Association of Gestational Weight Gain With Infant Morbidity and Mortality in the United States

Influence of Food Security Status and Diet Quality on Maternal Gestational Weight Gain

BACKGROUND

Recommended gestational weight gain (GWG) is crucial for health of women and their offspring. Food security status is hypothesized to influence diet quality and GWG. Therefore, we examined the relationship between diet quality and GWG by food security status.

METHODS

Participants (n = 679) were enrolled in the Initial Vanguard Study of the National Children's Study. GWG was calculated as third trimester weight minus prepregnancy weight. Food security status and diet quality (Healthy Eating Index [HEI]-2015) were assessed using the Household Food Security Survey and a Diet History Questionnaire, respectively. General linear models evaluated the relationship between GWG and HEI-2015 by food security status.

RESULTS

A greater proportion of women experienced food security (81.3%) compared with food insecurity (18.7%). In women with food security, GWG was negatively associated with HEI-2015 in women having overweight (r = -0.421, P = .003) and positively associated with HEI-2015 in women with inadequate GWG (r = 0.224, P = .019). Conversely, no significant relationships were found between GWG and HEI-2015 in women with food insecurity.

DISCUSSION

Improved diet quality potentially lowers GWG in women with food security. However, in vulnerable populations, including women with food insecurity, improvements in diet quality may not effectively enhance GWG.

Gestational Weight Gain Among Urban and Rural Pregnant Individuals Who Smoke or Quit Smoking

INTRODUCTION

Approximately 7.2% of individuals in the U.S. smoke during pregnancy, and cessation is associated with excessive gestational weight gain (GWG). Weight gain is a common reason for not quitting smoking or relapsing. The current study aimed to characterize who is at risk for excessive GWG and determine the moderating effect of rurality given the higher smoking rates and lower access to healthcare services in these areas.

METHODS

Data from the Virginia Pregnancy Risk Assessment Monitoring System (PRAMS; years 2009-2020) were used to assess the association between participant characteristics, smoking behaviors, and rurality by excessive GWG status in 2023.

RESULTS

Almost half (44.0%) of participants experienced excessive GWG; 9.8% of participants quit smoking while 6.9% continued smoking. Respondents who quit during pregnancy had higher odds of excessive GWG than non-smoking respondents (OR=1.83, 95% CI: [1.24, 2.71]). Among those who were non-smoking, respondents in rural areas, compared to urban areas, had a higher probability of experiencing excessive GWG (0.46 vs 0.44, p<0.001). For those who quit smoking (0.60 vs 0.41, p<0.001) or continued to smoke during pregnancy (0.46 vs 0.33, p<0.001), urban residence was associated with a higher likelihood of excessive GWG compared to rural residence.

CONCLUSIONS

Smoking cessation and weight management during pregnancy are critical to promoting infant and maternal health. Targeted interventions combining weight management and smoking cessation have been successful among the general population and could be adapted for pregnant individuals who smoke to facilitate cessation and healthy GWG in both urban and rural areas.

The impact of gestational weight gain on fetal and neonatal outcomes: the Araraquara Cohort Study

BACKGROUND

Gestational weight gain (GWG) is an important indicator for monitoring maternal and fetal health.

OBJECTIVE

To evaluate the effect of GWG outside the recommendations of the Institute of Medicine (IOM) on fetal and neonatal outcomes.

STUDY DESIGN

A prospective cohort study with 1642 pregnant women selected from 2017 to 2023, with gestational age ≤ 18 weeks and followed until delivery in the city of Araraquara, Southeast Brazil. The relationship between IOM-recommended GWG and fetal outcomes (abdominal subcutaneous tissue thickness, arm and thigh subcutaneous tissue area and intrauterine growth restriction) and neonatal outcomes (percentage of fat mass, fat-free mass, birth weight and length, ponderal index, weight adequateness for gestational age by the Intergrowth curve, prematurity, and Apgar score) were investigated. Generalized Estimating Equations were used.

