.9). A lower risk of SGA was observed among women with higher GWG rate (per 0.5 kg/week increase) during the first (adjusted OR [aOR] 0.74, 95%CI 0.57, 0.96) and second (adjusted OR [aOR] 0.40, 95%CI 0.30, 0.55) but not third trimester. Similar association between higher GWG rate during the second trimester and a decreased risk of SGA were observed among women with inadequate (< 12.5 kg) and adequate/excessive (≥12.5 kg) total GWG, respectively. Compared to women with adequate GWG rate, women with inadequate GWG rate during the second trimester had a significantly increased risk of SGA (aOR 1.58, 95% CI 1.14, 2.20).

Conclusions

Second-trimester GWG might be the key driver for the association between inadequate GWG and increased risk of SGA births in underweight women.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04433-4.

Insufficient maternal gestational weight gain and infant neurodevelopment at 12 months of age: the Japan Environment and Children's Study

Abnormal maternal gestational weight gain (GWG) increases the risk of obstetric-related complications. This investigation examined the impact of GWG on infant neurodevelopmental abnormalities at 12 months of age using the data of a nationwide Japanese cohort study. Questionnaire data were obtained from the ongoing Japan Environment and Children's Study cohort study. Maternal GWG was subdivided as below, within, or above the reference values of the Institution of Medicine pregnancy weight guidelines. The Ages and Stages Questionnaire, third edition (ASQ-3) is a parent-reported developmental screening instrument for children across five domains: communication, gross motor, fine motor, problem-solving, and personal-social. Multiple logistic regression analysis was employed to identify correlations between GWG and developmental delay defined as ASQ-3 scores of less than two standard deviations below the mean. A total of 30,694 mothers with singleton live births and partners who completed the questionnaire were analyzed. The prevalence of mothers below, within, and above the GWG guidelines was 60.4% (18,527), 32.1% (9850), and 7.5% (2317), respectively. We recorded 10,943 infants (35.7%) who were outliers in at least one ASQ-3 domain. After controlling for covariates, GWG below established guidelines was associated with a significantly higher risk of developmental delay for the communication (odds ratio [OR] 1.21, 95% confidence interval [CI] 1.09-1.34), gross motor (OR 1.14, 95% CI 1.05-1.24), fine motor (OR 1.13, 95% CI 1.04-1.24), problem-solving (OR 1.09, 95% CI 1.01-1.18), and personal-social (OR 1.15, 95% CI 1.07-1.24) domains.Conclusion: This large survey revealed a possible deleterious effect of insufficient maternal GWG on infant neurodevelopment.Trial registration: The Japan Environment and Children's Study (JECS) was registered in the UMIN Clinical Trials Registry on January 15, 2018 (number UMIN000030786). What is Known: • Inappropriate maternal gestational weight gain may cause obstetric complications and adverse birth outcomes. • Excess maternal weight gain may result in gestational diabetes, hypertension, eclampsia, caesarean delivery, and macrosomia, while insufficient maternal weight gain has been associated with pre-term birth and small for gestational age. What is New: • This study provides important information on a possible adverse effect of insufficient maternal gestational weight gain on offspring neurodevelopment at 12 months of age. • Our findings indicate a need to reconsider the optimal body mass index and gestational weight gain for women desiring pregnancy.

Association of Maternal Total Cholesterol With SGA or LGA Birth at Term: the Japan Environment and Children's Study

CONTEXT

Maternal cholesterol is important for fetal development. Whether maternal serum total cholesterol (maternal TC) levels in midpregnancy are associated with small (SGA) or large (LGA) for gestational age independent of prepregnancy body mass index (BMI) and weight gain during pregnancy is inconclusive.

OBJECTIVE

This work aimed to prospectively investigate the association between maternal TC in midpregnancy and SGA or LGA.

METHODS

The Japan Environment and Children's Study is a nationwide prospective birth cohort study in Japan. Participants in this study included 37 449 nondiabetic, nonhypertensive mothers with singleton birth at term without congenital abnormalities. Birth weight for gestational age less than the 10th percentile and greater than or equal to the 90th percentile were respectively defined as SGA and LGA by the Japanese neonatal anthropometric charts.

