Low Gestational Weight Gain and Risk of Adverse Perinatal Outcomes in Obese and Severely Obese Women

Impact of Gestational Weight Gain Recommendations for Obese Women on Neonatal Morbidity

INTRODUCTION

 In 2013, the American College of Obstetricians and Gynecologists (ACOGs) developed gestational weight gain guidelines to minimize the risks associated with obesity during pregnancy. However, a growing body of evidence suggests that current recommendations should be revised for obese women.

OBJECTIVE

 The objective of this study is to assess the impact of gestational weight gain recommendations for obese women (body mass index ≥ 30 kg/m2) on neonatal and maternal outcomes in Quebec.

STUDY DESIGN

 Secondary analysis of the QUARISMA trial was performed including obese women who delivered a full-term singleton in cephalic presentation from 2008 to 2011 in Quebec. Outcomes assessed were composite risks of major neonatal and maternal complications, minor neonatal and maternal complications, as well as obstetrical interventions. Outcomes were compared between weight gain recommendations (reference group) and three weight gain/loss categories using logistic regressions. In second analysis, obese women were stratified by obesity class.

RESULTS

 Among the 16,808 eligible obese women, 605 lost weight during pregnancy, 2,665 gained between 0 and 4.9 kg, 4,355 gained weight within the recommendations (5-9.09 kg), and 9,183 gained at least 9.1 kg. Results showed a significant reduction in major neonatal morbidity (adjusted odds ratio [aOR] = 0.69, 95% confidence interval [CI] = 0.51-0.94), minor maternal morbidity (aOR = 0.79, 95%CI = 0.67-0.93), and assisted vaginal delivery (aOR = 0.82, 95%CI = 0.68-0.99) among women who gained 0 to 4.9 kg compared with the reference group. Cesarean delivery and preeclampsia/eclampsia were significantly reduced with weight loss (aOR = 0.76, 95%CI = 0.64-0.89 and 0.58, 95%CI = 0.42-0.78) compared with the reference group. Weight gain above recommendations was associated with an increased risk of minor neonatal morbidity, major and minor maternal morbidity, as well as cesarean delivery.

CONCLUSION

 Compared with a weight gain within the recommendations, a gestational weight gain/loss of less than 5 kg in obese women is associated with a reduced risk of major neonatal morbidity, minor maternal morbidity, preeclampsia/eclampsia, cesarean delivery, and assisted vaginal delivery. Guidelines on gestational weight gain for obese women should be updated.

KEY POINTS

· Gestational weight gain/loss of less than 5 kg reduces the risk of perinatal complications.. · As suggested by ACOG recommendations, guidelines for obese women should be updated.. · Recommendations stratified by obesity class should be included in revised guidelines..

Validation of Long-term Recall of Pregnancy-related Weight in the Life-course Experiences And Pregnancy Study

BACKGROUND

Prepregnancy body mass index (BMI) and gestational weight gain (GWG) are determinants of maternal and child health. However, many studies of these factors rely on error-prone self-reported measures.

METHODS

Using data from Life-course Experiences And Pregnancy (LEAP), a US-based cohort, we assessed the validity of prepregnancy BMI and GWG recalled on average 8 years postpartum against medical record data treated as alloyed gold standard ("true") values. We calculated probabilities of being classified into a self-reported prepregnancy BMI or GWG category conditional on one's true category (analogous to sensitivities and specificities) and probabilities of truly being in each prepregnancy BMI or GWG category conditional on one's self-reported category (analogous to positive and negative predictive values).

RESULTS

There was a tendency toward under-reporting prepregnancy BMI. Self-report misclassified 32% (95% confidence interval [CI] = 19%, 48%) of those in LEAP with truly overweight and 13% (5%, 27%) with obesity into a lower BMI category. Self-report correctly predicted the truth for 72% (55%, 84%) with self-reported overweight to 100% (90%, 100%) with self-reported obesity. For GWG, both under- and over-reporting were common; self-report misclassified 32% (15%, 55%) with truly low GWG as having moderate GWG and 50% (28%, 72%) with truly high GWG as moderate or low GWG. Self-report correctly predicted the truth for 45% (25%, 67%) with self-reported high GWG to 85% (76%, 91%) with self-reported moderate GWG. Misclassification of BMI and GWG varied across maternal characteristics.

CONCLUSION

Findings can be used in quantitative bias analyses to estimate bias-adjusted associations with prepregnancy BMI and GWG.

Do current pregnancy weight gain guidelines balance risks of adverse maternal and child health in a United States cohort?

BACKGROUND

The Institute of Medicine pregnancy weight gain guidelines were developed without evidence linking high weight gain to maternal cardiometabolic disease and child obesity. The upper limit of current recommendations may be too high for the health of the pregnant individual and child.

OBJECTIVES

The aim of this study was to identify the range of pregnancy weight gain for pregnancies within a normal body mass index (BMI) range that balances the risks of high and low weight gain by simultaneously considering 10 different health conditions.

METHODS

We used data from an United States prospective cohort study of nulliparae followed until 2 to 7 y postpartum (N = 2344 participants with a normal BMI). Pregnancy weight gain z-score was the main exposure. The outcome was a composite consisting of the occurrence of ≥1 of 10 adverse health conditions that were weighted for their seriousness. We used multivariable Poisson regression to relate weight gain z-scores with the weighted composite outcome.

RESULTS

The lowest risk of the composite outcome was at a pregnancy weight gain z-score of -0.6 SD (standard deviation) (equivalent to 13.1 kg at 40 wk). The weight gain ranges associated with no more than 5%, 10%, and 20% increase in risks were -1.0 to -0.2 SD (11.2-15.3 kg), -1.4 to 0 SD (9.4-16.4 kg), and -2.0 to 0.4 SD (7.0-18.9 kg). When we used a lower threshold to define postpartum weight increase in the composite outcome (>5 kg compared with >10 kg), the ranges were 1.6 to -0.7 SD (8.9-12.6 kg), -2.2 to -0.3 SD (6.3-14.7 kg), and ≤0.2 SD (≤17.6 kg). Compared with the ranges of the current weight gain guidelines (-0.9 to -0.1 SD, 11.5-16 kg), the lower limits from our data tended to be lower while upper limits were similar or lower.

CONCLUSIONS

If replicated, our results suggest that policy makers should revisit the recommended pregnancy weight gain range for individuals within a normal BMI range.

Low gestational weight gain (+2.0 to 4.9 kg) for singleton-term gestations associated with favorable perinatal outcomes for all prepregnancy obesity classes

BACKGROUND

Previous studies that evaluated low gestational weight gain or weight loss among prepregnancy obesity classes have not determined the amount of gestational weight gain associated with the lowest risk of adverse perinatal outcomes and neonatal morbidity among singleton term births.

