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..

Prenatal Weight Change Trajectories and Perinatal Outcomes among Twin Gestations.

OBJECTIVE: Despite an increase in twin pregnancies in recent decades, the Institute of Medicine twin weight gain recommendations remain provisional and provide no guidance for the pattern or timing of weight change. We sought to characterize gestational weight change trajectory patterns and examine associations with birth outcomes in a cohort of twin pregnancies. STUDY DESIGN: Prenatal and delivery records were examined for 320 twin pregnancies from a maternal-fetal medicine practice in Austin, TX 2011-2019. Prenatal weights for those with >1 measured weight in the first trimester and ≥3 prenatal weights were included in analyses. Trajectories were estimated to 32 weeks (mean delivery: 33.7 ± 3.3 weeks) using flexible latent class mixed models with low-rank thin-plate splines. Associations between trajectory classes and infant outcomes were analyzed using multivariable Poisson or linear regression. RESULTS: Weight change from prepregnancy to delivery was 15.4 ± 6.3 kg for people with an underweight body mass index, 15.4 ± 5.8 kg for healthy weight, 14.7 ± 6.9 kg for overweight, and 12.5 ± 6.4 kg for obesity. Three trajectory classes were identified: low (Class 1), moderate (Class 2), or high gain (Class 3). Class 1 (24.7%) maintained weight for 15 weeks and then gained an estimated 6.6 kg at 32 weeks. Class 2 (60.9%) exhibited steady gain with 13.5 kg predicted total gain, and Class 3 (14.4%) showed rapid gain across pregnancy with 21.3 kg predicted gain. Compared to Class 1, Class 3 was associated with higher birth weight z-score (ß = 0.63, 95% confidence interval [CI]: 0.31,0.96), increased risk for large for gestational age (IRR = 5.60, 95% CI: 1.59, 19.67), and birth <32 weeks (IRR = 2.44, 95%CI: 1.10, 5.4) that was attenuated in sensitivity analyses. Class 2 was associated with moderately elevated birth weight z-score (ß = 0.24, 95%CI: 0.00, 0.48, p = 0.050). CONCLUSION: Gestational weight change followed a low, moderate, or high trajectory; both moderate and high gain patterns were associated with increased infant size outcomes. Optimal patterns of weight change that balance risk during the prenatal, perinatal, and neonatal periods require further investigation, particularly in high-risk twin pregnancies. KEY POINTS: · A majority gained weight below IOM twin recommendations.. · Three patterns of GWC across pregnancy were identified.. · Moderate or high GWC was associated with infant size..

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.

Body Composition Trajectories During the First 23 Months of Life Differ by HIV Exposure Among Infants in Western Kenya: A Prospective Study.

BACKGROUND: Infants who are HIV-exposed and uninfected have suboptimal growth patterns compared to those who are HIV-unexposed and uninfected. However, little is known about how these patterns persist beyond 1 year of life. OBJECTIVES: This study aimed to examine whether infant body composition and growth trajectories differed by HIV exposure during the first 2 years of life among Kenyan infants using advanced growth modeling. METHODS: Repeated infant body composition and growth measurements (mean: 6; range: 2-7) were obtained from 6 weeks to 23 months in the Pith Moromo cohort in Western Kenya (n = 295, 50% HIV-exposed and uninfected, 50% male). Body composition trajectory groups were fitted using latent class mixed modeling (LCMM) and associations between HIV exposure and growth trajectories were examined using logistic regression analysis. RESULTS: All infants exhibited poor growth. However, HIV-exposed infants generally grew suboptimally than unexposed infants. Across all body composition models except for the sum of skinfolds, HIV-exposed infants had a higher likelihood of belonging to the suboptimal growth groups identified by LCMM than the HIV-unexposed infants. Notably, HIV-exposed infants were 3.3 times more likely (95% CI: 1.5-7.4) to belong to the length-for-age z-score growth class that remained at a z-score of < -2, indicating stunted growth. HIV-exposed infants were also 2.6 times more likely (95% CI: 1.2-5.4) to belong to the weight-for-length-for-age z-score growth class that remained between 0 and -1, and were 4.2 times more likely (95% CI: 1.9-9.3) to belong to the weight-for-age z-score growth class that indicated poor weight gain besides stunted linear growth. CONCLUSIONS: In a cohort of Kenyan infants, HIV-exposed infants grew suboptimally compared to HIV-unexposed infants beyond 1 year of age. These growth patterns and longer-term effects should be further investigated to support the ongoing efforts to reduce early-life HIV exposure-related health disparities.

Breastfeeding, socioeconomic status, and long-term postpartum weight retention.

BACKGROUND: Almost half of all pregnant women in the United States gain weight above Institute of Medicine gestational weight gain guidelines. Breastfeeding has been shown to reduce weight retention in the first year postpartum; however, women with lower socioeconomic status (SES) tend to initiate breastfeeding less often than women with higher SES. We investigated associations between duration of breastfeeding with mother's long-term postpartum weight status at 4-10 years and evaluated whether the associations varied by SES. METHODS: Maternal and infant dyads (N = 2144 dyads) are from the Geographic Research on Wellbeing survey (GROW), 2012-2013, a long-term, cross-sectional follow-up of the Maternal and Infant Health Assessment (MIHA) based in California, USA. Pre-pregnancy body mass index (BMI) was obtained from self-report of height and weight during MIHA, while breastfeeding history and self-report of current body weight was collected at the 4-10 year GROW postpartum visit. SES score was derived from a composite score of percent federal poverty level and education and was dichotomized into High and Low SES groups at a score of three. Multivariable linear regression was used to examine association between breastfeeding and maternal weight status, and to examine for effect modification by SES. RESULTS: Average long-term weight retention 4-10 years postpartum was 4.0 kg. Fewer lower SES vs. higher SES women breast fed at least six months (51% versus 70%, p < .001) or ever breastfed (74% versus 89%, P < .001). Women who breastfed at least six months had lower long-term postpartum weight retention compared to those who did not (b = -1.06 kg, (-1.93, 0.25); p = 0.01); however, these association did not vary by SES. CONCLUSION: Six months of breastfeeding is associated with lower BMI at 4-10 years and lower body weight, and effects do not vary by SES. Future policies and guidelines should consider building an infrastructure that is supportive of longer breastfeeding duration. Moreover, further research is needed to identify the impact of additional behavioral and environmental factors on long-term maternal weight status. Understanding the drivers of excessive weight retention pospartum can help us not only improve the pregnant person's health but the health of their children.