RESULTS

The mean gestational age at blood sampling was 22.7 ± 4.0 weeks. After adjustment for maternal age, sex of child, parity, weight gain during pregnancy, prepregnancy BMI, smoking, alcohol drinking, blood glucose levels, household income, and study areas, 1-SD decrement of maternal TC was linearly associated with SGA (odds ratio [OR]: 1.20; 95% CI, 1.15-1.25). In contrast, 1-SD increment of maternal TC was linearly associated with LGA (OR: 1.13; 95% CI, 1.09-1.16). Associations did not differ according to prepregnancy BMI and gestational weight gain (P for interaction > .20).

CONCLUSION

Maternal TC levels in midpregnancy were associated with SGA or LGA in a Japanese cohort. It may help to predict SGA and LGA. Favorable maternal lipid profiles for fetal development must be explored.

Risk of neural tube defects according to maternal body mass index: a systematic review and meta-analysis

INTRODUCTION

The aim of our systematic review and meta-analysis was to evaluate the risk of neural tube defects (NTDs) according to the pre-pregnancy body mass index.

MATERIALS AND METHODS

Electronic databases were searched (MEDLINE, EMBASE, Web of Sciences, Scopus, ClinicalTrial.gov, OVID, and Cochrane Library). Selection criteria included prospective and retrospective cohort studies reporting the prevalence of fetal NTDs in obese, overweight, and underweight pregnant women. Odds ratios (ORs) comparing risk among these subsets of pregnancies with normal weight mothers were determined with 95% confidence intervals (CI). The evaluated outcome was the association between maternal underweight, overweight, and obesity and the risk of NTDs.

RESULTS

We included ten studies published between 2000 and 2017, including underweight, overweight, and obese pregnant women with fetal NTD (cases) and pregnant women with recommended BMI with fetal NTD (controls). Compared with normal BMI women, obese mothers were at significantly higher risk of fetal NTDs (0.53 vs. 0.33%; OR 1.62 95% CI 1.32-1.99, p < .0001), while no difference for the risk of NTDs was found when comparing overweight (0.34 vs. 0.32%; OR 1.09 95% CI 0.92-1.3, p = .3) and underweight (0.65 vs. 0.24%; OR 1.34 95% CI 0.73-2.47, p = .34) with normal weight pregnant women.

DISCUSSION

Obese pregnant women are at significantly higher risk NTDs, while no significant difference has been found in overweight and underweight pregnant women. Key message Obese pregnant women are at significantly higher risk of NTDs, such as spina bifida compared with normal weight women. No difference was found when comparing overweight and underweight with normal weight women.

Maternal Serum Albumin Redox State Is Associated with Infant Birth Weight in Japanese Pregnant Women

Background: Plasma albumin (ALB) reflects protein nutritional status in rats, but it is not clear whether it is associated with dietary protein insufficiency in pregnant women and/or their risk of low birth weight delivery. This study aimed to investigate whether maternal serum ALB redox state reflects maternal protein nutritional status and/or is associated with infant birth weights. Methods: The relationship between the serum reduced ALB ratio and infant birth weight was examined in an observational study of 229 Japanese pregnant women. A rat model simulating fetal growth restriction, induced by protein-energy restriction, was used to elucidate the relationship between maternal nutritional status, maternal serum ALB redox state, and birth weight of the offspring. Results: In the human study, serum reduced ALB ratio in the third trimester was significantly and positively correlated with infant birth weight. In the rat study, serum reduced ALB ratio and birth weight in the litter decreased as the degree of protein-energy restriction intensified, and a significant and positive correlation was observed between them in late pregnancy. Conclusions: Maternal serum reduced ALB ratio in the third trimester is positively associated with infant birth weight in Japanese pregnant women, which would be mediated by maternal protein nutritional status.

Maternal characteristics and neonatal outcomes of emergency repeat caesarean deliveries due to early-term spontaneous labour onset

BACKGROUND

The optimal timing of elective repeat caesarean delivery has yet to be determined. One of the reasons to schedule an elective repeat caesarean delivery before 39 weeks gestation is to avoid emergency caesarean delivery due to spontaneous onset of labour.

AIMS

By ascertaining maternal characteristics and neonatal outcomes associated with early-term onset of spontaneous labour, we aim to determine the optimal timing for each individual repeat caesarean delivery.

