Prepregnancy body size, gestational weight gain, and risk of preterm birth in African-American women

Maternal pre-pregnancy body mass index and risk of preterm birth: a collaboration using large routine health datasets

BACKGROUND

Preterm birth (PTB) is a leading cause of child morbidity and mortality. Evidence suggests an increased risk with both maternal underweight and obesity, with some studies suggesting underweight might be a greater factor in spontaneous PTB (SPTB) and that the relationship might vary by parity. Previous studies have largely explored established body mass index (BMI) categories. Our aim was to compare associations of maternal pre-pregnancy BMI with any PTB, SPTB and medically indicated PTB (MPTB) among nulliparous and parous women across populations with differing characteristics, and to identify the optimal BMI with lowest risk for these outcomes.

METHODS

We used three UK datasets, two USA datasets and one each from South Australia, Norway and Denmark, together including just under 29 million pregnancies resulting in a live birth or stillbirth after 24 completed weeks gestation. Fractional polynomial multivariable logistic regression was used to examine the relationship of maternal BMI with any PTB, SPTB and MPTB, among nulliparous and parous women separately. The results were combined using a random effects meta-analysis. The estimated BMI at which risk was lowest was calculated via differentiation and a 95% confidence interval (CI) obtained using bootstrapping.

RESULTS

We found non-linear associations between BMI and all three outcomes, across all datasets. The adjusted risk of any PTB and MPTB was elevated at both low and high BMIs, whereas the risk of SPTB was increased at lower levels of BMI but remained low or increased only slightly with higher BMI. In the meta-analysed data, the lowest risk of any PTB was at a BMI of 22.5 kg/m2 (95% CI 21.5, 23.5) among nulliparous women and 25.9 kg/m2 (95% CI 24.1, 31.7) among multiparous women, with values of 20.4 kg/m2 (20.0, 21.1) and 22.2 kg/m2 (21.1, 24.3), respectively, for MPTB; for SPTB, the risk remained roughly largely constant above a BMI of around 25-30 kg/m2 regardless of parity.

CONCLUSIONS

Consistency of findings across different populations, despite differences between them in terms of the time period covered, the BMI distribution, missing data and control for key confounders, suggests that severe under- and overweight may play a role in PTB risk.

Is BMI a Useful Indicator of Prenatal Health Among Black American Women?

OBJECTIVE

BMI is commonly used to measure risk to prenatal health but may not be sensitive to adiposity-associated health problems for Black women. The aim of the present study was to test associations between indices of prenatal health and BMI in Black women.

METHODS

Data were from 652 women enrolled in two studies. Height and weight were used to calculate BMI. Depression and perceived stress were measured via maternal report, systemic inflammation via C-reactive protein (CRP), and nutrition by the ratio of omega-3 docosahexaenoic acid to omega-6 arachidonic acid fatty acids.

RESULTS

Neither perceived stress, depression, nor fatty acids were associated with prenatal BMI. CRP levels were positively associated with BMI (beta = 6.56, t = 13.30, p < .001). The prevalence of high-risk levels of CRP (> 3 mg/L) was below 10% for all weight classes except for BMI ≥ 40.

CONCLUSIONS

Results suggest that BMI may not be a sensitive index of adiposity related risk to prenatal health for Black women.

Gestational Weight Gain Below Instead of Within The Guidelines per Class of Maternal Obesity: A Systematic Review and Meta-Analysis of Obstetrical and Neonatal Outcomes

OBJECTIVE

To systematically investigate a wide range of obstetrical and neonatal outcomes with respect to gestational weight gain (GWG) below the current IOM and ACOG guidelines compared to within the guidelines and to stratify outcomes by the class of obesity and by the type of study analysis.

DATA SOURCES

We systematically searched studies on PubMed, Scopus, Embase, and Cochrane Library from 2009 to April 30, 2021.

STUDY ELIGIBILITY CRITERIA

Studies reporting on obstetrical and neonatal outcomes of singleton pregnancies with respect to GWG below the current IOM and ACOG guidelines compared to within the guidelines, investigated in obesity overall (BMI> 30 kg/m²), and/or class of obesity (I: BMI 30-34.9 kg/m², II: BMI 35-39.9 kg/ m² and III: BMI> 40 kg/m²).

METHODS

Among the studies that met criteria, multiple obstetrical and neonatal outcomes were tabulated and compared between pregnancies with weight gain below the guidelines and those with weight gain within the guidelines, further classified by the class of obesity if applicable. Primary outcomes included small for gestational age (SGA), large for gestational age (LGA), preeclampsia (PE), and gestational diabetes mellitus (GDM). Secondary outcomes included cesarean section (CS), preterm birth (PTB), postpartum weight retention, and composite neonatal morbidity. Meta-analysis of univariate and adjusted multivariate analysis studies were conducted. The random-effect model was used to pool the mean differences or odds ratios (OR) and the corresponding 95% confidence intervals (CIs). Heterogeneity was assessed using the I² value. Newcastle Ottawa Scale (NOS) was used to assess individual study quality.

RESULTS

Total of 54 studies reporting on 30,245,946 pregnancies were included, of which 11,515,411 pregnancies were in the univariate analysis and 18,730,535 pregnancies in the adjusted multivariate analysis. In the meta-analysis of univariate studies, compared to women who gained within the guidelines, those who gained below the guidelines had higher odds for SGA in obesity class I and II (OR:1.30 (95% CI 1.17, 1.45), I² 0%, P<0.00001, and OR: 1.56 (95% CI 1.31, 1.85), I² 0%, P<0.00001), respectively), however, the incidence of SGA was below the expected limits (<10%) and was not associated with increased neonatal morbidity. Furthermore, after adjusting for covariates, that difference was no statistically significant anymore. The difference was not statistically significant for class III obesity. Following adjusted multivariate analysis, no significant differences in SGA rates were noted for all classes of obesity between groups. Significantly lower odds for LGA were seen in GWG below guidelines in obesity class I, II, and III (OR: 0.69 (95% CI 0.64, 0.73), I² 0%, P<0.00001, OR: 0.68 (95% CI 0.63, 0.74), I² 0%, P<0.00001, and OR: 0.65 (95% CI 0.57, 0.75), I² 34%, P<0.00001, respectively), and similar findings were seen in the adjusted multivariate analysis. Women with weight gain below guidelines had significantly lower odds for PE in obesity class I, II, and III (OR: 0.71 (95% CI 0.63, 0.79),), I² 0%, P<0.00001, OR: 0.82 (95% CI 0.73, 0.91), I² 0%, P<0.00001, and OR: 0.82 (95% CI 0.70, 0.94), I² 0%, P=0.006, respectively), and similar findings were seen in the adjusted multivariate analysis. No significant differences were seen in GDM between groups. Regarding PTB, available univariate analysis studies only reported on overall obesity and mixed iatrogenic and spontaneous PTB showing significant increase in the odds of PTB (OR: 1.42 (95% CI 1.40, 1.43), I² 0%, P<0.00001) in women with low weight gain, while adjusted multivariate studies in overall obesity and in all three classes and showed no significant differences of PTB between groups. Women with low weight gain had significantly lower odds for CS in obesity class I, II, and III (OR: 0.76 (95% CI 0.72, 0.81), I² 0%, P<0.00001, OR: 0.82 (95% CI 0.77, 0.87), I² 0%, P<0.00001, and OR: 0.87 (95% CI 0.82, 0.91), I² 0%, P<0.00001, respectively), and similar findings were seen in the adjusted multivariate analysis. There was significantly lower odds for postpartum weight retention (OR: 0.20 (95% CI 0.05, 0.82)), I² 0%, P=0.03) and lower odds for composite neonatal morbidity in the overall obesity group with low GWG (OR: 0.93 (95% CI 0.87, 0.99)), I² 19.6%, P=0.04).

CONCLUSION

Contrary to previous reports, the current systematic review and meta-analysis showed no significant increase in SGA rates in pregnancies with weight gain below the current guidelines for all classes of maternal obesity. Furthermore, gaining below the guidelines was associated with lower LGA, PE, and CS rates. Our study provides the evidence that the current recommended GWG is high for all classes of obesity. These results provide pertinent information supporting the notion to revisit the current GWG recommendations for women with obesity and furthermore to classify them by the class of obesity rather than one overall obesity category as is done in the current recommendations.

Waist Circumference Measurement for Prediction of Preeclampsia: A Population-Based Cohort Study

BACKGROUND

Identifying women at high risk for preeclampsia is essential for the decision to start treatment with prophylactic aspirin. Prediction models have been developed for this purpose, and these typically incorporate body mass index (BMI). As waist circumference (WC) is a better predictor for metabolic and cardiovascular outcomes than BMI in nonpregnant populations, we aimed to investigate if WC is a BMI-independent predictor for preeclampsia and if the addition of WC to a prediction model for preeclampsia improves its performance.