OBJECTIVE

This study aimed to evaluate the relationship of specific gestational weight gain categories of weight loss, stable weight, and low gain considered below the 2009 Institute of Medicine guidelines to perinatal outcomes and neonatal morbidity for singleton, term live births among prepregnancy obesity classes.

STUDY DESIGN

This was a retrospective cohort study of 18,476 women among 3 classes of prepregnancy obesity, based on measured prepregnancy weight, and delivering a live singleton pregnancy at ≥37 weeks of gestation at a Kaiser Permanente Northern California hospital (2009-2012). Variables from electronic medical records included perinatal outcomes, sociodemographics, and measured prepregnancy and delivery weights to calculate total gestational weight gain, used to define 5 gestational weight gain categories: weight loss (<-2.0 kg), stable weight (-2.0 to +1.9 kg), low gain (+2.0 to 4.9 kg), gain within guidelines (+5.0 to 9.1 kg; referent), and gain above guidelines (>9.1 kg). Logistic regression models estimated adjusted odds ratios and 95% confidence intervals of maternal and newborn perinatal outcomes (hypertensive disorders, cesarean delivery, size for gestational age, length of stay, neonatal intensive care unit admission) associated with gestational weight gain categories stratified by prepregnancy obesity classes 1, 2, and 3.

RESULTS

Low gain occurred in 8%, 12%, and 13% of women in obesity class 1 (body mass index, 30.0-34.9), class 2 (body mass index, 35.0-39.9), and class 3 (body mass index, ≥40), respectively. Compared with gestational weight gain within Institute of Medicine guidelines, low gain was associated with similar or improved maternal and newborn perinatal outcomes for all obesity classes without increased odds of neonatal intensive care unit admission, neonatal length of stay ≥3 days, or small for gestational age. The percentages of small for gestational age for the low gain category were 4.4%, 3.0%, and 4.3% among prepregnancy obesity classes 1, 2, and 3, respectively, and comparable with the gestational weight gain within the guideline category (P>.05). The adjusted odds ratios of small-for-gestational age were not statistically significant for all obesity classes; class 1 (1.16; 95% confidence interval, 0.79-1.71) , class 2 (1.05; 95% confidence interval 0.58-1.93), and class 3 (2.03; 95% confidence interval 0.97-4.27).

CONCLUSION

Lower gestational weight gain of +2.0 to 4.9 kg showed the most favorable perinatal outcomes, without higher small for gestational age or neonatal morbidity for all obesity classes.

Novel approaches to examining weight changes in pregnancies affected by obesity

BACKGROUND

Current gestational weight change (GWC) recommendations for obese individuals were established with limited evidence of the pattern and timing of weight change across pregnancy. Similarly, the recommendation of 5-9 kg does not differentiate by the severity of obesity.

OBJECTIVES

We sought to describe GWC trajectory classes by obesity grade and associated infant outcomes among a large, diverse cohort.

METHODS

The study population included 22,355 individuals with singleton pregnancies, obesity (BMI ≥30.0 kg/m2), and normal glucose tolerance who delivered at Kaiser Permanente Northern California between 2008 and 2013. Obesity grade-specific GWC trajectories were modeled at 38 wk using flexible latent class mixed modeling (package lcmm) in R. Multivariable Poisson or linear regression models estimated the associations between the GWC trajectory class and infant outcomes (size-for-gestational age and preterm birth) by obesity grade.

RESULTS

Five GWC trajectory classes were identified for each obesity grade, each with a distinct pattern of weight change before 15 wk (including loss, stability, and gain) followed by weight gain thereafter (low, moderate, and high). Two classes with high overall gain were associated with an increased risk for large for gestational age (LGA) in obesity grade 1 (IRR = 1.27; 95% CI: 1.10, 1.46; IRR = 1.47; 95% CI: 1.24, 1.74). Both high (IRR = 2.02; 95% CI: 1.61, 2.52; IRR = 1.98; 95% CI: 1.52, 2.58) and 2 moderate-gain classes (IRR = 1.40; 95% CI 1.14, 1.71; IRR = 1.51; 95% CI: 1.20, 1.90) were associated with LGA in grade 2, and only early loss/late moderate-gain class 3 (IRR = 1.30; 95% CI: 1.04, 1.62) was associated in grade 3. This class was also associated with preterm birth in grade 2. No associations were detected between GWC and small for gestational age (SGA).

CONCLUSIONS

Among the pregnancies affected by obesity, GWC was not linear or uniform. Different patterns of high gain were associated with an increased risk for LGA with the greatest magnitude in obesity grade 2, whereas GWC patterns were not associated with SGA.

Weight gain patterns among pregnancies with obesity and small- and large-for-gestational-age births

OBJECTIVE

This case-cohort study estimated associations between gestational weight gain (GWG) and small-for-gestational-age (SGA) and large-for-gestational-age (LGA) births stratified by obesity class (I: 30-34.9 kg/m2 ; II: 35-39.9 kg/m2 ; III: ≥40 kg/m2 ) (Magee-Womens Hospital, Pittsburgh, Pennsylvania, 1998-2011).

METHODS

First-trimester GWG was categorized as being below (<0.2 kg), within (0.2-2.0 kg), or above (>2.0 kg) the Institute of Medicine recommendations. For second- and third-trimester GWG, four linear trajectories were derived: approximating maintenance (slope -0.05 ± 0.03 kg/wk), approximating the recommendations (0.27 ± 0.01 kg/wk; reference), higher than the recommendations (0.54 ± 0.01 kg/wk), and highest among those above the recommendations (0.91 ± 0.02 kg/wk).

RESULTS

For classes I, II, and III, respectively, there were 1290, 1247, and 1198 pregnancies in the subcohort; 262, 171, and 123 SGA cases; and 353, 286, and 257 LGA cases. First-trimester GWG was not associated with SGA/LGA births. Second- and third-trimester weight maintenance was associated with potentially lower LGA risk (risk ratio [RR]: 0.80; 95% confidence interval [CI]: 0.55-1.1) but not higher SGA risk (RR: 0.98; 95% CI: 0.64-1.5) for class III. In addition, some sensitivity analyses supported no increased SGA risk with second- and third-trimester weight maintenance for classes I and II.

CONCLUSIONS

Second- and third-trimester weight maintenance may be associated with more optimal birth weight for gestational age. However, how this could be achieved (e.g., through diet and exercise interventions) is unclear, given the observational design of our study.

Are Detailed Behavioral, Psychosocial, and Environmental Variables Necessary to Control for Confounding in Pregnancy Weight Gain Research?

BACKGROUND

Associations between pregnancy weight gain and adverse outcomes may be spurious owing to confounding by factors not typically measured in cohort studies. We determined the extent to which the addition of detailed behavioral, psychosocial, and environmental measurements to commonly available covariates improved control of confounding.