MATERIALS AND METHODS

We performed a retrospective analysis of women with repeat caesarean deliveries planned at 38 weeks gestation between 2005 and 2019 at a tertiary referral hospital in Japan. A multivariate logistic regression analysis was adopted to identify independent contributing factors for early-term spontaneous labour onset. We also compared the rate of neonatal adverse events between women who underwent emergency repeat caesarean deliveries due to the onset of early-term labour and the ones who underwent elective repeat caesarean deliveries at 38 weeks.

RESULTS

We included 1152 women. History of vaginal deliveries (adjusted odds ratio (AOR), 2.12; 95% confidence interval (95% CI), 1.21-3.74), history of preterm deliveries (AOR, 2.28; 95% CI, 1.38-3.77), and inadequate maternal weight gain during pregnancy (AOR, 1.78; 95% CI, 1.15-2.75) significantly increased the risk of early-term spontaneous labour onset. In terms of occurrence rate of neonatal complications, we found no significant difference between the groups.

CONCLUSION

These maternal factors are significant predictors for early-term labour onset of repeat caesarean deliveries. The onset of early-term labour did not increase the likelihood of neonatal complications.

Examining the trimester-specific effects of low gestational weight gain on birthweight: the BOSHI study

Low gestational weight gain (GWG) is a known risk factor of low birthweight. Although studies have previously examined the associations between GWG and birthweight, the period-specific effects of low GWG in each trimester remain unclear. This study aimed to quantify the trimester-specific direct effects of low GWG in Japanese women on birthweight. Using perinatal data from a cohort study, we analyzed pregnant women delivered at an obstetrics/gynecology hospital between October 2006 and May 2010. We focused on women with a pre-pregnancy body mass index (BMI) below 25 kg/m2. The exposure was low GWG. The gestation period was subdivided into trimesters, and the direct effects of low trimester-specific GWG on birthweight were estimated using marginal structural models. These models were guided by a direct acyclic graph that incorporated potential confounders, including pre-pregnancy BMI, age, smoking during pregnancy, height, and parity. We analyzed 563 women and their families. The mean cumulative GWG by the end of the first, second, and third trimesters was 0.9, 6.2, and 10.7 kg, respectively. Approximately 14.0% of the women gained total weight below the range recommended by Japanese Ministry of Health, Labour and Welfare. The direct effects of low GWG on birthweight were 65.9 g (95% confidence interval: 11.4, 120.5), -195.4 g (-263.4, -127.4), and -188.8 g (-292.0, -85.5) for the first, second, and third trimesters, respectively. Insufficient weight gain in the second and third trimesters had a negative impact on birthweight after adjusting for pre-pregnancy BMI and other covariates.

Optimal gestational weight gain for underweight pregnant women in Japan

We aimed to investigate the optimal range of gestational weight gain (GWG) for Japanese underweight (body mass index <18.5 kg/m²) women using the Japanese Birth Registry System. The study subjects included underweight women who were divided into groups according to the GWG recommendations of the Ministry of Health, Labour and Welfare (MHLW) (9–12 kg): <9.0 kg, group A; 9–12 kg, group B; and >12 kg, group C. The subjects were then classified according to the recommendations of the Institute of Medicine (IOM) (12.7–18.1 kg): <12.7 kg, group D; 12.7–18.1 kg, group E; and >18.1 kg, group F. In total, 148,135 cases were analysed. The frequencies of small for gestational age, preterm delivery, and caesarean delivery were as follows: 19.3%, 22.7%, and 28.5% for group A; 11.7%, 8.7%, and 22.8% for group B; 8.0%, 4.9%, and 21.5% for group C; 15.0%, 14.7%, and 25.2% for group D; 8.0%, 5.3%, and 21.5% for group E; and 7.0%, 5.5%, and 25.0% for group F, respectively. These results indicated that groups C and E had the best outcomes. Therefore, the IOM guidelines seem more appropriate than the MHLW guidelines. Therefore, the MHLW recommended GWG guidelines require revision.