METHODS

We used a population-based cohort of 4,696 women with WC measurements taken in the first trimester. The influence of WC on the risk of developing preeclampsia was evaluated by multivariable logistic regression. We generated receiver operating characteristic curves and calculated the area under the curve (AUC) to evaluate the usefulness of WC measurements for prediction of preeclampsia.

RESULTS

Women who developed preeclampsia had greater early pregnancy WC than women who did not (85.8 ± 12.6 vs. 82.3 ± 11.3 cm, P < 0.001). The risk of preeclampsia increased with larger WC in a multivariate model, adjusted odds ratio 1.02 (95% confidence interval 1.01-1.03). However, when adding BMI into the model, WC was not independently associated with preeclampsia. The AUC value for preeclampsia prediction with BMI and the above variables was 0.738 and remained unchanged with the addition of WC to the model.

CONCLUSIONS

Large WC is associated with a higher risk of preeclampsia, but adding WC to a prediction model for preeclampsia that already includes BMI does not improve the model's performance.

Explaining the Black-White Disparity in Preterm Birth: A Consensus Statement From a Multi-Disciplinary Scientific Work Group Convened by the March of Dimes

In 2017-2019, the March of Dimes convened a workgroup with biomedical, clinical, and epidemiologic expertise to review knowledge of the causes of the persistent Black-White disparity in preterm birth (PTB). Multiple databases were searched to identify hypothesized causes examined in peer-reviewed literature, 33 hypothesized causes were reviewed for whether they plausibly affect PTB and either occur more/less frequently and/or have a larger/smaller effect size among Black women vs. White women. While definitive proof is lacking for most potential causes, most are biologically plausible. No single downstream or midstream factor explains the disparity or its social patterning, however, many likely play limited roles, e.g., while genetic factors likely contribute to PTB, they explain at most a small fraction of the disparity. Research links most hypothesized midstream causes, including socioeconomic factors and stress, with the disparity through their influence on the hypothesized downstream factors. Socioeconomic factors alone cannot explain the disparity's social patterning. Chronic stress could affect PTB through neuroendocrine and immune mechanisms leading to inflammation and immune dysfunction, stress could alter a woman's microbiota, immune response to infection, chronic disease risks, and behaviors, and trigger epigenetic changes influencing PTB risk. As an upstream factor, racism in multiple forms has repeatedly been linked with the plausible midstream/downstream factors, including socioeconomic disadvantage, stress, and toxic exposures. Racism is the only factor identified that directly or indirectly could explain the racial disparities in the plausible midstream/downstream causes and the observed social patterning. Historical and contemporary systemic racism can explain the racial disparities in socioeconomic opportunities that differentially expose African Americans to lifelong financial stress and associated health-harming conditions. Segregation places Black women in stressful surroundings and exposes them to environmental hazards. Race-based discriminatory treatment is a pervasive stressor for Black women of all socioeconomic levels, considering both incidents and the constant vigilance needed to prepare oneself for potential incidents. Racism is a highly plausible, major upstream contributor to the Black-White disparity in PTB through multiple pathways and biological mechanisms. While much is unknown, existing knowledge and core values (equity, justice) support addressing racism in efforts to eliminate the racial disparity in PTB.

Association of Prepregnancy Nutritional Status and Physical Activity Levels with Birth Size Outcomes among West Sumatran Pregnant Women: Results from the Vitamin D Pregnant Mothers Cohort Study in Indonesia

Background: Maternal and neonatal morbidity is still high in developing countries like in Indonesia. There are several factors may affect maternal health during pregnancy such as physical activity level (PAL) and pre-pregnancy nutritional status. Aim: To analyze the association between maternal physical activity status (PAL) and pre-pregnancy body mass index (PP BMI) with birth size outcomes. Methods: A prospective birth cohort study, Vitamin D Pregnant Mothers (VDPM) Study, to 183 healthy singleton pregnant women. Pre-pregnancy body mass index was classified according to WHO guidelines for Asian Population. Women PAL was measured at the first trimester (T1) and third trimester (T3) during pregnancy using the Global Physical Activity Questionnaire (GPAQ). Birth size outcomes were measured immediately after birth such as birth weight, birth length, and head circumference. Results: Pregnant women at T3 had two times lower physical activity than T1 of pregnancy (OR, 2.18; CI, 1.044-4.57; p = 0.045). Maternal PAL at T1 and T3 were mostly in sedentary level (74.3% and 77.1%, respectively). There was no association between PP BMI, PAL, and birth size outcomes (p > 0.05 for all comparisons). However, the physical activity at T1 had a significant association with birth weight outcomes [MD (95%CI): 155.3 (13.8 – 296.8), p = 0.032]. There was a significant interaction between maternal PAL and PP BMI on birth weight (p interaction = 0.011) and head circumference (p interaction = 0.034). Conclusions: Our study reveals that pre-maternal nutritional status and physical activity behavior during the pregnancy associated with the head circumference and birth weight outcomes. Further large studies are needed to confirm our findings.

Exploration of Diet Quality by Obesity Severity in Association with Gestational Weight Gain and Distal Gut Microbiota in Pregnant African American Women: Opportunities for Intervention

OBJECTIVE

To conduct an exploratory examination of dietary patterns and quality during pregnancy in African-American women who were class I, II, or III obese, and those women with normal pre-pregnancy body mass index (pBMI), as well to identify dietary factors associated with GWG, and changes in the distal gut microbiome. African American women represent the largest group affected by pre-pregnancy obesity, a risk factor for several adverse birth outcomes.

METHODS

This prospective study investigated the association between diet, distal gut microbiome, and GWG among African-American women (n = 21) with obesity (n = 15) compared to women with a normal pre-pregnancy body mass index (pBMI) (n = 6) at two time points, 27-29 and 37-39 weeks gestation. Dietary patterns associated with obesity severity and GWG gain were assessed using Welch's T-test and Mann-Whitney U. The association between the gut microbiome and dietary patterns was assessed using a regression-based kernel association test and the adaptive microbiome-based sum of powered score test.

RESULTS

In early pregnancy, dietary intake of Total Fruits and Greens and Beans was significantly different between pBMI and GWG groups; significance was 0.022 and 0.028 respectively. Women with Class II/III obesity and those with GWG above guidelines had Healthy Eating Index (HEI) scores below 50, meeting less than 75% of dietary guidelines, and did not meet recommendations for fruit and vegetable or fiber intake. We found no significant associations between the microbiome composition and diet (HEI Scores).

CONCLUSIONS FOR PRACTICE

Overall, the results indicate that women with pBMI obesity are not meeting minimum dietary guidelines for nutrient intakes during pregnancy, specifically fruits, vegetables, and fiber, regardless of GWG. Interventions for African-American women with pre-pregnancy obesity, with a focus on increasing consumption of fruits and vegetables, would be beneficial to control GWG and improve birth outcomes.

Collateral Damage: Maternal Obesity During Pregnancy Continues to Rise

Importance

The pandemic of obesity during pregnancy now afflicts 1 out of every 2 pregnant women in the United States. Even though unintended pregnancy has decreased to 45% of all pregnancies, 50% of those unintended pregnancies occur in obese women.

Objective

This study aims to identify why current lifestyle interventions for obese pregnancy are not effective and what the newer complications are for obesity during pregnancy.

Evidence Acquisition

Available literatures on current treatments for maternal obesity were reviewed for effectiveness. Emerging maternal and infant complications from obesity during pregnancy were examined for significance.

Results

Limitations in successful interventions fell into 3 basic categories to include the following: (1) preconception weight loss; (2) bariatric surgery before pregnancy; and (3) prevention of excessive gestational weight gain during pregnancy. Emerging significant physiological changes from maternal obesity is composed of inflammation (placenta and human milk), metabolism (hormones, microbiome, fatty acids), and offspring outcomes (body composition, congenital malformations, chronic kidney disease, asthma, neurodevelopment, and behavior).

Conclusions and Relevance

Are current prepregnancy lifestyle and behavioral interventions feasible to prevent maternal obesity complications? Epigenetic and metabolomic research will be critical to determine what is needed to blunt the effects of maternal obesity and to discover successful treatment.

Timing and Amount of Gestational Weight Gain in Association with Adverse Birth Outcomes

BACKGROUND

Most existing research on gestational weight gain and pregnancy outcomes has not accounted for timing of weight gain. The area under the weight gain curve (AUC) provides a single measure that incorporates both timing of weight gain and total amount gained. This study evaluated predictors and outcomes associated with second- and third-trimester weight gain AUC from the second and third trimester using time-to-event analysis to account for the correlation between gestational weight gain and gestational duration.

METHODS

Our prospective cohort study used data from the LifeCodes study at Brigham and Women's Hospital. Maternal weights were available from all prenatal and study visits. We used log-Poisson models with empirical variance estimation to identify predictors of total AUC from 14 weeks to delivery and Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between AUC quintile and adverse pregnancy outcomes.