METHODS

We used data from a prospective US pregnancy cohort study (2010-2013, n = 8978). We calculated two propensity scores for low and high pregnancy weight gain (vs. adequate gain) using 11 standard confounders (e.g., age and education). We examined the balance of characteristics between weight gain groups before and after propensity score matching. We used negative binomial regression to estimate the association between weight gain and small- and large-for-gestational-age birth, preterm birth, and unplanned cesarean delivery, controlling for propensity score. To this model, we then added 17 detailed behavioral, psychosocial, and environmental measurements ("fully adjusted"). We calculated the risk ratio owing to confounding as the ratio of the standard confounder-adjusted risk ratio to the fully adjusted risk ratio.

RESULTS

There were minimal imbalances between weight gain groups in detailed measures after matching for a propensity score of standard covariates. Accordingly, the inclusion of detailed covariates had minimal impact on estimated associations between low or high pregnancy weight gain and adverse pregnancy outcomes: risk ratios owing to confounding were null for all outcomes (e.g., 1.1 [95% CI = 1.0, 1.1] for low weight gain and preterm birth).

CONCLUSIONS

Adjustment for detailed behavioral, psychosocial, and environmental measurements had minimal impact on estimated associations between pregnancy weight gain and adverse perinatal outcomes.

Optimal Gestational Weight Gain for Women With Obesity

OBJECTIVE

To determine the optimal gestational weight gain interval for women with obesity in order to minimize neonatal and maternal adverse events.

METHODS

Secondary analysis of the QUARISMA trial, including women with obesity who delivered a full-term singleton in cephalic presentation from 2008 to 2011 in Québec. The primary outcome was a composite risk of major neonatal morbidity. Secondary outcomes were composite risks of major maternal morbidity, minor neonatal and maternal morbidity, and cesarean delivery. Various ranges of weight gain were compared with the current recommendations (reference group) using logistic regression to identify an optimal gestational weight gain interval. In a secondary analysis, women with obesity were stratified by obesity class (I-III).

RESULTS

Among 16 808 eligible women with obesity, 3270 gained less weight than recommended, 4355 gained weight as recommended (5-9.09 kg), and 9183 gained more weight than recommended. Optimal gestational weight change for all women with obesity was -1 to +4 kg and was associated with reduced risk of major neonatal morbidity (aOR 0.49; 95%CI 0.33-0.73, P < 0.001) compared with the reference group. Analysis by class of obesity showed a reduced risk of major neonatal morbidity with a weight change of -1 to +4 kg for class I, -2 to +2 for class II), and -2 to +3 kg for class III.

CONCLUSION

Compared with the current guidelines, a gestational weight change of -1 to +4 kg is associated with reduced risk of adverse perinatal outcomes. While similar findings were seen among women with class I obesity, women with class II or III obesity could benefit from a lower weight gain.

Gestational Weight Gain and Adverse Maternal and Neonatal Outcomes for Pregnancies Complicated by Pregestational and Gestational Diabetes

OBJECTIVE

This study aimed to investigate the association between excess and less than recommended gestational weight gain (GWG) and adverse maternal and neonatal outcomes in women with pregestational and gestational diabetes.

STUDY DESIGN

We conducted a secondary analysis of the National Institute of Child Health and Human Development (NICHD) Consortium on Safe Labor (CSL) study. We included deliveries >23 weeks of nonanomalous singletons with either pregestational or gestational diabetes. The exposure was GWG greater than or less than compared with the U.S. Institute of Medicine recommendations for total pregnancy weight gain per prepregnancy body mass index. Consistent with the 2020 Delphi outcome for diabetes in pregnancy, maternal outcomes included cesarean delivery and preeclampsia and neonatal outcomes included small for gestational age (SGA), large for gestational age (LGA), macrosomia >4,000 g, preterm birth <37 weeks, stillbirth, and neonatal death. We modeled both absolute GWG and GWG z-scores, standardized for gestational duration. Multivariable logistic regression with generalized estimating equations was used, adjusting for age, race/ethnicity, parity, prior cesarean delivery, chronic hypertension, tobacco use, U.S. region, and delivery year.

RESULTS

Of 8,322 deliveries (n = 8,087 women) complicated by pregestational or gestational diabetes, 47% were in excess, 27% were within, and 26% were less than GWG recommendations. Deliveries with excess absolute GWG were at higher adjusted odds of cesarean delivery, preeclampsia, LGA, and macrosomia, compared with those within recommendations. Similar results were observed when using standardized GWG z-scores, in addition to higher likelihood of preterm birth and neonatal death. Less than recommended GWG was associated with a lower likelihood of these adverse outcomes but higher SGA. Additionally, less GWG by z-score was associated with a lower likelihood of stillbirth.

CONCLUSION

Excess GWG increases the risk of adverse maternal and neonatal outcomes for women with pregestational and gestational diabetes. Less GWG than recommended may decrease this risk.

KEY POINTS

· Understanding the impact of GWG modeled using both absolute and standardized measures is needed.. · Among pregnant women with diabetes, excess GWG was common and increased the risk of adverse outcomes and less than recommended GWG may decrease the risk of adverse outcomes, including stillbirth.. · Current recommendations may require revision for women with diabetes in pregnancy..

The importance of nutrition in pregnancy and lactation: lifelong consequences

Most women in the United States do not meet the recommendations for healthful nutrition and weight before and during pregnancy. Women and providers often ask what a healthy diet for a pregnant woman should look like. The message should be “eat better, not more.” This can be achieved by basing diet on a variety of nutrient-dense, whole foods, including fruits, vegetables, legumes, whole grains, healthy fats with omega-3 fatty acids that include nuts and seeds, and fish, in place of poorer quality highly processed foods. Such a diet embodies nutritional density and is less likely to be accompanied by excessive energy intake than the standard American diet consisting of increased intakes of processed foods, fatty red meat, and sweetened foods and beverages. Women who report “prudent” or “health-conscious” eating patterns before and/or during pregnancy may have fewer pregnancy complications and adverse child health outcomes. Comprehensive nutritional supplementation (multiple micronutrients plus balanced protein energy) among women with inadequate nutrition has been associated with improved birth outcomes, including decreased rates of low birthweight. A diet that severely restricts any macronutrient class should be avoided, specifically the ketogenic diet that lacks carbohydrates, the Paleo diet because of dairy restriction, and any diet characterized by excess saturated fats. User-friendly tools to facilitate a quick evaluation of dietary patterns with clear guidance on how to address dietary inadequacies and embedded support from trained healthcare providers are urgently needed.

Recent evidence has shown that although excessive gestational weight gain predicts adverse perinatal outcomes among women with normal weight, the degree of prepregnancy obesity predicts adverse perinatal outcomes to a greater degree than gestational weight gain among women with obesity. Furthermore, low body mass index and insufficient gestational weight gain are associated with poor perinatal outcomes. Observational data have shown that first-trimester gain is the strongest predictor of adverse outcomes. Interventions beginning in early pregnancy or preconception are needed to prevent downstream complications for mothers and their children. For neonates, human milk provides personalized nutrition and is associated with short- and long-term health benefits for infants and mothers. Eating a healthy diet is a way for lactating mothers to support optimal health for themselves and their infants.