RESULTS

GWG below the IOM recommendations was associated with increased risks of intrauterine growth restriction (IUGR) (aOR 1.61; 95% CI: 1.14-2.27), low birth weight (aOR 2.44; 95% CI: 1.85-3.21), and prematurity (aOR 2.35; 95% CI: 1.81-3.05), and lower chance of being Large for Gestational Age (LGA) (aOR 0.38; 95% CI: 0.28-0.54), with smaller arm subcutaneous tissue area (AST) (-7.99 g; 95% CI: -8.97 to -7.02), birth length (-0.76 cm; 95% CI: -1.03 to -0.49), and neonatal fat mass percentage (-0.85%; 95% CI: -1.12 to -0.58). Conversely, exceeding GWG guidelines increased the likelihood of LGA (aOR 1.53; 95% CI: 1.20-1.96), with lower 5th-minute Apgar score (aOR 0.42; 95% CI: 0.20-0.87), and increased birth weight (90.14 g; 95% CI: 53.30 to 126.99).

CONCLUSION

Adherence to GWG recommendations is crucial, with deviations negatively impacting fetal health. Effective weight control strategies are imperative.

Pre-pregnancy BMI, rate of gestational weight gain, and preterm birth among US Pacific Islander individuals

OBJECTIVE

The objective of this study was to examine the association between rate of gestational weight gain (GWG) and preterm birth (PTB) classified by pre-pregnancy BMI among Pacific Islander individuals in the United States.

METHODS

Pacific Islander mothers (n = 55,975) and singleton infants (22-41 gestational weeks) without congenital anomalies were included using data from the National Center for Health Statistics (2014-2018). PTB was compared by pre-pregnancy BMI among women in each stratum of rate of GWG using Cox proportional hazards models.

RESULTS

Compared with mothers with a rate of GWG within the guidelines, mothers with a rate of GWG below the guidelines and either pre-pregnancy underweight (adjusted hazard ratio [aHR] = 1.84, 95% CI: 1.10-3.06), healthy weight (aHR = 1.38, 95% CI: 1.15-1.65), obesity class I (aHR = 1.22, 95% CI: 0.97-1.52), or obesity class II (aHR = 1.43, 95% CI: 1.05-1.96) had an increased risk of PTB; mothers with a rate of GWG above the guidelines and either pre-pregnancy underweight (aHR = 1.57, 95% CI: 0.92-2.69) or obesity class II (aHR = 1.31, 95% CI: 0.98-1.76) had an increased risk of PTB.

CONCLUSIONS

The association between rate of GWG below or above the guidelines and PTB differs by pre-pregnancy BMI among Pacific Islander individuals.

Association of COVID-19 pandemic societal closures with gestational weight gain among women in South Carolina, 2018-2021

PURPOSE

During the early COVID-19 pandemic, an increase in weight gain among the general population was observed; however, gestational weight gain (GWG) was not thoroughly evaluated. We evaluated changes in GWG during the pandemic closures in South Carolina.

METHODS

We used live, singleton birth records to compare GWG outcomes among three pregnancy groups occurring before (January 2018-February 2020), during (March-May 2020), and after (June 2020-December 2021) pandemic closures. GWG categories were defined by the Institute of Medicine (IOM) recommendations. We used multinomial logistic regression models to calculate prevalence ratios (PRs) of GWG categories stratified by prepregnancy body mass index (BMI) category.

RESULTS

We analyzed 177,571 birth records. Women with normal weight (n = 64,491, 36%) had a slightly lower prevalence of excessive GWG during and after the pandemic closures (PR 0.94; 95% CI: 0.91-0.98 and PR 0.95; 95% CI: 0.93-0.98, respectively). We observed no changes in GWG patterns for women with overweight and obesity.

CONCLUSIONS

We found limited changes in GWG patterns for a subset of pregnant women during and after pandemic closures, compared with prepandemic period in South Carolina, countering findings of weight changes among the general population.