RESULTS

Compared to the middle quintile, the highest quintile of accumulated pound-days was associated with a decreased hazard of spontaneous preterm birth among multigravid women (HR = 0.44; 95% CI = 0.23, 0.84), a decreased hazard of small-for-gestational-age births (HR = 0.65; 95% CI = 0.45, 0.92) overall and an increased hazard of large-for-gestational-age births among normal and underweight women (HR = 3.21; 95% CI = 1.50, 6.89) CONCLUSIONS:: In our study, a pattern of gestational weight gain characterized by more rapid gains earlier in pregnancy was associated with improved pregnancy outcomes in some subgroups of pregnant women.

Elevated body mass index during pregnancy and gestational weight gain in HIV-infected and HIV-uninfected women in Cape Town, South Africa: association with adverse birth outcomes

OBJECTIVES

To examine the association between maternal body mass index (BMI) and gestational weight gain (GWG) and adverse birth outcomes in HIV-infected and HIV-uninfected women.

METHODS

In an urban South African community, 2921 consecutive HIV-infected and HIV-uninfected pregnant women attending primary healthcare services were assessed at their first antenatal visit. A subset of HIV-infected women enrolled in a longitudinal study was assessed three times during pregnancy. All women had birth outcome data from medical records and study questionnaires. In analyses, the associations between BMI, GWG, maternal factors and adverse birth outcomes were assessed with logistic regression models.

RESULTS

The estimated pre-pregnancy BMI median was 29 kg/m2 (IQR, 24-34) overall, 29 kg/m2 (IQR, 24-34) for HIV-uninfected and 28 kg/m2 (IQR, 24-34) for HIV-infected women; HIV prevalence was 38%. In adjusted models, increased BMI in the overall cohort was positively associated with age, haemoglobin and parity at first antenatal visit. Maternal obesity was associated with increased likelihood of having high birthweight (aOR 2.54, 95% CI 1.39-4.66) and large size for gestational age (aOR 1.66, 95% CI 1.20-2.31) infants. In the subset cohort, GWG was associated with increased likelihood of spontaneous preterm delivery (aOR 4.35, 95% CI 1.55-12.21) and high birthweight (aOR 3.00, 95% CI 1.22-7.34) infants.

CONCLUSION

Obesity during pregnancy is prevalent in this setting and appears associated with increased risk of adverse birth outcomes in both HIV-infected and HIV-uninfected women. Weight management interventions targeting women of child-bearing age are needed to promote healthy pregnancies and reduce adverse birth outcomes.

Using the theoretical domains framework to explore primary health care practitioner's perspectives and experiences of preconception physical activity guidance and promotion

Preconception physical activity is one of the main predictors of continued engagement in physical activity during and after pregnancy and subsequently, improves the health of women and their child. In the UK, guidance states that Primary Care health Professionals (PCPs) should assess and discuss the lifestyle of preconception women, in routine appointments, in order to address potentially modifiable risk factors. However, knowledge and provision of this guidance in the UK is unknown. It is not clear if individuals actively seek preconception guidance from PCPs, what guidance they request, and whether PCPs have the knowledge and skills to provide this support in line with current guidelines. This research aimed to explore current practice and the perspectives of PCPs in delivering physical activity guidance to preconception patients. Fifteen semi-structured interviews were conducted with PCPs (GPs and community pharmacists) in the UK. Data was analysed using the Theoretical Domains Framework (TDF). Our findings showed patients did not frequently present solely for preconception physical activity guidance, but occasionally enquired when consulting about another issue. PCPs lacked motivation to implement physical activity guidance due to the perception that their advice would have no impact on behaviour change. There were a number of perceived opportunities to implement preconception physical activity guidance. These findings illustrate the need for consistent and specific preconception lifestyle and PA guidance for PCPs.

Pre-pregnancy BMI, gestational weight gain and birth outcomes in Lebanon and Qatar: Results of the MINA cohort

Accumulating evidence has highlighted the role of maternal nutritional status on fetal development, birth outcomes and child health. The Mother and Infant Nutritional Assessment (MINA) cohort is a 3-year follow-up study of pregnant women and their children in Qatar and Lebanon. This study reports on the characteristics and determinants of pre-pregnancy BMI and Gestational Weight Gain (GWG) of MINA particiants, as well as birth outcomes. A total of 272 pregnant women were recruited during their first trimester from primary healthcare centers as well as private clinics in Beirut (n = 194) and Doha (n = 147). During the first visit, data collection included pre-pregnancy weight, sociodemographic and lifestyle characteristics. The weight before delivery and neonatal outcomes were extracted from the medical records. GWG was calculated as the difference between weight before delivery and pre-pregnancy weight and was classified into insufficient, adequate, and excessive, as per the IOM criteria. Overall, 42.1% of women had a pre-pregnancy BMI≥25 Kg/m² (58% in Qatar vs 30.8% in Lebanon, p<0.001). Only 30.2% of women had adequate GWG, while 25.7% and 44.1% of women had insufficient and excessive GWG, respectively. In the cohort 68.7% of infants had a weight adequate-for-gestational age (AGA), 6.7% were SGA and 24.6% were LGA. The proportions of LGA were higher with greater GWG (p<0.05). After adjustment, Qatari women were 3 times more likely to be overweight or obese before pregnancy while a higher education level was associated with significantly lower odds of pre-pregnancy BMI≥25 Kg/m². Pre-pregnancy BMI≥25 Kg/m² and regular breakfast consumption were predictors of excessive GWG (OR: 3.20, CI: 1.48–6.91; OR: 2.84, CI: 1.15–7.02, respectively). The high prevalence of pre-pregnancy overweight and excessive GWG among MINA participants underscores the need for culture-specific intervention programs to promote healthy body weight in women of childbearing age, and prevent excessive weight gain during pregnancy.

[An investigation of physical development of 5 027 neonates in Urumqi, China]

OBJECTIVE

To investigate the physical development of Uygur and Han neonates in Urumqi, China.

METHODS

Live singleton neonates with a gestational age of 28-42 weeks who were born in the First Affiliated Hospital of Xinjiang Medical University and Maternal and Child Health Care Hospital from December 2014 to May 2017 were enrolled, and their body weight, body length, head circumference, and chest circumference at birth were measured. The cubic curve fitting method was used to plot the smooth curves of body weight, body length, head circumference, and chest circumference.

RESULTS

A total of 5 027 singleton neonates with a gestational age of 28-42 weeks were enrolled, with 2 625 boys and 2 402 girls. The average values of birth weight, body length, head circumference, and chest circumference, Quetelet index, and Ververck index of Uygur/Han boys and girls with a gestational age of 28-42 weeks were obtained, and related smoothed percentile curves were plotted. There were some differences between Uygur and Han neonates in the average values of some growth and development indices. The Quetelet index and the Ververck index of Uygur and Han neonates increased with the increase in gestational age, and the Uygur neonates had a higher Ververck index than the Han neonates.

CONCLUSIONS

There are differences in the levels of some growth and development indices and Ververck index between the Uygur and Han neonates in Urumqi. The average values of body weight, body length, chest circumference, and head circumference at birth, Quetelet index, and Ververck index of Uygur and Han neonates with a gestational age of 28-42 weeks and their smoothed percentile curves can provide a reference for the assessment of neonatal growth and development in Urumqi.

Predictors of thallium exposure and its relation with preterm birth

Thallium (Tl) is a well-recognized hazardous toxic heavy metal that has been reported to have embryotoxicity and fetotoxicity. However, little is known about its association with preterm birth (PTB) in humans. We aimed to evaluate the predictors of Tl exposure and assessed its relation with PTB. The study population included 7173 mother-infant pairs from a birth cohort in Wuhan, China. Predictors of Tl concentrations were explored using linear regression analyses, and associations of Tl exposure with risk of PTB or gestational age at birth were estimated using logistic regression or generalized linear models. The geometric mean and median values of urinary Tl concentrations were 0.28 μg/L (0.55 μg/g creatinine) and 0.29 μg/L (0.53 μg/g creatinine). We found that maternal urinary Tl concentrations varied by gestational weight gain, educational attainment, multivitamin and iron supplementations. Women with Tl concentrations higher than 0.80 μg/g creatinine were at higher risk of giving birth prematurely versus those with Tl concentrations lower than 0.36 μg/g creatinine [adjusted odds ratio (95% confidence interval (CI)): 1.55 (1.05, 2.27)], and the association was more pronounced in PTB with premature rupture of membranes (PROM) rather than in PTB without PROM. About 3-fold increase in creatinine-corrected Tl concentrations were associated with 0.99-day decrease in gestational length (95% CI: -1.36, -0.63). This is the first report on the associations between maternal Tl exposure and the risk of PTB.

Maternal Prepregnancy Weight and Children's Behavioral and Emotional Outcomes

INTRODUCTION

This study investigated associations between maternal prepregnancy BMI and child behaviors at ages 9-11 years and examine interaction by race and gender.