Maternal characteristics associated with gestational weight gain in France: a population-based, nationally representative study

OBJECTIVES

To provide nationally representative estimates of gestational weight gain (GWG) and identify maternal characteristics associated with inadequate GWG in France.

DESIGN

A population-based study using data from the French National Perinatal Survey: 2010 and 2016.

SETTING

All maternity units in metropolitan, mainland France (n=535 in 2010; n=493 in 2016).

PARTICIPANTS

Singleton live births with GWG data (N=24 850).

PRIMARY OUTCOME MEASURES

GWG was calculated as end of pregnancy minus pre-pregnancy weight (kg) and categorised as 'insufficient', 'adequate', or 'excessive' using 2009 Institute of Medicine thresholds. Classification accounted for pre-pregnancy body mass index (BMI) (kg/m²; underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), obese (≥30)) and gestational age at birth. We estimated average GWG and the percentage of women in each GWG category. Polytomous logistic regression identified characteristics associated with GWG adequacy.

RESULTS

Average GWG was 13.0 kg (SD 5.6), with 26.8% of women gaining insufficiently, 37.0% adequately and 36.1% excessively. Among other factors, insufficient GWG was associated with underweight (vs normal weight; adjusted OR (aOR) 1.4, 95% CI 1.2 to 1.5) and obese (aOR 1.5, 95% CI 1.4 to 1.7) BMI. Excessive GWG was associated with overweight (aOR 2.8, 95% CI 2.6 to 3.1) and obese BMI (aOR 3.3, 95% CI 2.9 to 3.6). Examining obesity classes separately, odds of insufficient GWG increased from obesity class I to III, while odds of excessive GWG decreased from obesity class I to III. Primiparity (insufficient: aOR 0.9, 95% CI 0.9 to 1.0; excessive: aOR 1.2, 95% CI 1.2 to 1.3), maternal characteristics indicative of lower socioeconomic status, and continuing or quitting smoking during pregnancy were also associated with inadequate GWG.

CONCLUSIONS

In France, insufficient and excessive GWG are common. For optimal outcomes, clinician education, with special attention to the needs of higher risk/vulnerable groups, is needed to ensure all women receive appropriate advice for recommended GWG.

A systematic review of quantitative bias analysis applied to epidemiological research

BACKGROUND

Quantitative bias analysis (QBA) measures study errors in terms of direction, magnitude and uncertainty. This systematic review aimed to describe how QBA has been applied in epidemiological research in 2006-19.

METHODS

We searched PubMed for English peer-reviewed studies applying QBA to real-data applications. We also included studies citing selected sources or which were identified in a previous QBA review in pharmacoepidemiology. For each study, we extracted the rationale, methodology, bias-adjusted results and interpretation and assessed factors associated with reproducibility.

RESULTS

Of the 238 studies, the majority were embedded within papers whose main inferences were drawn from conventional approaches as secondary (sensitivity) analyses to quantity-specific biases (52%) or to assess the extent of bias required to shift the point estimate to the null (25%); 10% were standalone papers. The most common approach was probabilistic (57%). Misclassification was modelled in 57%, uncontrolled confounder(s) in 40% and selection bias in 17%. Most did not consider multiple biases or correlations between errors. When specified, bias parameters came from the literature (48%) more often than internal validation studies (29%). The majority (60%) of analyses resulted in >10% change from the conventional point estimate; however, most investigators (63%) did not alter their original interpretation. Degree of reproducibility related to inclusion of code, formulas, sensitivity analyses and supplementary materials, as well as the QBA rationale.

CONCLUSIONS

QBA applications were rare though increased over time. Future investigators should reference good practices and include details to promote transparency and to serve as a reference for other researchers.

Different methods for assessing gestational weight gain and its association with birth weight

OBJECTIVE

To analyze association of different methods of gestational weight gain assessment with live births small for gestational age (SGA) and large for gestational age (LGA).

METHODS

This was a cross-sectional study with adult women, normal prepregnancy BMI, single pregnancy and gestational age at delivery ≥28 weeks, from the "Birth in Brazil" study, between 2011 and 2012.

RESULTS

Among the 11,000 women participating in the study, prevalence of excessive weight gain was 33.1% according to the Brandão et al. and Institute of Medicine (IOM) methods, and 37.9% according to the Intergrowth method. The chance of being born SGA in the case of insufficient weight gain was OR=1.52 (95%CI 1.06;2.19), OR=1.52 (95%CI 1.05;2.20) and OR=1.56 (95%CI 1.06;2.30) for the Brandão et al., IOM and Intergrowth methods, respectively. Likelihood of excessive weight gain using the same methods was OR=1.53 (95%CI 1.28;1.82), OR=1.57 (95%CI 1.31;1.87) and OR=1.65 (95%CI 1.40;1.96), for LGA respectively.

CONCLUSION

Compared to the IOM recommendations, the Intergrowth and Brandão et al. methods show themselves to be alternatives for identifying SGA and LGA.

Pregnancy weight gain in twin gestations and maternal and child health outcomes at 5 years

Objective:

Current guidelines for maternal weight gain in twin pregnancy were established in the absence of evidence on its longer-term consequences for maternal and child health. We evaluated the association between weight gain in twin pregnancies and the risk of excess maternal postpartum weight increase, childhood obesity, and child cognitive ability.

Methods:

We used 5-year follow-up data from 1000 twins born to 450 mothers in the Early Childhood Longitudinal Study – Birth Cohort, a nationally representative U.S. cohort of births in 2001. Pregnancy weight gain was standardized into gestational age- and prepregnancy body mass index (BMI)-specific z-scores. Excess postpartum weight increase was defined as ≥10 kg increase from prepregnancy weight. We defined child overweight/obesity as BMI ≥ 85^th percentile, and low reading and math achievement as scores one standard deviation below the mean. We used survey-weighted multivariable modified Poisson models with a log link to relate gestational weight gain z-score with each outcome.

Results:

Excess postpartum weight increase occurred in 40% of mothers. Approximately 28% of twins were affected by overweight/obesity, and 16% and 14% had low reading and low math scores. There was a positive linear relationship between pregnancy weight gain and both excess postpartum weight increase and childhood overweight/obesity. Compared with a gestational weight gain z-score 0 SD (equivalent to 20 kg at 37 weeks gestation), a weight gain z-score of +1 SD (27 kg) was associated with 6.3 (0.71, 12) cases of excess weight increase per 1000 women and 4.5 (0.81, 8.2) excess cases of child overweight/obesity per 100 twins. Gestational weight gain was not related to kindergarten academic readiness.