Weight Loss, Stability, and Low Weight Gain during Pregnancy among Individuals with Obesity: Associations with Adverse Perinatal Outcomes: An Observational Study

OBJECTIVE

 The safety of weight loss and low weight gain during pregnancy remains unclear. To determine how different patterns of gestational weight gain (GWG), including weight loss, stability, and low GWG relate to perinatal outcomes by prepregnancy obesity class.

STUDY DESIGN

 The study population included 29,408 singleton livebirths among pregnant people with obesity from Kaiser Permanente Northern California (2008-2013). Clinically measured GWG was grouped into meaningful categories (Adequate: reference, met 2009 National Academy of Medicine [NAM] Guidelines [5-9.1 kg], Excessive [>9.1 kg], Low [1-4.9 kg], Stable [±1 kg], Weight Loss [>1 kg]) or GWG Z-score quintiles. Modified Poisson regression was used to estimate risk of adverse outcomes, stratified by obesity class. Electronic health record data were used to define outcomes, including cesarean delivery, preterm birth, admission to the neonatal intensive care unit, small- and large-for-gestational age infants.

RESULTS

 Prevalence of weight stability and weight loss was 3.8 and 3.4%, respectively. Compared with those who gained within NAM, increased risk of small-for-gestational age was observed among those with weight loss among obesity class I (Risk Ratio (RR): 1.57, 95% confidence interval [CI]: 1.12, 2.19), obesity class II (RR: 2.18, 95% CI: 1.52, 3.13), and obesity class III (RR: 1.72, 95% CI: 1.21, 2.45). Weight loss was associated with a decreased risk of cesarean delivery among obesity class III, compared with NAM.

CONCLUSION

 Weight loss during pregnancy is associated with increased risk of small-for-gestational age among all obesity classes, but not other adverse perinatal outcomes and may reduce risk of cesarean delivery. Low weight gain and weight stability are not associated with risk of adverse outcomes among those with class III obesity. GWG guidelines may need to vary by obesity class.

KEY POINTS

· Weight loss during pregnancy is associated with increased risk of small-for-gestational age among all obesity classes; but weight loss was not associated with other adverse perinatal outcomes.. · Among class III, low weight gain and weight stability are not associated with adverse perinatal outcomes.. · GWG guidelines may need to vary by obesity class..

Association between inadequate weight gain according to the institute of medicine 2009 guidelines and pregnancy outcomes in women with thyroid disorders

PURPOSE

Gestational weight gain (GWG) is an important contributor to pregnancy outcomes in the general obstetric population and different subgroups. The corresponding information in women with thyroid conditions is limited. We aimed to evaluate the relationship between GWG according to institute of medicine (IOM) and pregnancy outcomes in women with thyroid disorders.

METHODS

We performed a retrospective analysis of 620 pregnant women either treated with levothyroxine (N = 545) or attended because of hyperthyroidism during pregnancy (N = 75).

RESULTS

The associations between GWG according to IOM and pregnancy outcomes were present both in women treated with thyroid hormone and women followed by hyperthyroidism, most of them related to the fetal outcomes. In women treated with levothyroxine, insufficient GWG was associated with gestational diabetes mellitus (GDM) (odds ratio (OR) 2.32, 95% confidence interval (CI) 1.18, 4.54), preterm birth (OR 2.31, 95% CI 1.22, 4.36), small-for-gestational age newborns (OR 2.38, 95% CI 1.09, 5.22) and respiratory distress (OR 6.89, 95% CI 1.46, 32.52). Excessive GWG was associated with cesarean delivery (OR 1.66, 95% CI 1.10, 2.51) and macrosomia (OR 2.75, 95% CI 1.38, 5.49). Large-for-gestational age newborns were associated with both insufficient GWG (OR 0.25, 95% CI 0.11, 0.58) and excessive GWG (OR 1.80, 95% CI 1.11, 2.92). In women followed by hyperthyroidism, excessive GWG was associated with large-for-gestational age newborns (OR 5.56, 95% CI 1.03, 29.96).