METHODS

The National Longitudinal Survey of Youth and the Children and Young Adults surveys are U.S.-based, ongoing longitudinal studies, initiated in 1979 and 1986, respectively. Mothers (n=2,952) reported pregnancy and child (n=5,660) developmental information at multiple time points. Child total, internalizing, and externalizing problems at ages 9-11 years were assessed using the Behavior Problems Index (BPI), collected biennially until 2012. Associations between prepregnancy BMI and child BPI outcomes were examined, as well as two- and three-way interactions by race and gender. Analyses were conducted in 2017.

RESULTS

Boys whose mothers had higher prepregnancy weights exhibited higher total BPI and externalizing scores at ages 9-11 years versus those with normal-weight mothers. Boys with severely obese mothers had higher total BPI (mean difference=7.99, 95% CI=3.53, 12.46) and externalizing (mean difference=5.77, 95% CI=1.50, 10.04) scores. Prepregnancy underweight was associated with boys' higher total BPI (mean difference=2.34, 95% CI=0.02, 4.66) and externalizing (mean difference=3.30, 95% CI=0.69, 5.91); these associations were not significant in sensitivity analyses. No associations emerged for girls or internalizing problems. Two-way interactions by race and three-way interactions by race and gender were not significant.

CONCLUSIONS

Maternal prepregnancy weight was associated with BPI level among boys. Boys with severely obese mothers exhibited markedly higher behavioral problems at ages 9-11 years versus those with normal-weight mothers, regardless of race. Maintaining healthy prepregnancy weight may be important for preventing boys' deleterious behavior outcomes in middle childhood.

Risk factors for low birth weight and preterm birth: A population-based case-control study in Wuhan, China

Low birth weight (LBW) and preterm birth (PB) are associated with newborn mortality and diseases in adulthood. We explored factors related to LBW and PB by conducting a population-based case-control study from January 2011 to December 2013 in Wuhan, China. A total of 337 LBW newborn babies, 472 PB babies, and 708 babies with normal birth weights and born from term pregnancies were included in this study. Information of newborns and their parents was collected by trained investigators using questionnaires and referring to medical records. Univariate and logistic regression analyses with the stepwise selection method were used to determine the associations of related factors with LBW and PB. Results showed that maternal hypertension (OR=6.78, 95% CI: 2.27-20.29, P=0.001), maternal high-risk pregnancy (OR=1.53, 95% CI: 1.06-2.21, P=0.022), and maternal fruit intake ≥300 g per day during the first trimester (OR=1.70, 95% CI: 1.17-2.45, P=0.005) were associated with LBW. BMI ≥24 kg/m² of mother prior to delivery (OR=0.48, 95% CI: 0.32-0.74, P=0.001) and gestation ≥37 weeks (OR=0.01, 95% CI: 0.00-0.02, P<0.034) were protective factors for LBW. Maternal hypertension (OR=3.36, 95% CI: 1.26-8.98, P=0.016), maternal high-risk pregnancy (OR=4.38, 95% CI: 3.26-5.88, P<0.001), maternal meal intake of only twice per day (OR=1.88, 95% CI: 1.10-3.20, P=0.021), and mother liking food with lots of aginomoto and salt (OR=1.60, 95% CI: 1.02-2.51, P=0.040) were risk factors for PB. BMI ≥24 kg/m² of mother prior to delivery (OR=0.66, 95% CI: 0.47-0.93, P=0.018), distance of house from road ≥36 meters (OR=0.72, 95% CI: 0.53-0.97, P=0.028), and living in rural area (OR= 0.60, 95% CI: 0.37-0.99, P=0.047) were protective factors for PB. Our study demonstrated some risk factors and protective factors for LBW and PB, and provided valuable information for the prevention of the conditions among newborns.

Racial/Ethnic Differences in Correlates of Spontaneous and Medically-Indicated Late Preterm Births among Adolescents

STUDY OBJECTIVE

To investigate the racial/ethnic differences in the correlates of spontaneous and medically-indicated late preterm birth (LPTB), defined as deliveries between 34 0/7 and 36 6/7 weeks gestation, among US adolescents.

DESIGN

Population-based, retrospective cohort study.

SETTING

Births in the United States to adolescents in 2012.

PARTICIPANTS

Adolescents (younger than 20 years; n = 171,573) who delivered nonanomalous singleton first births between 34 and 44 weeks of gestation.

INTERVENTIONS AND MAIN OUTCOME MEASURES

Bivariate and multivariable logistic regression were used to evaluate the associations between maternal risk factors and spontaneous and medically-indicated LPTB, stratified according to maternal race/ethnicity.

RESULTS

Risk factors for spontaneous LPTB included single marital status among Asian adolescents; no insurance coverage among whites, Asian, and Hispanic adolescents; inadequate prenatal care among all racial/ethnic groups except American Indian, and adequate plus prenatal care among all races/ethnicities; prenatal smoking among whites and black adolescents; insufficient gestational weight gain among all racial/ethnic groups except American Indian; and prepregnancy underweight among white, black, and Hispanic adolescents. Risk factors for medically-indicated LPTB included inadequate prenatal care among white, black, and Hispanic adolescents, and adequate plus prenatal care among all racial/ethnic groups except Asian; insufficient gestational weight gain among white, black, and Hispanic adolescents; and prepregnancy overweight and obesity among white, black, and Hispanic adolescents.

CONCLUSION

Our results show racial/ethnic differences in the correlates of spontaneous and medically-indicated LPTB among US adolescents and support the need for risk-specific interventions among different racial/ethnic groups.

Preeclampsia and Preterm Birth Associated With Visceral Adiposity in Early Pregnancy

OBJECTIVE

To determine if an increasing amount of visceral adipose tissue, measured by ultrasound in early pregnancy, is associated with a higher risk of preeclampsia and preterm birth (PTB).

METHODS

We completed a prospective cohort study of 463 pregnant women. Maternal visceral adiposity tissue (VAT) depth was measured by ultrasound at 11 to 14 weeks' gestation. Relative risks (RR) were adjusted for age, parity, chronic hypertension, pre-pregnancy BMI, and use of acetylsalicylic acid.

RESULTS

The rate of preeclampsia was much higher at quintile (Q) 5 of VAT depth (9.8%) than at Q1 to Q4 (1.6%) but not significantly so in the adjusted model (RR 3.39, 95% CI 0.86 to 13.39). The adjusted RR of PTB was significantly elevated at Q5 VAT depth (6.53, 95% CI 1.47 to 6.53), as was preeclampsia with PTB (16.91, 95% CI 1.24 to 231.07).

CONCLUSION

Higher amounts of VAT in pregnancy may play a direct role in the pathogenesis of preeclampsia, including early onset preeclampsia necessitating preterm delivery.

Gestational weight gain and preterm birth: disparities in adolescent pregnancies

OBJECTIVE

To examine racial differences in the association between gestational weight gain and preterm birth subtypes among adolescents.

STUDY DESIGN

We conducted a retrospective cohort study of 211 403 adolescents using 2012 United States natality data. The outcome was preterm birth and the primary exposure was gestational weight gain. Multinomial logistic regression analyses were used to estimate adjusted odds ratios, stratified by race and body mass index (BMI).

RESULTS

Black and White mothers who gained below the recommendations had increased risks for spontaneous preterm birth in all BMI categories, except obese. All Hispanic mothers who gained below the recommendations had increased risks of spontaneous preterm birth. White normal and overweight mothers and Black, Hispanic and Other normal weight mothers who exceeded the recommendations had decreased risks of spontaneous preterm birth.

CONCLUSION

The effect of gestational weight gain on spontaneous and medically indicated preterm birth is modified by race and BMI.

Gestational weight gain in women with systemic lupus erythematosus

Objective The objective of this study was to estimate the proportion of pregnant women with systemic lupus erythematosus meeting Institute of Medicine guidelines for gestational weight gain and determine correlates of adherence to guidelines. Methods Singleton, live births in the Hopkins Lupus Pregnancy Cohort 1987-2015 were included. Pre-pregnancy weight was the weight recorded 12 months prior to pregnancy/first trimester. Final weight was the last weight recorded in the third trimester. Adherence to Institute of Medicine guidelines (inadequate, adequate, or excessive) was based on pre-pregnancy body mass index. Fisher's exact test and analysis of variance determined factors associated with not meeting guidelines. Stepwise selection estimated predictors of gestational weight gain. Results Of the 211 pregnancies, 34%, 24% and 42% had inadequate, adequate and excessive gestational weight gain, respectively. In exploratory analyses, differences in Institute of Medicine adherence were observed by pre-pregnancy body mass index, race, elevated creatinine during pregnancy and pre-pregnancy blood pressure. Odds of inadequate and excessive gestational weight gain increased 12% with each 1 kg/m² increase in pre-pregnancy body mass index. Lower maternal education was associated with increased odds of inadequate and excessive gestational weight gain. Conclusions As in the general population, most women with systemic lupus erythematosus did not meet Institute of Medicine guidelines. Our results identified predictors of gestational weight gain to aid in targeted interventions to improve guideline adherence in this population.