Application of Japanese guidelines for gestational weight gain to multiple pregnancy outcomes and its optimal range in 101,336 Japanese women

This study was performed to investigate whether the Japanese guidelines for gestational weight gain (GWG) can be used to determine the risks of multiple pregnancy outcomes and estimate optimal GWG in 101,336 women with singleton pregnancies in 2013. Multivariable logistic regression analyses indicated that the risks associated with low birth weight, small for gestational age, and preterm birth increased significantly with weight gain below the Japanese guidelines, and the risks of macrosomia and large for gestational age increased with weight gain above the guidelines regardless of Asian-specific pre-pregnancy body mass index (BMI). The GWG cutoff points estimated from the adjusted area under the receiver operating characteristics curve >0.6 corresponded to 10–13.8 kg in underweight women with pre-pregnancy BMI < 18.5 kg/m²; 10–13.7 kg in normal weight women with pre-pregnancy BMI 18.5–22.9 kg/m²; 8.5–11.4 kg in overweight women with pre-pregnancy BMI 23–24.9 kg/m², 5–13.3 kg in obese women with pre-pregnancy BMI 25–29.9 kg/m²; and 4.7 kg in obese women with pre-pregnancy BMI ≥ 30 kg/m². The optimal GWG ranges proposed by the present study are slightly higher than those recommended by the current Japanese guidelines.

Risk for Cesarean section in women of advanced maternal age under the changed reproductive policy in China: A cohort study in a tertiary hospital in southwestern China

AIM

To describe changed epidemiological features of advanced maternal age (AMA) and to examine the effect of AMA on the risk for Cesarean section (CS) in a Chinese pregnant population.

METHODS

This retrospective single-center cohort study investigated the changes of epidemiological features of AMA parturients with respect to the revised reproductive policy in China in 43 702 singleton deliveries with live birth at ≥28 weeks managed from January 2005 to December 2016. We also evaluated the pregnancy outcomes in different age groups and risk factors of CS with multivariate analysis.

RESULTS

In this 12-year study period, the average maternal age increased from 28.5 to 30.2 years, and the proportion of AMA raised from 6.5% to 17.2%. AMA was significantly associated with increased risk of adverse pregnancy outcomes, and after adjustment for confounding factors, AMA remained a significant independent risk factor for CS. Furthermore, the effect of AMA in nulliparous women on the risk of CS was more significant than in multiparous women, while the history of previous CS (adjusted odds ratio 39.85) and interdelivery interval ≥10 years (adjusted odds ratio 1.52) also increased the risk of CS in multiparous women.

CONCLUSION

AMA increased the risk of a number of adverse pregnancy outcomes, and was independently associated with increased risk for CS. The increasing number of AMA parturients with risk factors is likely to increase CS rate in China in the near future, thus it is imperative to reduce the rate of primary CS as a matter of policy.

Changing trends of adverse pregnancy outcomes with maternal age in primipara with singleton birth: A join point analysis of a multicenter historical cohort study in China in 2011-2012

INTRODUCTION

Adverse pregnancy outcomes are related to two opposite maternal factors, youth and aging. However, the change in trend of specific outcomes with childbearing age is unknown. The aim of this study was to investigate the changing trend of various maternal and neonatal outcomes with maternal age from 17 to 44 years.

MATERIAL AND METHODS

Data were extracted from the medical records from 2011-2012 of 39 public hospitals of 14 cities in China. The eligibility criteria were primiparity and singleton birth. Join point regression analysis was used to estimate the percent change per year of age (PCA) to explore the trends of adverse pregnancy outcomes with regard to maternal age and to identify the join point of maternal age when the trend was changed.

RESULTS

A total of 89 171 women were eligible for analysis. There were four categories of trend styles. Continuously increasing trends were linear for placenta previa (PCA, 0.1%), placenta implantation (PCA, 0.09%) and postpartum hemorrhage (PCA, 0.22%), and nonlinear for gestational diabetes mellitus with one join point of 23 years (PCA, 0.17% and 0.71%) and cesarean section with four join points of 25, 28, 31 and 36 years (PCA, 1.39%, 0.34%, 1.51%, 3.49% and 0.94%). Continuously decreasing trends were linear for intrahepatic cholestasis (PCA, -0.02%) and nonlinear for anemia with one join point of 28 years (PCA, -0.49% and -0.04%). The bidirective trends were downward to upward for preterm birth (PCA, -2.93%, -0.36% and 0.38%), hypertension in pregnancy (PCA, -0.09%, 0.47%), low birthweight (PCA 0.51% and 0.38%), low 1-minute Apgar score (PCA, -0.28% and 0.07%), low 5-minute Apgar score at (PCA, -0.10% and 0.06%) and neonatal intensive care unit admission (PCA, -1.92%, -0.07% and 0.12%) with a nadir age of 28 years. The bidirective trend was upward to downward for macrosomia (PCA, 0.39% and -0.11%), with a peak age of 30 years.