CONCLUSION

GWG according to IOM is associated with pregnancy outcomes both in women treated with thyroid hormone and women followed by hyperthyroidism.

Sub-optimal maternal gestational gain is associated with shorter leukocyte telomere length at birth in a predominantly Latinx cohort of newborns

OBJECTIVE

To assess in utero exposures associated with leukocyte telomere length (LTL) at birth and maternal LTL in a primarily Latinx birth cohort.

STUDY DESIGN

Mothers and newborns were recruited postnatally before 24 h of life. Newborn LTL was collected via heelstick at birth and maternal LTL was collected postnatally. LTL was determined by quantitative PCR. Using a longitudinal design, we evaluated associations between neonatal and maternal LTL and appropriate maternal gestational gain as indicated by the American College of Obstetrics and Gynecology (ACOG).

RESULT

Mean infant LTL was 2.02 ± 0.30 T/S (n = 386) and maternal LTL was 1.54 ± 0.26 T/S (n = 58). Independent risk factors for shorter LTL at birth included longer gestational duration (Coeff:-0.03, 95%CI: -0.05-0.01;p < 0.01) and maternal gestational weight gain below ACOG recommendations (Coeff:-0.10, 95%CI: -0.18 - -0.02; p = 0.01).

CONCLUSION

Gestational weight gain below ACOG recommendations may adversely impact neonatal health in Latinx infants as indicated by shorter LTL at birth.

Gestational weight gain among pregnant women in Ibadan, Nigeria: Pattern, predictors and pregnancy outcomes

BACKGROUND

Gestational weight gain (GWG) is a risk factor for adverse pregnancy outcomes, future obesity and chronic diseases among women. However, has not received much attention in many low and middle-income countries such as Nigeria. We investigated the pattern, associated factors and pregnancy outcomes of GWG in Ibadan, Nigeria, using the Ibadan Pregnancy Cohort Study (IbPCS).

METHODOLOGY

The IbPCS is a multicentre prospective cohort study conducted among 1745 pregnant women recruited from four health facilities in Ibadan, Nigeria. GWG, the primary outcome, was categorised according to the Institute of Medicine's classification into insufficient, adequate and excessive weight gain. Pregnancy outcomes were the secondary outcome variables. Logistic regression analysis (Adjusted odds ratios and 95% confidence interval CI) was used to examine associations, and Poisson regression analyses were used to investigate associations with outcomes.

RESULTS

Only 16.9% of women had optimal GWG, 56.8% had excessive GWG, and 26.9% had insufficient GWG. Excessive GWG was associated with high income '> #20,000-' (AOR: 1.64, 95% CI: 1.25-2.17), being overweight (AOR: 2.12, 95% CI: 1.52-2.95) and obese (AOR: 1.47, 95% CI: 1.02-2.13) after adjusting for confounders. In contrast, increased odds of insufficient GWG have associated women with depression (AOR: 1.70, 95% CI 1.17-2.47). There was no significant association between inappropriate GWG and pregnancy outcomes However, there was an increased odds for postpartum haemorrhage (AOR: 2.44, 95% CI 1.14-5.22) among women with obesity and excessive GWG.

CONCLUSIONS

Excessive GWG was the most typical form of GWG among our study participants and was associated with high maternal income, and being overweight or obese. GWG needs to be monitored during antenatal care, and interventions that promote appropriate GWG should be implemented among pregnant women in Nigeria.

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.