Inflammatory biomarkers and spontaneous preterm birth among obese women

OBJECTIVE

To identify associations between second-trimester serum inflammatory biomarkers and preterm birth among obese women.

METHODS

In this nested case-control study, we compared 65 serum inflammatory biomarkers in obese women whose pregnancies resulted in early spontaneous preterm birth (<32 weeks gestation, n = 34) to obese women whose pregnancies resulted in term birth (n = 34). These women were selected from a larger population-based California cohort. Random forest and classification and regression tree techniques were employed to identify biomarkers of importance, and adjusted odds ratios (aORs) and 95% confidence intervals (CI) were estimated using logistic regression.

RESULTS

Random forest and classification and regression tree techniques found that soluble vascular endothelial growth factor receptor-3 (sVEGFR3), soluble interleukin-2 receptor alpha-chain (sIL-2RA) and soluble tumor necrosis factor receptor-1 (sTNFR1) were related to preterm birth. Using multivariable logistic regression to compare preterm cases and term controls, decreased serum levels of sVEGFR3 and increased serum levels of sIL-2RA and sTNFR1 were associated with increased risk of preterm birth among obese women, aOR = 3.2 (95% CI: 1.0-9.9), aOR = 2.8 (95% CI: 0.9-9.0), and aOR = 4.1 (95% CI: 1.2-14.1), respectively.

CONCLUSIONS

In this pilot study, we identified three serum biomarkers indicative of inflammation to be associated with spontaneous preterm birth among obese women: sVEGFR3, sIL-2RA and sTNFR1.

Rate of Second and Third Trimester Weight Gain and Preterm Delivery Among Underweight and Normal Weight Women

Objectives Low gestational weight gain (GWG) in the second and third trimesters has been associated with increased risk of preterm delivery (PTD) among women with a body mass index (BMI) < 25 mg/m(2). However, few studies have examined whether this association differs by the assumptions made for first trimester gain or by the reason for PTD. Methods We examined singleton pregnancies during 2000-2008 among women with a BMI < 25 kg/m(2) who delivered a live-birth ≥28 weeks gestation (n = 12,526). Women received care within one integrated health care delivery system and began prenatal care ≤13 weeks. Using antenatal weights measured during clinic visits, we interpolated GWG at 13 weeks gestation then estimated rate of GWG (GWGrate) during the second and third trimesters of pregnancy. We also estimated GWGrate using the common assumption of a 2-kg gain for all women by 13 weeks. We examined the covariate-adjusted association between quartiles of GWGrate and PTD (28-36 weeks gestation) using logistic regression. We also examined associations by reason for PTD [premature rupture of membranes (PROM), spontaneous labor, or medically indicated]. Results Mean GWGrate did not differ among term and preterm pregnancies regardless of interpolated or assumed GWG at 13 weeks. However, only with GWGrate estimated from interpolated GWG at 13 weeks, we observed a U-shaped relationship where odds of PTD increased with GWGrate in the lowest (OR 1.36, 95 % CI 1.10, 1.69) or highest quartile (OR 1.49, 95 % CI 1.20, 1.85) compared to GWGrate within the second quartile. Further stratifying by reason, GWGrate in the lowest quartile was positively associated with spontaneous PTD while GWGrate in the highest quartile was positively associated with PROM and medically indicated PTD. Conclusions Accurate estimates of first trimester GWG are needed. Common assumptions applied to all pregnancies may obscure the association between GWGrate and PTD. Further research is needed to fully understand whether these associations are causal or related to common antecedents.

Gestational weight gain and preterm birth in obese women: a systematic review and meta-analysis

BACKGROUND

Prepregnant obesity is a global concern and gestational weight gain has been found to influence the risks of preterm birth.

OBJECTIVE

To assess the relationship between gestational weight gain and risk for preterm birth in obese women.

SEARCH STRATEGY

Four electronic databases were searched from 18 February through to 28 April 2015.

SELECTION CRITERIA

Primary research reporting preterm birth as an outcome in obese women and gestational weight gain as a variable that could be compared to the 2009 Institute of Medicine's recommendations.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trials for inclusion. The Newcastle Ottawa Scale was used to assess study bias.

MAIN RESULTS

Our search identified six studies meeting the inclusion criteria; five were conducted in the USA and one in Peru. Four studies with a total of 10 171 obese women were meta-analysed. Significant heterogeneity was found between studies in the pooled analysis. Results for indicated preterm birth in obese women with gestational weight gain above the Institute of Medicine's recommendations showed increased risk (adjusted odds ratio 1.54; 95% CI 1.09-2.16).

CONCLUSIONS

Available science on this topic is limited to special populations of obese pregnant women. Generalisable research is needed to assess the variation in risk for preterm birth in obese women by differences in gestational weight gain and class of obesity controlling for significant variables in the pathway to preterm birth. This research has the potential to illuminate new science impacting preterm birth and interventions for prevention.

Pre-pregnancy body mass index, height and physical activity are associated with rate of gestational weight gain among Malaysian mothers

AIM

Both inadequate and excessive weight gain during pregnancy can have immediate and long-term health risks for women and infants. This study investigated rate of gestational weight gain (GWG) and its associated factors in Malaysian pregnant women.

METHODS

This cross-sectional study was conducted at maternal and child health clinics in Selangor and Negeri Sembilan between November 2010 and April 2012. A pre-tested questionnaire was used to obtain sociodemographic, obstetric, dietary intake and physical activity information. Current weight and height were measured using standard procedures. GWG rate was calculated as the average weekly weight gain in that particular trimester of pregnancy and further categorized according to the Institute of Medicine (IOM) recommendations.

RESULTS

Mean GWG rate for all pre-pregnancy BMI categories in the second and third trimesters was higher than the IOM recommendations. Overweight women (adjusted OR, 4.26; 95%CI: 1.92-9.44) and women <153 cm tall (adjusted OR, 1.96; 95%CI: 1.21-3.18) tend to have inadequate GWG rate. Women with high pre-pregnancy body mass index (BMI; ≥25.0 kg/m(2) ; overweight: adjusted OR, 3.88; 95%CI: 2.12-7.09; obese: adjusted OR, 2.34; 95%CI: 1.28-4.29) and low physical activity (adjusted OR, 1.74; 95%CI: 0.77-3.97) were two-threefold more likely to have excessive GWG.

CONCLUSION

Both inadequate and excessive GWG can have detrimental effects on the health of mothers and infants. Pre-pregnancy BMI, height and physical activity should be emphasized in prenatal care to ensure that women have adequate GWG rate.

Body mass index, physical activity and fecundability in a North American preconception cohort study

OBJECTIVE

To evaluate the association between adiposity, physical activity (PA), and fecundability.

DESIGN

Prospective cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 2,062 female pregnancy planners from the United States and Canada who were enrolled during the preconception period.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Self-reported pregnancy. Fecundability ratios (FRs) and 95% confidence intervals (CIs) were estimated using proportional probabilities models that adjusted for potential confounders.

RESULT(S)

Relative to body mass index (BMI) 18.5-24 kg/m(2), FRs for BMI <18.5, 25-29, 30-34, 35-39, 40-44, and ≥45 kg/m(2) were 1.05 (95% CI 0.76-1.46), 1.01 (95% CI 0.89-1.15), 0.98 (95% CI 0.82-1.18), 0.78 (95% CI 0.60-1.02), 0.61 (95% CI 0.42-0.88), and 0.42 (95% CI 0.23-0.76), respectively. Reduced fecundability was observed among women with the largest waist-to-hip ratios (≥0.85 vs. <0.75; FR = 0.87, 95% CI 0.74-1.01) and waist circumferences (≥36 vs. <26 inches [≥90 vs. <66 cm]; FR = 0.80, 95% CI 0.59-1.01). Tendency to gain weight in the chest/shoulders (FR = 0.63, 95% CI 0.36-1.08) and waist/stomach (FR = 0.90, 95% CI 0.79-1.02), relative to hips/thighs, was associated with lower fecundability. Moderate PA was associated with increased fecundability (≥5 vs. <1 h/wk; FR = 1.26, 95% CI 0.96-1.65), but there was no dose-response relation. Among overweight/obese women (BMI ≥25 kg/m(2)), fecundability was 27% higher for vigorous PA of ≥5 versus <1 h/wk (95% CI 1.02-1.57).

CONCLUSION(S)

Various measures of overall and central adiposity were associated with decreased fertility among pregnancy planners. Vigorous PA was associated with improved fertility among overweight and obese women only; moderate PA was associated with improved fertility among all women.