Conclusions:

The high prevalence of excess postpartum weight increase and childhood overweight/obesity within the recommended ranges of gestational weight gain for twin pregnancies suggests that these guidelines could be inadvertently contributing to longer-term maternal and child obesity.

The impact of setting a pregnancy weight gain goal on total weight gain

BACKGROUND

Expert groups recommend that women set a pregnancy weight gain goal with their care provider to optimise weight gain.

OBJECTIVE

Our aim was to describe the concordance between first-trimester personal and provider pregnancy weight gain goals with the Institute of Medicine (IOM) recommendations and to determine the association between these goals and total weight gain.

METHODS

We used data from 9353 women in the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be. In the first trimester, women reported their personal pregnancy weight gain goal and their provider weight gain goal, and we categorised personal and provider weight gain goals and total weight gain according to IOM recommendations. We used log-binomial or linear regression models to relate goals to total weight gain, adjusting for confounders including race/ethnicity, maternal age, education, smoking, marital status and planned pregnancy.

RESULTS

Approximately 37% of women reported no weight gain goals, while 24% had personal and provider goals, 31% had only a personal goal, and 8% had only a provider goal. Personal and provider goals were outside the recommended ranges in 12%-23% of normal-weight women, 31%-41% of overweight women and 47%-63% of women with obesity. Women with both personal and provider pregnancy weight gain goals were 6%-14% more likely than their counterparts to have a goal within IOM-recommended ranges. Having any goal or a goal within the IOM-recommended ranges was unrelated to pregnancy weight gain. Excessive weight gain occurred in approximately half of normal-weight or obese women and three-quarters of overweight women, regardless of goal setting group.

CONCLUSIONS

These findings do not support the effectiveness of early-pregnancy personal or provider gestational weight gain goal setting alone in optimising weight gain. Multifaceted interventions that address a number of mediators of goal setting success may assist women in achieving weight gain consistent with their goals.

Gestational weight gain and delivery outcomes: A population-based cohort study

BACKGROUND

Gestational weight gain is a modifiable factor that could impact maternal and infant health. However, its effect on delivery outcomes is not well established.

OBJECTIVES

To investigate the associations between gestational weight gain and delivery outcomes stratified by early-pregnancy body mass index (BMI).

METHODS

The study population included singleton livebirths in the Stockholm-Gotland obstetric cohort (January 2008 to October 2014; n = 174 953). The exposure was total gestational weight gain standardised into gestational-age-specific z-scores by using previously defined Swedish pregnancy weight gain-for-gestational age charts. The outcomes included caesarean delivery (overall, elective, and emergency), instrumental vaginal delivery, induction of labour, and postpartum haemorrhage. Confounders included maternal age, maternal height, parity, smoking status, cohabitation status, chronic hypertension, and pre-pregnancy diabetes. Logistic regression models with marginal standardisation were used to estimate risk ratios (RR) with 95% confidence intervals (CI) for each delivery outcome stratified by early-pregnancy BMI.

RESULTS

Above average weight gain (z-score ≥ 0.50 SD) increased risks of caesarean delivery (from RR 1.08, 95% CI 1.00, 1.15 to RR 1.45, 95% CI 1.35, 1.55 across BMI groups), induction of labour (from RR 1.14, 95% CI 1.04, 1.23 to RR 1.38, 95% CI 1.25, 1.51 across BMI groups except underweight), and postpartum haemorrhage (from RR 1.13, 95% CI 1.07, 1.19 to RR 1.25, 95% CI 1.09, 1.41 among normal and overweight). Below average weight gain (z-score <-0.50 SD) decreased caesarean delivery risk (from RR 0.77, 95% CI 0.61, 0.93 to RR 0.89, 95% CI 0.84, 0.95 across BMI groups except underweight).

CONCLUSIONS

In normal and overweight women, the risks of caesarean delivery, induction of labour, and postpartum haemorrhage increased with gestational weight gain. In obese women, higher gestational weight gain increased risks of caesarean delivery and induction of labour. Low gestational weight gain reduced risk of caesarean delivery in all BMI groups except underweight.

Nutrition and Metabolic Adaptations in Physiological and Complicated Pregnancy: Focus on Obesity and Gestational Diabetes

Pregnancy offers a window of opportunity to program the future health of both mothers and offspring. During gestation, women experience a series of physical and metabolic modifications and adaptations, which aim to protect the fetus development and are closely related to both pre-gestational nutritional status and gestational weight gain. Moreover, pre-gestational obesity represents a challenge of treatment, and nowadays there are new evidence as regard its management, especially the adequate weight gain. Recent evidence has highlighted the determinant role of nutritional status and maternal diet on both pregnancy outcomes and long-term risk of chronic diseases, through a transgenerational flow, conceptualized by the Development Origin of Health and Diseases (Dohad) theory. In this review we will analyse the physiological and endocrine adaptation in pregnancy, and the metabolic complications, thus the focal points for nutritional and therapeutic strategies that we must early implement, virtually before conception, to safeguard the health of both mother and progeny. We will summarize the current nutritional recommendations and the use of nutraceuticals in pregnancy, with a focus on the management of pregnancy complicated by obesity and hyperglycemia, assessing the most recent evidence about the effects of ante-natal nutrition on the long-term, on either maternal health or metabolic risk of the offspring.

Exploration of the Vaginal and Gut Microbiome in African American Women by Body Mass Index, Class of Obesity, and Gestational Weight Gain: A Pilot Study

OBJECTIVE

This study determines the differences in the distal gut and vaginal microbiome in African American (AA) women by prepregnancy body mass index and gestational weight gain (GWG) comparing women with and without obesity and by obesity class.

STUDY DESIGN

We prospectively sampled the vaginal and distal gut microbiome in pregnant AA women at two time points during pregnancy. Samples were analyzed using high-throughput sequencing of the V4 region of the 16S ribosomal ribonucleic acid gene.

RESULTS

Distinct differences in vaginal and distal gut α-diversity were observed at time point 1 between women with and without obesity by total GWG. Significant differences in distal gut β-diversity were also found at time point 1 in obese women by GWG. Within the Bacteroides genus, a significant association was observed by total GWG among obese women which was absent in nonobese women. Women with class III obesity who experienced low GWG had the lowest abundance of distal gut Bacteroides and appreciably higher relative abundance of a consortia of vaginal taxa including Atopobium, Gardnerella, Prevotella, and Sneathia.

CONCLUSION

These results contribute new evidence showing that GWG in combination with obesity and obesity class is associated with an altered distal gut and vaginal composition early in pregnancy among AA women.

Weight gain during pregnancy and the risk of severe maternal morbidity by prepregnancy BMI

BACKGROUND

High and low prepregnancy BMI are risk factors for severe maternal morbidity (SMM), but the contribution of gestational weight gain (GWG) is not well understood.

OBJECTIVES

We evaluated associations between GWG and SMM by prepregnancy BMI group.