CONCLUSIONS

The changes in the trend of specific outcomes were different with maternal age, which means that youth, aging or both could affect the outcomes.

Size for gestational age at birth according to offspring sex and gestational weight gain in underweight women

Although maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) are related to fetal growth, there is a paucity of data regarding how offspring sex affects the relationship between maternal BMI in underweight mothers (pre-pregnancy BMI <18.5 kg/m2) and size for gestational age at birth. The aim of this study was to investigate the effect of offspring sex on the relationships among maternal pre-pregnancy BMI, GWG and size for gestational age at birth in Japanese underweight mothers. Records of women with full-term pregnancies who underwent perinatal care at Kawasaki Municipal Hospital (Kawasaki, Japan) between January 2013 and December 2017 were retrospectively reviewed. The study cohort included underweight (n=566) and normal-weight women (18.5 kg/m2⩽pre-pregnancy BMI<25 kg/m2; n=2671). The incidence of small for gestational age (SGA) births in the underweight group was significantly higher than that in the normal-weight group (P<0.01). Additionally, SGA incidence in the underweight group was significantly higher than that in the normal-weight group (P<0.01) in female, but not male (P=0.30) neonates. In the women with female neonates, pre-pregnancy underweight was associated with a significantly increased probability of SGA (odds ratio [OR]: 1.80; P<0.01), but inadequate GWG was not (OR: 1.38; P=0.11). In contrast, in women with male neonates, inadequate GWG was associated with a significantly increased probability of SGA (OR: 1.53; P=0.03), but not with pre-pregnancy underweight (OR: 1.30; P=0.10). In conclusion, the present results suggest that pre-pregnancy underweight is associated with SGA in female offspring but not in male offspring.

Maternal BMI in Twin Pregnancies and Impact on Neonatal Outcomes in the Level I Unit: A Retrospective Cohort Study

OBJECTIVE

With maternal obesity rates and twin pregnancies on the rise, the aim of this study was to assess the impact of pre-pregnancy or first trimester BMI on short-term neonatal morbidities in twins admitted to a level I unit.

METHODS

This retrospective single-centre cohort study was conducted on twins born between January 1, 2010 and December 31, 2013 and admitted to the level I unit at Mount Sinai Hospital in Toronto, Ontario. Twin pairs were categorized according to maternal BMI: underweight (<18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight (25.0-29.9 kg/m²), and obese (≥30 kg/m²). The primary outcome was combined neonatal morbidities of hypoglycemia and hyperbilirubinemia. The secondary outcome was length of hospital stay. All outcomes were compared between twins in various BMI groups, and data were analyzed using the chi-square test or ANOVA (Canadian Task Force Classification II-2).

RESULTS

Data on 700 neonates born to 350 women were analyzed. Baseline maternal and neonatal characteristics were similar between the groups, except for a statistically significantly higher incidence of maternal hypertension (P < 0.02) and a trend towards increased gestational diabetes rates (P = 0.05) in women with overweight or obesity compared with women with underweight or normal weight. No association was noted between maternal BMI and occurrence of neonatal hypoglycemia, hyperbilirubinemia, and length of stay in either twin pair (P > 0.05) CONCLUSION: Maternal BMI had no detectable effect on neonatal morbidities and length of stay in twins admitted to the level I unit in the study centre.

Is the risk of small for gestational age influenced by maternal body composition in young Japanese women?

Background: We aimed to investigate whether there was a high incidence of young Japanese mothers being underweight (pregravid body mass index [BMI] < 18.5 kg/m²) and if they delivered infants who were small for gestational age (SGA).Materials and methods: Our study was carried out from 2013 to 2017 and included adolescent women (maternal age at delivery: <20 years old; n = 94), women in their early twenties (maternal age at delivery: 20-24 years; n = 479), and controls (maternal age at delivery: 25-34 years; n = 2061).Results: In both the adolescent and early twenties groups, the incidence of being underweight, based on prepregnancy BMI, was significantly higher than controls (p < .0001 and p < .05, respectively). In both groups, gestational weight gain (GWG) was significantly higher than controls (p < .0001). There were no notable group differences in the incidences of SGA.Conclusion: The incidence of being underweight was higher in younger mothers than in controls. However, the risk of SGA did not increase in younger mothers, possibly because their GWG overcame the influence of their pre-pregnancy body composition.

