Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.

BACKGROUND: The World Health Organization recommends 1500 to 2000 mg of calcium daily as supplementation, divided into three doses, for pregnant persons in populations with low dietary calcium intake in order to reduce the risk of preeclampsia. The complexity of the dosing scheme, however, has led to implementation barriers. METHODS: We conducted two independent randomized trials of calcium supplementation, in India and Tanzania, to assess the noninferiority of a 500-mg daily dose to a 1500-mg daily dose of calcium supplementation. In each trial, the two primary outcomes were preeclampsia and preterm birth, and the noninferiority margins for the relative risks were 1.54 and 1.16, respectively. RESULTS: A total of 11,000 nulliparous pregnant women were included in each trial. The cumulative incidence of preeclampsia was 3.0% in the 500-mg group and 3.6% in the 1500-mg group in the India trial (relative risk, 0.84; 95% confidence interval [CI], 0.68 to 1.03) and 3.0% and 2.7%, respectively, in the Tanzania trial (relative risk, 1.10; 95% CI, 0.88 to 1.36) - findings consistent with the noninferiority of the lower dose in both trials. The percentage of live births that were preterm was 11.4% in the 500-mg group and 12.8% in the 1500-mg group in the India trial (relative risk, 0.89; 95% CI, 0.80 to 0.98), which was within the noninferiority margin of 1.16; in the Tanzania trial, the respective percentages were 10.4% and 9.7% (relative risk, 1.07; 95% CI, 0.95 to 1.21), which exceeded the noninferiority margin. CONCLUSIONS: In these two trials, low-dose calcium supplementation was noninferior to high-dose calcium supplementation with respect to the risk of preeclampsia. It was noninferior with respect to the risk of preterm live birth in the trial in India but not in the trial in Tanzania. (Funded by the Bill and Melinda Gates Foundation and others; ClinicalTrials.gov number, NCT03350516; Clinical Trials Registry-India number, CTRI/2018/02/012119; and Tanzania Medicines and Medical Devices Authority Trials Registry number, TFDA0018/CTR/0010/5).

Experiences, acceptability and barriers to calcium supplementation during pregnancy in Dar es Salaam, Tanzania.

Calcium supplementation in pregnancy is recommended in contexts with low dietary calcium intake to reduce the risk of pre-eclampsia and its complications. The World Health Organisation suggested high-dose calcium supplementation (1500-2000 mg/day), divided into three doses and taken at different times from daily iron-folic supplements. We conducted a mixed methods evaluation study to assess experiences, acceptability and barriers to high-dose calcium supplementation from the perspectives of pregnant women and antenatal health care providers at two public health facilities in Dar es Salaam, Tanzania. Descriptive statistics and thematic analysis were used to characterise acceptability, barriers and overall experiences of using high-dose calcium supplementation. Pregnant women in the cohort were aged 19-41 years, with 32.4% being primiparous. The proportion of pregnant women who liked calcium supplements 'a lot' decreased from 50.2% at the first visit to 31.8% at the last antenatal follow-up visit. Adherence was 71.3% (interquartile range: 50.5%, 89.3%), with only 24.0% of the participants taking 90% or more of the required supplements. Although participants expressed positive attitudes towards using calcium supplements, they also voiced concerns about the large size, side effects, the potential to forget and the burden of taking calcium supplements three times per day. Antenatal health care providers also affirmed the high burden of taking calcium supplements in addition to iron-folic acid supplements. Participants expressed the acceptability of using calcium supplements during pregnancy, but adherence to three doses per day posed challenges to pregnant women. Reducing the number of calcium supplement doses per day may improve adherence.

Risk factors for inadequate and excessive gestational weight gain in 25 low- and middle-income countries: An individual-level participant meta-analysis.