METHODS

We analyzed administrative records from 2,483,684 Californian births (2007-2012), utilizing z score charts to standardize GWG for gestational duration. We fit the z scores nonlinearly and categorized GWG as above, within, or below the Institute of Medicine (IOM) recommendations after predicting equivalent GWG at term from the z score charts. SMM was defined using a validated index. Associations were estimated using multivariable logistic regression models.

RESULTS

We found generally shallow U-shaped relations between GWG z score and SMM in all BMI groups, except class 3 obesity (≥40 kg/m2), for which risk was lowest with weight loss. The weight gain amount associated with the lowest risk of SMM was within the IOM recommendations for underweight and class 2 obesity, but above the IOM recommendations for normal weight, overweight, and class 1 obesity. The adjusted risk ratios (RRs) and 95% CIs for GWG below the IOM recommendations, compared with GWG within the recommendations, were the following for underweight, normal weight, overweight, class 1 obesity, class 2 obesity, and class 3 obesity: 1.13 (0.99, 1.29), 1.09 (1.04, 1.14), 1.10 (1.01, 1.19), 1.07 (0.95, 1.21), 1.03 (0.88, 1.22), and 0.89 (0.73, 1.08), respectively. For GWG above the recommendations, the corresponding RRs and 95% CIs were 0.99 (0.84, 1.15), 1.04 (0.99, 1.08), 0.98 (0.92, 1.04), 1.03 (0.95, 1.13), 1.07 (0.94, 1.23), and 1.08 (0.91, 1.30), respectively.

CONCLUSIONS

High and low GWG may be modestly associated with increased risk of SMM across BMI groups, except in women with class 3 obesity, for whom low weight gain and weight loss may be associated with decreased risk of SMM.

Body Composition During Pregnancy Differs by Obesity Class

OBJECTIVE

The aim of this study is to characterize changes in body composition during pregnancy in women with obesity.

METHODS

Fifty-four healthy women with obesity (class 1, 30-34.9 kg/m² : n = 25; class 2, 35-39.9 kg/m² : n = 21; class 3, ≥ 40.0 kg/m² : n = 8) expecting a singleton pregnancy were studied. Body composition was measured in early pregnancy (13-16 weeks), midpregnancy (24-27 weeks), and late pregnancy (35-37 weeks) using air displacement plethysmography, stable isotopes, and skinfold thickness measurements. Fasting glucose, insulin, and leptin were measured.

RESULTS

The gain in fat-free mass was lower in the second trimester compared with the third (2.7 ± 0.2 to 5.3 ± 0.2 kg; P < 0.001), whereas fat mass accumulation declined over time (0.6 ± 0.3 to -0.7 ± 0.4 kg; P = 0.005). Women with class 1 and 2 obesity gained 1.1 ± 0.7 kg of fat mass during pregnancy, while women with class 3 obesity lost 4.1 ± 0.6 kg (both P < 0.001). The difference in fat accumulation between obesity classes was observed only in the second trimester (P = 0.02). Gestational weight gain was associated positively with changes in plasma concentrations of insulin, leptin, and insulin resistance (all P < 0.01).

CONCLUSIONS

Gestational weight gain in pregnancy differs by obesity class and trimester. Women with class 3 obesity gain less body weight and fat mass. Fat mass gain is most likely preventable in the second trimester.

Association between gestational weight gain and severe adverse birth outcomes in Washington State, US: A population-based retrospective cohort study, 2004-2013

BACKGROUND

Suboptimal weight gain during pregnancy is a potentially modifiable risk factor. We aimed to investigate the association between suboptimal gestational weight gain and severe adverse birth outcomes by pre-pregnancy body mass index (BMI) categories, including obesity class I to III.

METHODS AND FINDINGS

We conducted a population-based study of pregnant women with singleton hospital births in Washington State, US, between 2004 and 2013. Optimal, low, and excess weight gain in each BMI category was calculated based on weight gain by gestational age as recommended by the American College of Obstetricians and Gynecologists and the Institute of Medicine. Primary composite outcomes were (1) maternal death and/or severe maternal morbidity (SMM) and (2) perinatal death and/or severe neonatal morbidity. Logistic regression was used to obtain adjusted odds ratios (AORs) and 95% confidence intervals. Overall, 722,839 women with information on pre-pregnancy BMI were included. Of these, 3.1% of women were underweight, 48.1% had normal pre-pregnancy BMI, 25.8% were overweight, and 23.0% were obese. Only 31.5% of women achieved optimal gestational weight gain. Women who had low weight gain were more likely to be African American and have Medicaid health insurance, while women with excess weight gain were more likely to be non-Hispanic white and younger than women with optimal weight gain in each pre-pregnancy BMI category. Compared with women who had optimal weight gain, those with low gestational weight gain had a higher rate of maternal death, 7.97 versus 2.63 per 100,000 (p = 0.027). In addition, low weight gain was associated with the composite adverse maternal outcome (death/SMM) in women with normal pre-pregnancy BMI and in overweight women (AOR 1.12, 95% CI 1.04-1.21, p = 0.004, and AOR 1.17, 95% CI 1.04-1.32, p = 0.009, respectively) compared to women in the same pre-pregnancy BMI category who had optimal weight gain. Similarly, excess gestational weight gain was associated with increased rates of death/SMM among women with normal pre-pregnancy BMI (AOR 1.20, 95% CI 1.12-1.28, p < 0.001) and obese women (AOR 1.12, 95% CI 1.01-1.23, p = 0.019). Low gestational weight gain was associated with perinatal death and severe neonatal morbidity regardless of pre-pregnancy BMI, including obesity classes I, II, and III, while excess weight gain was associated with severe neonatal morbidity only in women who were underweight or had normal BMI prior to pregnancy. Study limitations include the ascertainment of pre-pregnancy BMI using self-report, and lack of data availability for the most recent years.

CONCLUSIONS

In this study, we found that most women do not achieve optimal weight gain during pregnancy. Low weight gain was associated with increased risk of severe adverse birth outcomes, and in particular with maternal death and perinatal death. Excess gestational weight gain was associated with severe adverse birth outcomes, except for women who were overweight prior to pregnancy. Weight gain recommendations for this group may need to be reassessed. It is important to counsel women during pregnancy about specific risks associated with both low and excess weight gain.

Gestational Weight Gain and Adverse Birth Outcomes in Twin Pregnancies

OBJECTIVE

To evaluate the association between gestational weight gain in twin pregnancies and small-for-gestational-age (SGA) and large-for-gestational-age (LGA) birth, preterm birth before 32 weeks of gestation, cesarean delivery, and infant death within each prepregnancy body mass index (BMI) category.

METHODS

Data in this population-based study came from Pennsylvania-linked infant birth and death records (2003-2013). We studied 54,836 twins born alive before 39 weeks of gestation. Total pregnancy weight gain (kg) was converted to gestational age-standardized z scores. Multivariable modified Poisson regression models stratified by prepregnancy BMI were used to estimate associations between z scores and outcomes. A probabilistic bias analysis, informed by an internal validation study, evaluated the effect of BMI and weight gain misclassification.