Maternal Microbiome and Pregnancy Outcomes That Impact Infant Health: A Review

The maternal microbiome is recognized as a key determinant of a range of important maternal and child health outcomes, and together with perinatal factors influences the infant microbiome. This article provides a summary review of research investigating (1) the role of the maternal microbiome in pregnancy outcomes known to adversely influence neonatal and infant health, including preterm birth, cardiometabolic complications of pregnancy such as preeclampsia and gestational diabetes, and excessive gestational weight gain; (2) factors with an established link to adverse pregnancy outcomes that are known to influence the composition of the maternal microbiome; and (3) strategies for promoting a healthy maternal microbiome, recognizing that much more research is needed in this area.

Racial/Ethnic Disparities in Inadequate Gestational Weight Gain Differ by Pre-pregnancy Weight

Pre-pregnancy body mass index (BMI) varies by race/ethnicity and modifies the association between gestational weight gain (GWG) and adverse pregnancy outcomes, which disproportionately affect racial/ethnic minorities. Yet studies investigating whether racial/ethnic disparities in GWG vary by pre-pregnancy BMI are inconsistent, and none studied nationally representative populations. Using categorical measures of GWG adequacy based on Institute of Medicine recommendations, we investigated whether associations between race/ethnicity and GWG adequacy were modified by pre-pregnancy BMI [underweight (<18.5 kg/m(2)), normal weight (18.5-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)), or obese (≥30.0 kg/m(2))] among all births to Black, Hispanic, and White mothers in the 1979 USA National Longitudinal Survey of Youth cohort (n = 6,849 pregnancies; range 1-10). We used generalized estimating equations, adjusted for marital status, parity, smoking during pregnancy, gestational age, and multiple measures of socioeconomic position. Effect measure modification between race/ethnicity and pre-pregnancy BMI was significant for inadequate GWG (Wald test p value = 0.08). Normal weight Black [risk ratio (RR) 1.34, 95 % confidence interval (CI) 1.18, 1.52] and Hispanic women (RR 1.33, 95 % CI 1.15, 1.54) and underweight Black women (RR 1.38, 95 % CI 1.07, 1.79) experienced an increased risk of inadequate GWG compared to Whites. Differences in risk of inadequate GWG between minority women, compared to White women, were not significant among overweight and obese women. Effect measure modification between race/ethnicity and pre-pregnancy BMI was not significant for excessive GWG. The magnitude of racial/ethnic disparities in inadequate GWG appears to vary by pre-pregnancy weight class, which should be considered when designing interventions to close racial/ethnic gaps in healthy GWG.

Effects of Prepregnancy Body Mass Index and Gestational Weight Gain on Pregnancy Outcomes

To investigate the single and joint effects of prepregnancy body mass index (BMI) and gestational weight gain (GWG) on pregnancy outcomes, electronic medical records of 14 196 women who delivered singleton live infant at a maternal and child health hospital in Beijing, China, in 2012 were reviewed. Logistic regression was used to assess the associations, adjusting for maternal age, height, education, parity, and offspring sex. Women of high prepregnancy BMI or excessive GWG had higher risks of gestational diabetes mellitus, hypertensive disorders in pregnancy, postpartum hemorrhage, caesarean delivery, macrosomia, and large for gestational age infant, while women of inadequate GWG had higher risks of preterm delivery, low birth weight, and small for gestational age infant. Findings suggest that antenatal care providers should help pregnant women control their GWG to normal.

Relationship between sociodemographics, dietary intake, and physical activity with gestational weight gain among pregnant women in Rafsanjan City, Iran

Gestational weight gain (GWG) is a determinant of health and nutrition of mothers and offspring. However, many factors associated with GWG are not completely understood. The present study assessed the relationship between sociodemographics, dietary intake, and physical activity with GWG in 308 Iranian pregnant women attending government healthcare centres in Rafsanjan city, Iran. Women gained an average of 12.87±3.57 kg during pregnancy while 54% did not gain weight within the Institute of Medicine (IOM)-recommended range. Univariate logistic models showed that gestaional weight gain was related to age, pre-pregnancy body mass index (BMI), energy intake, and sitting time. Cumulative logit model showed positive relationship between age (p=0.0137) and pre-pregnancy BMI (p<0.0001) with GWG. All pregnant women should be counselled on achieving the reccomended GWG to prevent adverse maternal and prenatal outcomes. Pre-pregnancy and gestational nutritional status and physical activity should be emphasized in antenatal care.

Exercise during pregnancy and its association with gestational weight gain

We examined the association between exercise during pregnancy and meeting gestational weight gain recommendations. Data came from the 2009 South Carolina Pregnancy Risk Assessment Monitoring System (n = 856). Women reported their participation in exercise/sports activities before and during pregnancy, including the number of months and types of exercise. We developed an exercise index (EI), the product of the number of months spent in exercise and average metabolic equivalents for specific exercise. The 2009 Institute of Medicine's guideline was used to categorize gestational weight gain into three classes: inadequate, adequate, and excessive. Multinomial logistic regression models were used to adjust for confounders. Over 46 % of women exceeded the recommended weight gain during pregnancy. Nearly one third (31.9 %) of women reported exercising ≥3 times a week at any time during pregnancy. Compared to women who did not report this level of exercise during pregnancy, exercising women were more likely to meet gestational weight gain recommendations (32.7 vs. 18.7 %) and had a lower odds of excessive gestational weight gain [adjusted odds ratio (AOR) 0.43, 95 % confidence interval 0.24-0.78]. Women with an EI above the median value of those women who exercised or women who exercised ≥3 times a week for 6-9 months during pregnancy had lower odds of excessive gestational weight gain (AOR for EI 0.20, 0.08-0.49; AOR for months 0.26, 0.12-0.56, respectively). Our findings support the need to promote or increase exercise during pregnancy to reduce the high proportion of women who are gaining excessive weight.

Pre-pregnancy BMI, gestational weight gain and postpartum weight retention: a meta-analysis of observational studies

OBJECTIVE

To determine the association of gestational weight gain (GWG) or pre-pregnancy BMI with postpartum weight retention (PPWR).

DESIGN

Meta-analysis.

SETTING

PubMed, Cochrane Controlled Trials Register, EMBASE, Science Citation Index Expanded, Current Contents Connects and Biosis Previews were used to search articles.

SUBJECTS

Publications that described the influence of pre-pregnancy BMI or GWG on PPWR.

RESULTS

Seventeen studies that satisfied the eligibility criteria were included in the analyses. Women with inadequate and excessive GWG had significantly lower mean PPWR of -2·14 kg (95 % CI -2·43, -1·85 kg) and higher PPWR of 3·21 kg (95 % CI 2·79, 3·62 kg), respectively, than women with adequate GWG. When postpartum time spans were stratified into 1-3 months, 3-6 months, 6-12 months, 12-36 months and ≥15 years, the association between inadequate GWG and PPWR faded over time and became insignificant (-1·42 kg; 95 % CI -3·08, 0·24 kg) after ≥15 years. However, PPWR in women with excess GWG exhibited a U-shaped trend; that is, a decline during the early postpartum time span (year 1) and then an increase in the following period. Meta-analysis of qualitative studies showed a significant relationship between excessive GWG and higher PPWR risk (OR=2·08; 95 % CI 1·60, 2·70). Moreover, meta-analysis of pre-pregnancy BMI on PPWR indicated that mean PPWR decreased with increasing BMI group.

CONCLUSIONS

These findings suggest that GWG, rather than pre-pregnancy BMI, determines the shorter- or longer-term PPWR.

Relationship between pre-pregnancy maternal BMI with spontaneous preterm delivery and birth weight

The aim of the present study was to find the relationship between pre-pregnancy maternal body mass index (BMI) with spontaneous preterm delivery and birth weight. A prospective cohort study was performed on 576 pregnant women. Maternal BMI was determined at the first prenatal visit between 8-12 weeks' gestation and considered as the pre-pregnancy maternal weight. The women were then monitored up to delivery. Out of 576 women, 396 completed the study. The demographics of the women in all BMI groups did not differ with regard to age, height, history of abortion and employment. A total of 21 women (5.3%) were underweight; 198 women (50%) were normal weight; 117 women (29.5%) were overweight and 60 (15.2%) were obese. There were no cases of morbidly obese (BMI > 40 kg/m(2)) women. Obesity in women had a positive correlation with higher gestational age at the time of delivery (r = 0.213, p = 0.015) and a heavier birth weight (r = 0.361, p = 0.008). Low birth weight had a correlation with low maternal BMI (r = 0.157, p = 0.041). Macrosomia was greater in obese women (p = 0.022) and BMI had a positive correlation with macrosomia (r = 0.224, p = 0.034). Preterm delivery showed a negative correlation with maternal BMI (r = -0.124, p = 0.004) and the women with a lower BMI had a greater number of preterm deliveries (p = 0.035).

Preterm birth and subsequent risk of type 2 diabetes in black women

BACKGROUND

Gestational diabetes is a precursor to type 2 diabetes. Little is known about the relation of other common pregnancy complications, such as preterm birth, to risk of type 2 diabetes.