Pregnancy as an Early Cardiovascular Moment: Peripartum Cardiovascular Health

Pregnancy is commonly referred to as a window into future CVH (cardiovascular health). During pregnancy, physiological adaptations occur to promote the optimal growth and development of the fetus. However, in approximately 20% of pregnant individuals, these perturbations result in cardiovascular and metabolic complications, which include hypertensive disorders of pregnancy, gestational diabetes, preterm birth, and small-for-gestational age infant. The biological processes that lead to adverse pregnancy outcomes begin before pregnancy with higher risk of adverse pregnancy outcomes observed among those with poor prepregnancy CVH. Individuals who experience adverse pregnancy outcomes are also at higher risk of subsequent development of cardiovascular disease, which is largely explained by the interim development of traditional risk factors, such as hypertension and diabetes. Therefore, the peripartum period, which includes the period before (prepregnancy), during, and after pregnancy (postpartum), represents an early cardiovascular moment or window of opportunity when CVH should be measured, monitored, and modified (if needed). However, it remains unclear whether adverse pregnancy outcomes reflect latent risk for cardiovascular disease that is unmasked in pregnancy or if adverse pregnancy outcomes are themselves an independent and causal risk factor for future cardiovascular disease. Understanding the pathophysiologic mechanisms and pathways linking prepregnancy CVH, adverse pregnancy outcomes, and cardiovascular disease are necessary to develop strategies tailored for each stage in the peripartum period. Emerging evidence suggests the utility of subclinical cardiovascular disease screening with biomarkers (eg, natriuretic peptides) or imaging (eg, computed tomography for coronary artery calcium or echocardiography for adverse cardiac remodeling) to identify risk-enriched postpartum populations and target for more intensive strategies with health behavior interventions or pharmacological treatments. However, evidence-based guidelines focused on adults with a history of adverse pregnancy outcomes are needed to prioritize the prevention of cardiovascular disease during the reproductive years and beyond.

Maternal and Neonatal Outcomes of Pregnancy within 7 years after Roux-Y Gastric Bypass or Sleeve Gastrectomy Surgery

PURPOSE

Few studies examine whether maternal and neonatal outcomes differ by time from metabolic and bariatric surgery (MBS) to conception. We describe maternal and neonatal outcomes among women with pregnancy after Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) overall and by whether conception occurred during the period when pregnancy is not recommended (< 18 months postoperative) versus later.

MATERIALS AND METHODS

A prospective cohort study enrolled 135 US adult women (median age, 30 years, body mass index [BMI], 47.2 kg/m2) who underwent RYGB or SG (2006-2009) and subsequently reported ≥ 1 pregnancy within 7 years. Participants self-reported pregnancy-related information annually. Differences in prevalence of maternal and neonatal outcomes by postoperative conception timeframe (< 18 versus ≥ 18 months) were assessed.

RESULTS

Thirty-one women reported ≥ 2 postoperative pregnancies. At time of postoperative conception (median 26 [IQR:22-52] months postoperative) median BMI was 31 (IQR:27-36) kg/m2. Excessive gestational weight gain (55%), cesarean section (42%) and preterm labor or rupture of membranes (40%) were the most common maternal outcomes. Forty percent of neonates had a composite outcome of still birth (1%), preterm birth (26%), small for gestational age (11%), or neonatal intensive care unit admission (8%). Prevalence of outcomes did not statistically significantly differ by timeframe.

CONCLUSION

In US women who conceived ≤ 7 years following RYGB or SG, 40% of neonates had the composite neonatal outcome. The prevalence of maternal and neonatal outcomes post-MBS were not statistically significant by conception timeframe.

Gestational weight gain and pregnancy outcomes in women with type 1 and type 2 diabetes mellitus

AIMS

We aimed to explore the relationship between gestational weight gain (GWG) after Institute of Medicine (IOM) and pregnancy outcomes in women with type 1 and type 2 diabetes.

METHODS

Retrospective cohort study at a tertiary medical center (1981-2011).

OUTCOME VARIABLES

2 maternal and 14 fetal. Main exposure variable: GWG according to IOM. We calculated crude and adjusted ORs as well as population attributable (PAF) and preventable fractions (PPF) for significant positive and negative associations, respectively.