RESULTS

Gestational weight gain z score was negatively associated with SGA and positively associated with LGA and cesarean delivery in all BMI groups. The relation between weight gain and preterm birth was U-shaped in nonobese women. An increased risk of infant death was observed for very low weight gain among normal-weight women and for high weight gain among women without obesity. Most excess risks of these outcomes were observed at weight gains at 37 weeks of gestation that are equivalent to less than 14 kg or more than 27 kg in underweight or normal-weight women, less than 11 kg or more than 28 kg in overweight women, and less than 6.4 kg or more than 26 kg in women with obesity. The bias analysis supported the validity of the conventional analysis.

CONCLUSION

Very low or very high weight gains were associated with the adverse outcomes we studied. If the associations we observed are even partially reflective of causality, targeted modification of pregnancy weight gain in women carrying twins might improve pregnancy outcomes.

Gestational Weight Gain Particularly Affects the Risk of Large for Gestational Age Infants in Non-obese Mothers

Introduction The birth of a large for gestational age (LGA) infant is a significant risk factor for birth complications and maternal morbidity and an even higher risk factor for offspring obesity, metabolic syndrome and cardiovascular disease in later life. Relevant factors affecting the risk of delivering an LGA infant are maternal pre-gravid obesity, excessive gestational weight gain exceeding the recommendations of the Institute of Medicine (IOM) and diabetes in pregnancy. We aimed to determine what matters most in terms of the risk of fetal overgrowth.

Materials and Methods We performed a database analysis of 12 701 singleton term deliveries documented in our university hospital birth registry from 2003 to 2014. Multivariate logistic regression analysis was used to determine the adjusted odds ratios.

Results Excessive weight gain had the strongest impact on LGA (OR: 1.249 [95% CI: 1.018 – 1.533]) compared to maternal pre-gravid body mass index (BMI) (OR: 1.083 [95% CI: 1.066 – 1.099]) and diabetes (OR: 1.315 [95% CI: 0.997 – 1.734]). Keeping gestational weight gain within the recommendations of the IOM resulted in a risk reduction for LGA of 20% (OR: 0.801 [95% CI: 0.652 – 0.982]). The risk for LGA increases by 6.9% with each kg weight gain. Normal weight women (BMI 18.5 – 24.9 kg/m ² ) and moderately overweight women (BMI 25 – 29.9 kg/m ² ) showed the highest increase in LGA rates per kg weight gain during pregnancy (OR: 1.078 [95% CI: 1.052 – 1.104] and OR: 1.058 [95% CI: 1.026 – 1.09], resp.). Only in underweight (< 18.5 kg/m ² ) and normal weight women the risk of LGA birth is strongly influenced by diabetes (OR 11.818 [95% CI: 1.156–120.782] and 1.564 [95% CI: 1.013–2.415]).

Conclusion Excessive weight gain is particularly important for non-obese women. These women are therefore a target cohort for intervention, as each prevented additional kilogram weight gain reduces the risk of LGA by more than 5%.

Energy Intake Requirements in Pregnancy

Energy intake requirements in pregnancy match the demands of resting metabolism, physical activity, and tissue growth. Energy balance in pregnancy is, therefore, defined as energy intake equal to energy expenditure plus energy storage. A detailed understanding of these components and their changes throughout gestation can inform energy intake recommendations for minimizing the risk of poor pregnancy outcomes. Energy expenditure is the sum of resting and physical activity-related expenditure. Resting metabolic rate increases during pregnancy as a result of increased body mass, pregnancy-associated physiological changes, i.e., cardiac output, and the growing fetus. Physical activity is extremely variable between women and may change over the course of pregnancy. The requirement for energy storage depends on maternal pregravid body size. For optimal pregnancy outcomes, women with low body weight require more fat mass accumulation than women with obesity, who do not require to accumulate fat mass at all. Given the high energy density of fat mass, these differences affect energy intake requirements for a healthy pregnancy greatly. In contrast, the energy stored in fetal and placental tissues is comparable between all women and have small impact on energy requirements. Different prediction equations have been developed to quantify energy intake requirements and we provide a brief review of the strengths and weaknesses and discuss their application for healthy management of weight gain in pregnant women.

Evidence-based recommendations for energy intake in pregnant women with obesity

BACKGROUND

In women with obesity, excess gestational weight gain (≥270 g/week) occurs in two out of three pregnancies and contributes to metabolic impairments in both mother and baby. To improve obstetrical care, objectively assessed information on energy balance is urgently needed. The objective of this study was to characterize determinants of gestational weight gain in women with obesity.

METHODS

This was a prospective, observational study of pregnant women with obesity. The primary outcome was energy intake calculated by the energy intake-balance method. Energy expenditure was measured by doubly-labeled water and whole-room indirect calorimetry and body composition as 3-compartment model by air displacement plethysmography and isotope dilution in early (13-16 weeks) and late pregnancy (35-37 weeks).

RESULTS

In pregnant women with obesity (n=54), recommended weight gain (n=8, 15%) during the second and third trimesters was achieved when energy intake was 125±52 kcal/d less than energy expenditure. In contrast, women with excess weight gain (67%) consumed 186±29 kcal/d more than they expended (P<0.001). Energy balance affected maternal adiposity (recommended: -2.5±0.8 kg fat mass, excess: +2.2±0.5, inadequate: -4.5±0.5, P<0.001), but not fetal growth. Weight gain was not related to demographics, activity, metabolic biomarkers, or diet quality. We estimated that energy intake requirements for recommended weight gain during the second and third trimesters were not increased as compared to energy requirements early in pregnancy (34±53 kcal/d, P=0.83).

CONCLUSIONS

We here provide the first evidence-based recommendations for energy intake in pregnant women with obesity. Contrary to current recommendations, energy intake should not exceed energy expenditure.

FUNDING

This study was funded by the National Institutes of Health (R01DK099175; Redman, U54GM104940 and P30DK072476; Core support).

TRIAL REGISTRATION

clinicaltrials.gov: NCT01954342.

Measurement error is often neglected in medical literature: a systematic review

OBJECTIVES

In medical research, covariates (e.g., exposure and confounder variables) are often measured with error. While it is well accepted that this introduces bias and imprecision in exposure-outcome relations, it is unclear to what extent such issues are currently considered in research practice. The objective was to study common practices regarding covariate measurement error via a systematic review of general medicine and epidemiology literature.

STUDY DESIGN AND SETTING

Original research published in 2016 in 12 high impact journals was full-text searched for phrases relating to measurement error. Reporting of measurement error and methods to investigate or correct for it were quantified and characterized.