Exposure to ambient fine particulate matter during pregnancy and gestational weight gain

BACKGROUND

Gestational weight gain (GWG) is increasingly reported to be associated with adverse birth outcomes. However, the effect of PM_2.5 exposure during pregnancy on GWG is unknown.

OBJECTIVES

We investigated the associations between the exposure to PM_2.5 and GWGs during three pregnancy trimesters based on a prospective birth cohort.

METHODS

Data were obtained from 2029 pregnant women who participated in a birth cohort between January 2013 and October 2014 in Wuhan, China. A spatial-temporal land use regression model was used to estimate the trimester and overall pregnancy exposures of PM_2.5 of each pregnant woman. The relationships between PM_2.5 exposure and GWG were estimated using linear mixed models.

RESULTS

The median value of GWG was 2.0 kg (interquartile range (IQR): 4.0) in the first trimester, 6.5 kg (IQR: 3.5) in the second trimester, and 7.0 kg (IQR: 3.5) in the third trimester, respectively. The exposure to PM_2.5 was peaked in the first trimester (median concentration: 117.3 μg/m³ (IQR: 71.9)). After adjustment for potential confounders, each 10 μg/m³ increase in PM_2.5 was consistently associated with increases in GWG in overall pregnancy (0.14 kg, 95% confidence interval (CI): 0.12, 0.17), the first (0.15 kg, 95%CI: 0.12, 0.18), second (0.15 kg, 95%CI: 0.10, 0.19) and third trimester (0.13 kg, 95%CI: 0.09, 0.17). Further stratified analysis indicated that pregnant women who delivered in spring or summer gained more body weight associated with PM_2.5 exposure.

CONCLUSIONS

This study provides evidence on the effect of exposure to PM_2.5 on GWG and it is the first report on the importance of reducing the ambient PM_2.5 in controlling of GWG in pregnant women.

Optimal weight gain in obese and overweight pregnant Japanese women

We aimed to determine the optimal gestational weight gain (GWG) in Japanese women with a Body Mass Index (BMI) ≥25 kg/m². The present retrospective study investigated singleton pregnancies in 6,781 Japanese women registered in the Japan Society of Obstetrics and Gynecology system in 2013. We divided overweight and obese women into four GWG categories based on the Institute of Medicine (IOM) recommended: weight loss, small weight gain, within IOM criteria, and above IOM criteria. The adjusted odds ratios and predicted probabilities of maternal and neonatal outcomes of interest with weight change were calculated. In overweight women, GWG was associated with neonatal birth weight. In the loss and small gain subgroups, there was a significant increase in small for gestational age (SGA) and low birth weight neonates (LBW). Predicted probabilities showed the lowest risk was observed in a weight gain of 0 kg; the risk sharply increased at a gain of 11.5 kg. In obese women, weight gain increased the prevalence of large for gestational age (LGA) neonates; however; SGA was not associated with GWG. Predicted probabilities showed an increase in the risk with weight gain. The observed optimal GWG was 0 to 11.5 kg in overweight, and weight loss in obese, pregnant Japanese women.

Gestational Weight Gain and Maternal and Neonatal Outcomes in Underweight Pregnant Women: A Population-Based Historical Cohort Study

Objective Limited data are available that estimate the effect of gestational weight gain on maternal and neonatal outcomes in underweight women according to revised 2009 Institute of Medicine (IOM) guidelines. Methods A population-based historical cohort study of 21,674 underweight women in Missouri delivering liveborn, singleton, term infants in 2002-2008 was conducted. Adjusted odds ratios were calculated for gestational weight gain categories with multiple logistic regression, using the 2009 IOM recommended 28-40 pounds as the reference group. Results Women gaining >40 pounds compared to women gaining 28-40 pounds had significantly higher odds for preeclampsia (aOR 1.94, 95% CI 1.56-2.42, p < 0.001), cesarean delivery (aOR 1.40, 95% CI 1.28-1.53, p < 0.001), large-for-gestational-age (LGA) infant (aOR 2.32, 95% CI 2.00-2.70, p < 0.001), and 1 min APGAR score <4 (aOR 1.36, 95% CI 1.01-1.83, p < 0.05) and significantly lower odds for small-for-gestational-age (SGA) infant (aOR 0.53, 95% CI 0.48-0.59, p < 0.001). Women gaining <28 pounds compared to women gaining 28-40 pounds had significantly higher odds for SGA infant (aOR 1.85, 95% CI 1.69-2.03, p < 0.001) and significantly lower odds for preeclampsia (aOR 0.72, 95% CI 0.53-0.96, p < 0.05) and LGA infant (aOR 0.50, 95% CI 0.39-0.63, p < 0.001). Conclusion Women gaining more than the IOM recommendation were at higher risk for many adverse outcomes, but at lower risk for SGA infants. Women gaining less than the IOM recommendation were at higher risk for SGA infants but were protective for preeclampsia and LGA infants. Prospective studies of other short- and long-term maternal/infant outcomes are needed to evaluate the efficacy of the IOM guideline.