RESULTS

We evaluated 633 pregnant women with type 1 or type 2 diabetes. GWG was insufficient (iGWG) in 16.7% and excessive (eGWG) in 50.7%. In the adjusted analysis, GWG according to IOM was significantly associated with maternal outcomes (pregnancy-induced hypertension and cesarean delivery) and four fetal outcomes (large-for-gestational age, macrosomia, small-for-gestational age and neonatal respiratory distress). The association with large-for-gestational age newborns was negative for iGWG (0.48, CI 95% 0.25-0.94) and positive for eGWG (1.76, CI 95% 1.18-2.63). In addition, iGWG was associated with a higher risk of small-for-gestational age newborns and respiratory distress and eGWG with a higher risk of pregnancy-induced hypertension, caesarean delivery and macrosomia. PAF and PPF ranged from the 20.4% PPF of iGWG for large-for-gestational age to 56.5% PAF of eGWG for macrosomia.

CONCLUSION

In this cohort of women with type 1 or type 2 diabetes, inadequate GWG after IOM was associated with adverse pregnancy outcomes; associations were unfavorable for eGWG and mixed for iGWG. The attributable fractions were not moderate, pointing to the potential impact of modifying inadequate GWG.

The impact of phenylalanine levels during pregnancy on birth weight and later development in children born to women with phenylketonuria

Strict metabolic control with dietary treatment during pregnancy is essential for women with phenylketonuria (PKU), as elevated levels of phenylalanine (Phe) are toxic to the developing fetus. Maternal delay in achievement of the recommended Phe level during pregnancy is associated with delayed development of the child. However, the extent to which risk is changed by later or less stringently performed dietary treatment is unclear. The aim of this study was to investigate the impact of Phe levels and time of initiation of a Phe-restricted diet in pregnant women with PKU on birth weight, head circumference and later development of their children. Birth data were obtained from the medical records of women with PKU giving birth in the period 1980-2020. Later development was investigated by interviewing the mothers about their children's development and health. We included 79 children of 41 women with PKU. The women showed good adherence with the diet and had mean blood Phe levels within target range (248 ± 62 μmol/L). The children's development was not affected by fluctuations in the women's Phe levels, that occurred especially in first trimester. Despite maternal Phe levels being within target range, 19 children (26.8%) had low birth weight below 10th percentile. This study indicates that with dietary treatment, the children are born with the same prospect for normal development and health as children born to non-PKU mothers. This is despite maternal fluctuations in the Phe levels during first trimester.

Optimal gestational weight gain in women with twin pregnancies and gestational diabetes mellitus: a population-based study in the United States

BACKGROUND

There is limited evidence regarding optimal gestational weight gain in women with twin pregnancies and gestational diabetes mellitus.

OBJECTIVE

This study aimed to examine the association between gestational weight gain and perinatal outcomes among women with gestational diabetes mellitus and twin pregnancies and to explore the gestational weight gain targets by prepregnancy body mass index category.

STUDY DESIGN

A national population-based cohort study of twin pregnancies with gestational diabetes mellitus was conducted between 2014 and 2020. Women with gestational diabetes mellitus aged between 18 and 45 years with live-born twins without congenital malformations between 24 and 42 weeks of gestation were included in the analysis. Two approaches were used to determine the optimal gestational weight gain targets by body mass index category: an interquartile range method to calculate targets in low-risk gestational diabetes mellitus pregnancies and a logistic model method to identify the odds ratio targets at which a composite adverse outcome decreased.