METHODS

We assessed preterm birth in relation to incident type 2 diabetes among 31,101 participants from the Black Women's Health Study. Preterm birth, defined as <37 weeks gestation, was reported at baseline (1995) and on subsequent biennial follow-up questionnaires. Self-reported type 2 diabetes diagnoses were ascertained on biennial questionnaires through 2009. We used Cox proportional hazards models to calculate incidence rate ratios (IRRs) and 95% confidence intervals (CIs), adjusting for potential confounders.

RESULTS

At baseline, 5162 participants (19%) reported a history of giving birth preterm, of which 16% occurred at <32 weeks gestation. A total of 3261 cases of type 2 diabetes were ascertained during follow-up. Ever having had a preterm birth was associated with a 20% increased risk (95% CI = 1.11-1.31) after adjusting for age at first birth, family history of diabetes, education, respondent having been born preterm, and body mass index. Gestational age <32 weeks was associated with the greatest risk (IRR = 1.27 [95% CI = 1.06-1.51]). Among women without a history of gestational diabetes, the IRR for type 2 diabetes among women who ever had a preterm birth was 1.17 (1.07-1.28).

CONCLUSION

Preterm birth was associated with an increased type 2 diabetes risk in black mothers, independent of gestational diabetes.

Preconception care: nutritional risks and interventions

INTRODUCTION

There is increasingly a double burden of under-nutrition and obesity in women of reproductive age. Preconception underweight or overweight, short stature and micronutrient deficiencies all contribute to excess maternal and fetal complications during pregnancy.

METHODS

A systematic review and meta-analysis of the evidence was conducted to ascertain the possible impact of preconception care for adolescents, women and couples of reproductive age on maternal, newborn and child health (MNCH) outcomes. A comprehensive strategy was used to search electronic reference libraries, and both observational and clinical controlled trials were included. Cross-referencing and a separate search strategy for each preconception risk and intervention ensured wider study capture.

RESULTS

Maternal pre-pregnancy weight is a significant factor in the preconception period with underweight contributing to a 32% higher risk of preterm birth, and obesity more than doubling the risk for preeclampsia, gestational diabetes. Overweight women are more likely to undergo a Cesarean delivery, and their newborns have higher chances of being born with a neural tube or congenital heart defect. Among nutrition-specific interventions, preconception folic acid supplementation has the strongest evidence of effect, preventing 69% of recurrent neural tube defects. Multiple micronutrient supplementation shows promise to reduce the rates of congenital anomalies and risk of preeclampsia. Although over 40% of women worldwide are anemic in the preconception period, only one study has shown a risk for low birth weight.

CONCLUSION

All women, but especially those who become pregnant in adolescence or have closely-spaced pregnancies (inter-pregnancy interval less than six months), require nutritional assessment and appropriate intervention in the preconception period with an emphasis on optimizing maternal body mass index and micronutrient reserves. Increasing coverage of nutrition-specific and nutrition-sensitive strategies (such as food fortification; integration of nutrition initiatives with other maternal and child health interventions; and community based platforms) is necessary among adolescent girls and women of reproductive age. The effectiveness of interventions will need to be simultaneously monitored, and form the basis for the development of improved delivery strategies and new nutritional interventions.

Preconception care: delivery strategies and packages for care

The notion of preconception care aims to target the existing risks before pregnancy, whereby resources may be used to improve reproductive health and optimize knowledge before conceiving. The preconception period provides an opportunity to intervene earlier to optimize the health of potential mothers (and fathers) and to prevent harmful exposures from affecting the developing fetus. These interventions include birth spacing and preventing teenage pregnancy, promotion of contraceptive use, optimization of weight and micronutrient status, prevention and management of infectious diseases, and screening for and managing chronic conditions. Given existing interventions and the need to organize services to optimize delivery of care in a logical and effective manner, interventions are frequently co-packaged or bundled together. This paper highlights packages of preconception interventions that can be combined and co-delivered to women through various delivery channels and provides a logical framework for development of such packages in varying contexts.

Peso ao nascer e fatores associados ao período pré-natal: um estudo transversal em hospital maternidade de referência

O presente estudo analisou fatores relacionados ao peso ao nascer em um hospital maternidade do município do Rio de Janeiro. Trata-se de estudo seccional, descritivo, conduzido no Hospital Maternidade Herculano Pinheiro (HMHP), Rio de Janeiro, entre dezembro de 2008 e fevereiro de 2009, com puérperas entre 20 e 34 anos. Foram aplicados os testes de Qui-quadrado, t de student e modelo de regressão logística. Dos recém-nascidos, 14,6% tinham baixo peso ao nascer (inferior à 2500g). Encontrou-se correlação negativa entre o peso ao nascer e o hábito de fumar da mãe. As variáveis peso pré-gestacional, índice de massa corporal pré-gestacional materno e número de consultas no pré-natal apresentaram associação positiva com o peso ao nascer. A análise múltipla indicou a idade materna como fator de risco para o baixo peso ao nascer. Conclui-se que a situação sobre o estado civil, onde este se apresentou como uma variável importante, assim como o número de consultas pré-natal que na análise do grupo não apresentou significado estatístico, merece maior investigação com outros estudos.

Maternal prepregnancy body mass index and risk of spontaneous preterm birth

BACKGROUND

Findings from studies examining risk of preterm birth associated with elevated prepregnancy body mass index (BMI) have been inconsistent.

METHODS

Within a large population-based cohort, we explored associations between prepregnancy BMI and spontaneous preterm birth across a spectrum of BMI, gestational age, and racial/ethnic categories. We analysed data for 989,687 singleton births in California, 2007-09. Preterm birth was grouped as 20-23, 24-27, 28-31, or 32-36 weeks gestation (compared with 37-41 weeks). BMI was categorised as <18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0-34.9 (obese I); 35.0-39.9 (obese II); and ≥ 40.0 (obese III). We assessed associations between BMI and spontaneous preterm birth of varying severity among non-Hispanic White, Hispanic, and non-Hispanic Black women.

RESULTS

Analyses of mothers without hypertension and diabetes, adjusted for age, education, height, and prenatal care initiation, showed obesity categories I-III to be associated with increased risk of spontaneous preterm birth at 20-23 and 24-27 weeks among those of parity 1 in each race/ethnic group. Relative risks for obese III and preterm birth at 20-23 weeks were 6.29 [95% confidence interval (CI) 3.06, 12.9], 4.34 [95% CI 2.30, 8.16], and 4.45 [95% CI 2.53, 7.82] for non-Hispanic Whites, non-Hispanic Blacks, and Hispanics, respectively. A similar, but lower risk, pattern was observed for women of parity ≥ 2 and preterm birth at 20-23 weeks. Underweight was associated with modest risks for preterm birth at ≥ 24 weeks among women in each racial/ethnic group regardless of parity.

CONCLUSIONS

The association between women's prepregnancy BMI and risk of spontaneous preterm birth is complex and is influenced by race/ethnicity, gestational age, and parity.

Prepregnancy body mass index and risk of preterm birth: association heterogeneity by preterm subgroups

BACKGROUND

To evaluate the association between prepregnancy body mass index (BMI) is associated with early vs. late and medically-induced vs. spontaneous preterm birth (PTB) subtypes.

METHODS

Using data from the Boston Birth Cohort, we examined associations of prepregnancy BMI with 189 early (<34 completed weeks) and 277 late (34-36 completed weeks) medically-induced PTBs and 320 early and 610 late spontaneous PTBs vs. 3281 term births (37-44 weeks) in multinomial regression. To assess for mediation by important pregnancy complications, we performed sequential models with and without hypertensive disorders of pregnancy, chorioamnionitis, and gestational diabetes.

RESULTS

Prevalence of prepregnancy obesity (BMI ≥ 30.0 kg/m2) was 28% among mothers with medically-induced PTBs, 18% among mothers with spontaneous PTBs, and 18% among mothers with term births (p = <0.001). After adjustment for demographic and known risk factors for PTB, prepregnancy obesity was associated with higher odds of both early [OR 1.78 (1.19, 2.66)] and late [OR 1.49 (1.09, 2.04)] medically-induced PTB. These effect estimates were attenuated with inclusion of hypertensive disorders of pregnancy and gestational diabetes. For spontaneous deliveries, prepregnancy obesity was associated with decreased odds of PTB (0.76 [0.58, 0.98]) and underweight was nearly associated with increased odds of PTB (1.46 [0.99, 2.16]).

CONCLUSION

Prepregnancy obesity is associated with higher risk of medically-induced, but not spontaneous PTB. Hypertensive disorders of pregnancy and gestational diabetes appear to partially explain the association between prepregnancy obesity and early and late medically-induced PTB.