RESULTS

Two hundred and forty-seven (44%) of the 565 original research publications reported on the presence of measurement error. 83% of these 247 did so with respect to the exposure and/or confounder variables. Only 18 publications (7% of 247) used methods to investigate or correct for measurement error.

CONCLUSIONS

Consequently, it is difficult for readers to judge the robustness of presented results to the existence of measurement error in the majority of publications in high impact journals. Our systematic review highlights the need for increased awareness about the possible impact of covariate measurement error. Additionally, guidance on the use of measurement error correction methods is necessary.

Pharmacoepidemiology in Pharmacogenetics

Epidemiologic methods provide rigorous means by which to study the interplay between genetic factors and drug response. In this chapter, we describe the differences between experimental and observational study designs, and illustrate how to implement the highly efficient case-control study design. We discuss analytic approaches to evaluating gene-drug interactions within typical study designs and review sources of bias that must be assessed and accounted for in epidemiologic analyses.

Obstetric and perinatal outcomes in subfertile patients who conceived following low technology interventions for fertility enhancement: a comprehensive review

PURPOSE

Low technology interventions for fertility enhancement (LTIFE) are strategies that avoid retrieval, handling, and manipulation of female gametes. The definition of LTIFE is yet to be widely accepted and clarified, but they are commonly used in milder cases of infertility and subfertility. Based on these considerations, the aim of the present study was comprehensively to review and investigate the obstetric and perinatal outcomes in subfertile patients who underwent LTIFE.

METHODS

A literature search up to May 2017 was performed in IBSS, SocINDEX, Institute for Scientific Information, PubMed, Web of Science, and Google Scholar. An evidence-based hierarchy was used according to The Oxford Centre for Evidence-Based Medicine to determine which articles to include and analyze, and to provide a level of evidence of each association between intervention and outcome.

RESULTS

This analysis identified preliminary and low-grade evidence on the influence of LTIFE on obstetric and perinatal outcomes in subfertile women.

CONCLUSIONS

LTIFE women should deserve major consideration from Clinicians/Researchers of Reproductive Medicine, because these treatments could be potentially responsible for mothers' and babies' complications. So far, the lack of well-designed and unbiased studies makes further conclusions difficult to be drawn.

Composite neonatal and maternal morbidities with small- versus appropriate- for gestational age among uncomplicated obese women undergoing repeat cesarean delivery. J Matern Fetal Neonatal Med 2017;32:562-567. [PMID: 28942717 DOI: 10.1080/14767058.2017.1384808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

PURPOSE

Our goal was to compare composite neonatal and maternal morbidities (composite neonatal morbidity (CNM), composite maternal morbidity (CMM)) among deliveries with small for age (SGA) versus appropriate for gestational age (AGA; birthweight 10-89%) among obese versus non-obese women undergoing repeat cesarean delivery (CD).

STUDY DESIGN

This is a secondary analysis of a prospective observational study. Women who had elective CD ≥37 weeks were studied. We excluded multiple gestations, fetal anomalies, > 1 prior CD, and medical diseases. Patients were divided into BMI ≥30 versus <30 kg/m². CNM included respiratory distress syndrome, necrotizing enterocolitis, severe intraventricular hemorrhage, seizure, or death; CMM included transfusion, hysterectomy, operative injury, coagulopathy, thromboembolism, pulmonary edema, or death. Multivariate logistic regression was used to control for confounding factors.

RESULTS

Of 7561 women, we included 65% were obese and 35% were not. SGA rates differed significantly: 8 versus 12% (p < .001). Overall, CNM was significantly higher in patients with SGA versus AGA (adjusted odds ratio (aOR) 2.04, 95% CI 1.19-3.49). CMM of SGA in obese versus non-obese was statistically different (aOR 0.11, 95% CI 0.02-0.68). Among obese mothers, SGA neonates had significantly higher CNM compared with AGA ones (aOR 2.17, 95% CI 1.03-4.59).

CONCLUSIONS

SGA occurred in 8% of low-risk obese women with prior CD. CNM of SGA babies in obese versus non-obese women were similar. Paradoxically, CMM was lower in obese cases, possibly reflecting the caution that obese patients receive preoperatively. Our findings may assist in counseling patients and designing trials.

Influence of pre-pregnancy leisure time physical activity on gestational and postpartum weight gain and birth weight - a cohort study

In order to examine the association between pre-pregnancy leisure time physical activities and gestational weight gain, postpartum weight gain and birth weight, we analysed prospectively collected data from 1827 women with singleton term pregnancies. Women were categorised in groups of sedentary women, light exercisers, moderate exercisers and competitive athletes. The results showed that sedentary women on average gained 14.1 kg during pregnancy, whereas light exercisers gained 13.7 kg, moderate exercisers gained 14.3 kg and competitive athletes 16.1 kg. Competitive athletes had an increased risk of having a gestational weight gain above Institute of Medicine (IOM) recommendations with an odds ratio of 2.60 (1.32-5.15) compared to light exercisers. However, birth weight and one year postpartum weight was similar for all four groups. Thus, although competitive athletes gain more weight than recommended during pregnancy, this may not affect birth weight or postpartum weight. Impact statement What is already known on this subjectPrevious studies have found that increased pre-pregnancy physical activity is associated with lower gestational weight gain during the last trimester, but showed no association between the pre-pregnancy level of physical activity and mean birth weight. What the results of this study addWe found that women classified as competitive exercisers had a 2.6-fold increased risk of gaining more weight than recommended compared to light exercisers. Nearly 6 out of 10 women among the competitive exercisers gained more weight than recommended by IOM. Surprisingly, this did not appear to increase birth weight or post-partum weight gain, but other adverse effects cannot be excluded. What the implications are of these findings for clinical practice and/or further researchIn the clinical practice it may be relevant to focus on and advise pre-pregnancy competitive exercisers in order to prevent excessive gestational weight gain.

Weight gain during pregnancy and the black-white disparity in preterm birth

PURPOSE

To quantify the relationship between pregnancy weight gain with early and late preterm birth and evaluate whether associations differed between non-Hispanic (NH) black and NH white women.

METHODS

We analyzed a retrospective cohort of all live births to NH black and NH white women in the United States 2011-2015 (n = 10,714,983). We used weight gain z-scores in multiple logistic regression models stratified by prepregnancy body mass index (BMI) and race to calculate population attributable risk (PAR) percentages for the contribution of high and low pregnancy weight gain to early and late preterm birth.

RESULTS

Pregnancy weight gain was related to early and late preterm birth, but associations varied by BMI and race. For early preterm birth, the PAR percentage for high pregnancy weight gain ranged from 8 to 10% in NH black women and from 6 to 8% in NH white women. There was little evidence of racial differences in late preterm birth: PAR percentages ranged from 2 to 7% in NH black women and from 3 to 7% in NH white women.

CONCLUSIONS

Moderate gestational weight gain is associated with lower rate of preterm birth, with greatest reductions for early preterm birth in NH black women.