RESULTS

Of 29,308 women with gestational diabetes mellitus and twin pregnancies, 8239 (28.1%) were normal-weight, 7626 (26.0%) were overweight, and 13,443 (45.9%) were obese. The continuous standardized gestational weight gain by 36 weeks was associated with preterm birth <36 weeks, large-for-gestational-age infants, small-for-gestational-age infants, and gestational hypertensive disorders. The interquartile range targets were 13.6 to 20.9 kg, 10.9 to 20.4 kg, and 7.7 to 17.7 kg for normal-weight, overweight, and obese women, respectively. The odds ratio targets were 14.1 to 20.0 kg, 12.1 to 16.0 kg, and 6.1 to 12.0 kg for normal-weight, overweight, and obese women, respectively. Gestational weight gain outside these targets was associated with preterm birth <36 weeks, large-for-gestational-age and small-for-gestational-age infants, and gestational hypertensive disorders, and exhibited significant population attributable fractions for preterm birth <36 weeks, large-for-gestational-age infants, and gestational hypertensive disorders across body mass index categories.

CONCLUSION

Compared with the Institute of Medicine guidelines, more stringent gestational weight gain targets would be beneficial for improved perinatal outcomes in women with gestational diabetes mellitus and twin pregnancies.

Association of Optimal Gestational Weight Gain Ranges With Perinatal Outcomes Across Body Mass Index Categories in Twin Pregnancies

IMPORTANCE

The existing gestational weight gain (GWG) recommendations for twin pregnancies are lacking for underweight individuals and are not stratified by obesity class.

OBJECTIVE

To identify optimal GWG ranges associated with reduced adverse perinatal outcomes stratified by prepregnancy body mass index (BMI) categories in twin pregnancies.

DESIGN, SETTING AND PARTICIPANTS

This population-based cohort study of twin pregnancies using data from the National Center for Health Statistics was conducted between January 1, 2014, and December 31, 2018. Statistical analysis was performed from October 24, 2021, to May 7, 2022. The study population comprised 262 604 individuals between 18 and 45 years of age with live-born twins without congenital malformation between 24 and 42 weeks of gestation. Two approaches were used to determine the optimal GWG ranges: a statistics-based approach calculating IQRs of GWG in a low-risk population, and an outcome-based approach identifying GWG thresholds below or above which an adverse perinatal outcome increased.

EXPOSURE

Gestational weight gain.

MAIN OUTCOMES AND MEASURES

Preterm birth less than 36 weeks, gestational hypertensive disorders, small for gestational age status, large for gestational age status, and a composite outcome defined as any occurrence of the individual outcomes.

RESULTS

The main sample comprised 200 810 individuals with twin pregnancies (mean [SD] maternal age, 30.4 [5.5] years; 1624 [0.8%] American Indian or Alaska Native, 13 031 [6.5%] Asian or Pacific Islander, 36 423 [18.1%] Black, and 149 732 [74.6%] White; and 137 409 [68.4%] multiparous). In the low-risk subgroup (n = 61 794), the IQRs of the total GWG after 36 weeks of gestation as assessed using a statistics-based approach and based on BMI group were 15.9 to 22.7 kg for underweight, 15.4 to 22.7 kg for normal weight, 12.7 to 22.2 kg for overweight, 10.0 to 20.0 kg for class 1 obesity, 7.7 to 18.1 kg for class 2 obesity, and 5.9 to 16.3 kg for class 3 obesity. The absolute risk of the composite outcome showed U-shaped associations with GWG across BMI categories. The optimal GWG ranges by 36 weeks identified using an outcome-based approach and BMI group were 17.5 to 24.9 kg for underweight, 15.0 to 24.9 kg for normal weight, 15.0 to 24.9 kg for overweight, 10.0 to 19.9 kg for class 1 obesity, 7.5 to 17.4 kg for class 2 obesity, and 5.0 to 9.9 kg for class 3 obesity. The multivariable logistic models assessed using the validation sample (n = 49 275) showed that GWG defined outside those optimal ranges was associated with preterm birth at less than 36 weeks, gestational hypertensive disorders, and small or large for gestational age.

CONCLUSIONS AND RELEVANCE

This population-based cohort study found that optimal GWG ranges were similar for individuals with underweight and normal weight but decreased with increasing severity of obesity. The current US Institute of Medicine GWG recommendations may be too high for individuals with moderate or severe obesity.