Rate of gestational weight gain and preterm birth in relation to prepregnancy body mass indices and trimester: a follow-up study in China

Background

To evaluate the association between rate of gestational weight gain and preterm birth varying prepregnancy body mass indices and trimester.

Methods

Data from Maternal and Newborn’s Health Monitoring System on 17475 pregnant women who delivered live singletons at ≥ 28 weeks of gestation between October 2013 and September 2014 from 12 districts/counties of 6 provinces in China and started prenatal care at ≤ 12 weeks of gestation was analyzed. Gestational weight gain was categorized by rate of weight gain during the 2^nd and 3^rd trimester, based on the 2009 Institute of Medicine guidelines. Multivariable binary logistic regression models were conducted to investigate the association between rate of gestational weight gain and preterm birth stratified by prepregnancy body mass indices and trimester.

Results

Excessive weight gain occurred in 57.9 % pregnant women, and insufficient weight gain 12.5 %. Average rate of gestational weight gain in 2^nd and 3^rd trimester was independently associated with preterm birth (U-shaped), and the association varied by prepregnancy body mass indices and trimesters. In underweight women, excessive gestational weight gain was positively associated with preterm birth (OR 1.93, 95 % confidence interval (CI): 1.29- 2.88) when compared with women who gained adequately. While in overweight/obese women, insufficient gestational weight gain was positively associated with preterm birth (OR 3.92, 95 % CI: 1.13–13.67). When stratifying by trimester, we found that excessive weight gain in 3^rd trimester had a significantly positive effect on preterm birth (OR 1.27, 95 % CI: 1.02–1.58).

Conclusions

Excessive gestational weight gain among underweight pregnant women, insufficient gestational weight gain among overweight/obese women and excessive gestational weight gain in 3^rd trimester were important predictors of preterm birth.

Pregnancy Outcomes Based on Pre-Pregnancy Body Mass Index in Japanese Women

OBJECTIVE

To verify whether body mass index (BMI) classification proposed by the Institute of Medicine (IOM) is valid in Japanese women.

METHOD

A study was conducted in 97,157 women with singleton pregnancies registered in the Japan Society of Obstetrics and Gynecology (JSOG) Successive Pregnancy Birth Registry System between January 2013 and December 2013, to examine pregnancy outcomes in four groups stratified by pre-pregnancy BMI category according to the 2009 criteria recommended by the Institute of Medicine (IOM). The groups comprised 17,724 underweight women with BMI <18.5, 69,126 normal weight women with BMI 18.5-24.9, 7,502 overweight women with BMI 25-29.9, and 2,805 obese women with BMI ≥30. The pregnancy outcomes were also compared among subgroups stratified by a gestational weight gain below, within, and above the optimal weight gain.

RESULTS

The higher the pre-pregnancy BMI, the higher the incidences of pregnancy-induced hypertension, gestational diabetes mellitus, macrosomia, cesarean delivery, postpartum hemorrhage, and post-term birth, but the lower the incidence of small for gestational age (SGA). In all pre-pregnancy BMI category groups, excess gestational weight gain was associated with a higher frequency of large for gestational age and macrosomia; poor weight gain correlated with a higher frequency of SGA, preterm birth, preterm premature rupture of membranes, and spontaneous preterm birth; and optimal weight gain within the recommended range was associated with a better outcome.

CONCLUSION

The BMI classification by the IOM was demonstrated to be valid in Japanese women.