Association between gestational weight gain according to prepregnancy body mass index and short postpartum weight retention in postpartum women

BACKGROUND & AIMS

This study aims to assess the relationship among prepregnancy body mass index, gestational weight gain, and postpartum weight retention, and to clarify the predictors of the amount of weight retained by Chinese women after pregnancy.

METHODS

The multistage stratified random sampling was used in the cross-sectional study.

RESULTS

The subjects included 1643 women. Mean gestational weight gain was 15.9 kg and mean postpartum weight retention was 5.1 kg. 43.2% of women gained excessive gestational weight gain and 53.3% of women gained 5 kg or more postpartum weight retention. In addition, the proportions of underweight women with inadequate weight gain and overweight women with excessive weight gain were 24.2% and 52.3%, respectively. Logistic regression analysis showed that the adjusted OR of excessive gestational weight gain was 1.74 (95% CI: 1.09-2.79) in overweight women compared with normal weight women. The postpartum weight retention and the proportion of women with postpartum weight retention of 5 kg or more were significantly higher in the excessive gestational weight gain women than in the adequate gestational weight gain women in all three body mass index groups. The adjusted OR of a weight increase of 5 kg or more was at least 1.90 for underweight, normal weight, and overweight women with a gestational weight gain above the recommended amount compared with those with a gestational weight gain within the recommended amount.

CONCLUSIONS

Gestational weight gain above the recommended amount increases the risk of postpartum weight retention in all body mass index groups.

Pregnancy weight gain and childhood body weight: a within-family comparison

BACKGROUND

Excessive pregnancy weight gain is associated with obesity in the offspring, but this relationship may be confounded by genetic and other shared influences. We aimed to examine the association of pregnancy weight gain with body mass index (BMI) in the offspring, using a within-family design to minimize confounding.

METHODS AND FINDINGS

In this population-based cohort study, we matched records of all live births in Arkansas with state-mandated data on childhood BMI collected in public schools (from August 18, 2003 to June 2, 2011). The cohort included 42,133 women who had more than one singleton pregnancy and their 91,045 offspring. We examined how differences in weight gain that occurred during two or more pregnancies for each woman predicted her children's BMI and odds ratio (OR) of being overweight or obese (BMI≥85th percentile) at a mean age of 11.9 years, using a within-family design. For every additional kg of pregnancy weight gain, childhood BMI increased by 0.0220 (95% CI 0.0134-0.0306, p<0.0001) and the OR of overweight/obesity increased by 1.007 (CI 1.003-1.012, p = 0.0008). Variations in pregnancy weight gain accounted for a 0.43 kg/m(2) difference in childhood BMI. After adjustment for birth weight, the association of pregnancy weight gain with childhood BMI was attenuated but remained statistically significant (0.0143 kg/m(2) per kg of pregnancy weight gain, CI 0.0057-0.0229, p = 0.0007).

CONCLUSIONS

High pregnancy weight gain is associated with increased body weight of the offspring in childhood, and this effect is only partially mediated through higher birth weight. Translation of these findings to public health obesity prevention requires additional study. Please see later in the article for the Editors' Summary.

Risk of miscarriage among black women and white women in a U.S. Prospective Cohort Study

Many adverse pregnancy outcomes differ by race. We examined the association between self-reported race and miscarriage (pregnancy loss at <20 weeks) in a community-based pregnancy cohort. Women from the southeastern United States (North Carolina, Texas, and Tennessee) were enrolled in "Right from the Start" from 2000 to 2009. They were recruited while trying to conceive or during early pregnancy. Participants completed study ultrasound examinations, interviews, and consent forms for review of medical records. We used proportional hazard models to examine miscarriage risk among black women compared with white women, adjusted for confounders. There were 537 observed miscarriages among 4,070 women, 23% of whom self-identified as black (n = 932). The life table-adjusted cumulative risk of loss after gestational week 5 was 21.3%. With adjustment for age and alcohol use, blacks had increased risk of miscarriage compared with whites (adjusted hazard ratio = 1.57, 95% confidence interval: 1.27, 1.93). When risk of loss before gestational week 10 was dichotomized at the median gestational age, there was little difference, but black women had a greater risk thereafter compared with white women (adjusted hazard ratio = 1.93, 95% confidence interval: 1.48, 2.51). Early pregnancy ultrasound examinations did not differ by race. In summary, self-reported race is independently associated with risk of miscarriage, and the higher risk for black women is concentrated in gestational weeks 10-20.

Central adiposity and other anthropometric factors in relation to risk of macrosomia in an African American population

OBJECTIVE

Previous studies have consistently identified maternal obesity and gestational weight gain (GWG) as risk factors for macrosomia, but little is known about the effects of central adiposity and body fat distribution. Using self-reported data from the Black Women's Health Study (BWHS), a large follow-up study of US black women, we examined the risk of macrosomia in relation to prepregnancy waist circumference, prepregnancy waist-to-hip ratio (WHR), prepregnancy BMI, and GWG.

DESIGN AND METHODS

During 1995-2003, BWHS participants ages 21-44 years delivered 6,687 full-term singleton births (gestational age >37 weeks). We compared mothers of 691 infants weighing ≥ 4,000 g with mothers of 5,996 infants weighing <4,000 g. Generalized estimating equation models (GEE) that accounted for more than one birth per mother were used to estimate multivariable odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Independent of prepregnancy BMI, prepregnancy waist circumference was positively associated with risk of macrosomia (OR = 1.58, 95% CI: 1.07-2.32, for ≥ 35.0 vs. <27.0 inches (≥ 88.9 vs. <68.6 cm); P trend = 0.04). As expected, prepregnancy BMI was also positively associated with macrosomia (OR = 1.74, 95% CI: 1.25-2.41 for BMI ≥ 35.0 vs. 18.5-24.9 kg m(-2)). GWG above the amount recommended by the 2009 Institute of Medicine report was associated with an increased risk of macrosomia and the association was present in each category of prepregnancy BMI (18.5-24.9, 25.0-29.9, and ≥ 30.0 kg m(-2); P trend <0.001).

CONCLUSIONS

Our data suggest that overall obesity, high GWG, and high waist circumference are independent risk factors for macrosomia among US black women.

Association between body mass index and pregnancy outcome in a randomized trial of cerclage for short cervix

OBJECTIVE

To evaluate whether increasing body mass index (BMI) alters the efficacy of ultrasound-directed cerclage in women with a history of preterm birth.

METHODS

This was a planned secondary analysis of a multicenter trial in which women with a singleton gestation and prior spontaneous preterm birth (17 to 33 + 6 weeks' gestation) were screened for a short cervix by serial transvaginal ultrasound evaluations between 16 and 22 + 6 weeks. Women with a short cervix (cervical length < 25 mm) were randomly assigned to cerclage or not. Linear and logistic regression were used to assess the relationship between BMI and continuous and categorical variables, respectively.

RESULTS

Overall, in the screened women (n = 986), BMI was not associated with cervical length (P = 0.68), gestational age at delivery (P = 0.12) or birth at < 35 weeks (P = 0.68). For the cerclage group (n = 148), BMI had no significant effect. For the no-cerclage group (n = 153), BMI was associated with a decrease in gestational age at delivery, with an estimated slope of - 0.14 weeks per kg/m(2) (P = 0.03; including adjustment for cervical length). This result was driven primarily by several women with BMI > 47 kg/m(2) .

CONCLUSION

In women at high risk for recurrent preterm birth, BMI was not associated with cervical length or gestational age at birth. BMI did not appear to adversely affect ultrasound-indicated cerclage.

Fatores associados ao nascimento pré-termo em Campina Grande, Paraíba, Brasil: um estudo caso-controle

Estudo caso-controle (2008-2009) de base populacional que analisou fatores de risco para nascimento pré-termo em Campina Grande, Paraíba, Brasil. Foram incluídos 341 nascimentos pré-termo e 424 controles. Utilizou-se regressão logística múltipla. Foram fatores de risco: idade materna de 35 ou mais (OR = 2,00; IC95%: 1,00-4,03), pré-termo prévio (OR = 2,32; IC95%: 1,25-4,29), pré-natal inadequado (OR = 2,15; IC95%: 1,40-3,27), ganho ponderal materno insuficiente (OR = 2,33; IC95%: 1,45-3,75), dano físico materno (OR = 2,10; IC95%: 1,22-3,60), hipertensão arterial com eclampsia (OR = 17,08; IC95%: 3,67-79,43) e sem eclampsia (OR = 6,42; IC95%: 3,50-11,76), internação (OR = 5,64; IC95%: 3,47-9,15), alteração do volume amniótico (OR = 2,28; IC95%: 1,32-3,95); sangramento vaginal (OR = 1,54; IC95%: 1,01-2,34) e gestação múltipla (OR = 22,65; IC95%: 6,22-82,46). Elevada e homogênea prevalência de pobreza e baixa escolaridade pode ter contribuído para que as variáveis socioeconômicas não permanecessem com associação significativa para o nascimento pré-termo.