Inequalities in Nutrition between Cambodian Women over the Last 15 Years (2000-2014)

This study aimed to describe the trends over four nationally representative Demographic Health Surveys (2000, 2005, 2010, and 2014) of the nutritional status of women of reproductive age in Cambodia and to assess the main factors of inequality with regards to nutrition. The prevalence of undernutrition and over-nutrition evolved in opposite trends from 2000 to 2014, with a significant decrease in underweight and a significant increase in overweight women. This results in a shift, with overweight prevalence in women being higher than underweight for the first time in 2014. Anemia was constantly high and still affected 45% of women in 2014. Multivariate analysis showed that age, wealth index, maternal education, number of children, year of survey, and anemia were contributing factors for being underweight. Being overweight was positively related to increase in age, wealth index, number of children, and year of survey; and negatively related to anemia and increase in education level. The risk of anemia was higher in the poorest households and for less-educated women and women living in rural areas. Consequently, policies should target the most vulnerable women, especially the youngest, and support integrated interventions in the health, social, and agriculture sectors to reduce inequalities in nutrition between women.

Prevalence of very low birthweight, malformation, and low Apgar score among newborns in Brazil according to maternal urban or rural residence at birth

AIM

Adverse birth outcomes are a major public health issue in rural areas, where several environmental risk factors, including pesticides, may endanger the health of women of reproductive age. We investigated the prevalence of selected birth outcomes among newborns from mothers living in urban and rural areas of a Brazilian municipality.

METHODS

Information about all live births that occurred between 2004 and 2006 in the Municipality of Nova Friburgo, Brazil, was retrieved from the Live Birth Information System. Newborns were classified as rural or urban, according to the mother's residence address.

RESULTS

Newborns from rural areas had a higher prevalence of very low-birthweight, low Apgar score, and malformation. On Poisson regression with adjustment for several confounders, rural offspring were more likely to have the aforementioned outcomes.

CONCLUSIONS

Women in rural areas are at higher risk of giving birth to an infant with very low-birthweight, low 5-min Apgar score and malformations detectable at birth, regardless of socioeconomic and gestational conditions.

Folic acid supplementation, preconception body mass index, and preterm delivery: findings from the preconception cohort data in a Chinese rural population

BACKGROUND

Folic acid (FA) supplementation before and during the first trimester can reduce the risk of occurrence of preterm delivery (PTD). Preconception body mass index (BMI) is also associated with PTD. This study aimed to investigate the combined effect of FA supplements and preconception BMI on the risk of PTD.

METHODS

The data of a cohort from 2010-2011 that was obtained through a preconception care service in China was used (including 172,206 women). A multivariable regression model was used to investigate the association between maternal preconception conditions and the risk of PTD. The interaction of preconception BMI and FA supplementation was measured by a logistic regression model.

RESULTS

Taking FA supplements in the preconception period or in the first trimester reduced the risk of PTD (odds ratio [OR] = 0.58 and OR = 0.61, respectively). Women with an abnormal BMI had an increased risk of PTD (OR = 1.09, OR = 1.10, and OR = 1.17 for underweight, overweight, and obese, respectively). Preconception BMI showed an interaction with the protective effect of FA supplementation for PTD. With regard to the interaction of FA supplementation, the adjusted odds ratio (aOR) was 0.57 (95% CI: 0.51, 0.64) in underweight women, 0.85 (95% CI: 0.73, 0.98) in overweight women, and 0.77 (95% CI, 0.65, 0.91) in obese women. Preconception BMI also showed an interaction with the time of FA supplementation. Women with a normal BMI who began to take FA supplements in the preconception period had the lowest risk of PTD (aORs: 0.58 vs. 0.65 beginning in the first trimester). The aORs at preconception and the first trimester in the underweight group were 0.56 vs. 0.60. The aORs at preconception and the first trimester were 0.94 vs. 0.65 and 1.15 vs. 0.60 in the overweight and obesity groups, respectively.

CONCLUSIONS

In our study, FA supplements reduced the risk of PTD, while abnormal BMI raised the risk of PTD, although higher BMI categories did not have this higher risk once adjusted analysis was conducted. The protective effect of FA supplementation for PTD was reduced in women with overweight or obesity. To get better protection of FA supplementation, women with normal BMI or underweight should begin to use in preconception, while women with overweight or obesity should begin to use after conception.