BACKGROUND: Many women experience suboptimal gestational weight gain (GWG) in low- and middle-income countries (LMICs), but our understanding of risk factors associated with GWG in these settings is limited. We investigated the relationships between demographic, anthropometric, lifestyle, and clinical factors and GWG in prospectively collected data from LMICs. METHODS AND FINDINGS: We conducted an individual participant-level meta-analysis of risk factors for GWG outcomes among 138,286 pregnant women with singleton pregnancies in 55 studies (27 randomized controlled trials and 28 prospective cohorts from 25 LMICs). Data sources were identified through PubMed, Embase, and Web of Science searches for articles published from January 2000 to March 2019. Titles and abstracts of articles identified in all databases were independently screened by 2 team members according to the following eligibility criteria: following inclusion criteria: (1) GWG data collection took place in an LMIC; (2) the study was a prospective cohort or randomized trial; (3) study participants were pregnant; and (4) the study was not conducted exclusively among human immunodeficiency virus (HIV)-infected women or women with other health conditions that could limit the generalizability of the results. The Institute of Medicine (IOM) body mass index (BMI)-specific guidelines were used to determine the adequacy of GWG, which we calculated as the ratio of the total observed weight gain over the mean recommended weight gain. Study outcomes included severely inadequate GWG (percent adequacy of GWG <70), inadequate GWG (percent adequacy of GWG <90, inclusive of severely inadequate), and excessive GWG (percent adequacy of GWG >125). Multivariable estimates from each study were pooled using fixed-effects meta-analysis. Study-specific regression models for each risk factor included all other demographic risk factors measured in a particular study as potential confounders, as well as BMI, maternal height, pre-pregnancy smoking, and chronic hypertension. Risk factors occurring during pregnancy were further adjusted for receipt of study intervention (if any) and 3-month calendar period. The INTERGROWTH-21st standard was used to define high and low GWG among normal weight women in a sensitivity analysis. The prevalence of inadequate GWG was 54%, while the prevalence of excessive weight gain was 22%. In multivariable models, factors that were associated with a higher risk of inadequate GWG included short maternal stature (<145 cm), tobacco smoking, and HIV infection. A mid-upper arm circumference (MUAC) of ≥28.1 cm was associated with the largest increase in risk for excessive GWG (risk ratio (RR) 3.02, 95% confidence interval (CI) [2.86, 3.19]). The estimated pooled difference in absolute risk between those with MUAC of ≥28.1 cm compared to those with a MUAC of 24 to 28.09 cm was 5.8% (95% CI 3.1% to 8.4%). Higher levels of education and age <20 years were also associated with an increased risk of excessive GWG. Results using the INTERGROWTH-21st standard among normal weight women were similar but attenuated compared to the results using the IOM guidelines among normal weight women. Limitations of the study's methodology include differences in the availability of risk factors and potential confounders measured in each individual dataset; not all risk factors or potential confounders of interest were available across datasets and data on potential confounders collected across studies. CONCLUSIONS: Inadequate GWG is a significant public health concern in LMICs. We identified diverse nutritional, behavioral, and clinical risk factors for inadequate GWG, highlighting the need for integrated approaches to optimizing GWG in LMICs. The prevalence of excessive GWG suggests that attention to the emerging burden of excessive GWG in LMICs is also warranted.

Associations Between Social Support and Symptoms of Antenatal Depression with Infant Growth and Development Among Mothers Living with HIV in Tanzania.

Children born to mothers living with HIV may experience greater risk of poor growth and development outcomes than their HIV-unexposed peers. Few studies have examined the relationship between maternal depression and social support with infant growth and development in the context of HIV. We conducted a prospective cohort study of 2,298 pregnant women living with HIV in Dar es Salaam, Tanzania, assessing antenatal depression (Hopkins Symptoms Checklist-25) and social support (Duke-UNC Functional Social Support Questionnaire) at 12-27 weeks of gestation. At one-year age, infant anthropometry and caregiver-reported infant development were assessed. Generalized estimating equations were used to assess mean differences (MD) and relative risks (RR) for growth and developmental outcomes. Symptoms consistent with maternal antenatal depression had 67% prevalence and were associated with infant wasting (RR 2.61; 95% confidence interval (CI) 1.03-6.65; z = 2.02; p = 0.04), but no other growth or developmental outcomes. Greater maternal social support was not associated with infant growth outcomes. Greater affective support was associated with better cognitive (MD 0.18; CI 0.01-0.35; z = 2.14; p = 0.03) and motor (MD 0.16; CI 0.01-0.31; z = 2.04; p = 0.04) development scores. Greater instrumental support was associated with better cognitive (MD 0.26; CI 0.10-0.42; z = 3.15; p < 0.01), motor (MD 0.17; CI 0.02-0.33; z = 2.22; p = 0.03), and overall (MD 0.19; CI 0.03-0.35; z = 2.35; p = 0.02) development scores. Depressive symptoms were associated with greater risk of wasting, while social support was associated with better infant development scores. Strategies to improve mental health and social support for mothers living with HIV during the antenatal period may benefit infant growth and development.

Correlates of internalizing and externalizing problems among school-going young adolescents in Sub-Saharan Africa.

Mental health in adolescence is important for health and well-being throughout the life course, but evidence from Sub-Saharan Africa is sparse. This study aimed to assess the correlates of internalizing, externalizing and cumulative problems among early adolescents. This study used cross-sectional survey data from 3516 school-going adolescents in Ouagadougou, Burkina Faso; Addis Ababa, Ethiopia and Dar es Salaam, Tanzania. We used a 25-item Strengths and Difficulties Questionnaire to measure internalizing, externalizing and cumulative problems. We carried out multi-variable linear regression analyses with the estimation of adjusted mean differences and 95% confidence intervals, to determine the factors associated with internalizing, externalizing and cumulative problems. Overall, 1 in 8 adolescents had internalizing problems, while 1 in 10 had externalizing problems. In two sites, having friends was related to lower internalizing problems, while repeating a grade, physical fights and household food insecurity were related to greater internalizing problems. Household food insecurity and involvement in physical fights were associated with greater externalizing problems across sites, while repeating a grade was linked with greater externalizing problems in two sites. Having a caring adult in school was associated with fewer externalizing problems across sites, while having friends was associated with fewer externalizing problems in two sites. Overall, having friends was related to fewer cumulative problems, while physical fights and household food insecurity were related to higher cumulative problems. School-based mental health and food programs may be useful in addressing social-emotional problems among school-aged adolescents in Burkina Faso, Ethiopia and Tanzania.

Timing of Antiretroviral Therapy: Initiation and Birth Outcomes Among Pregnant Women With Human Immunodeficiency Virus in Tanzania

BACKGROUND: Combination antiretroviral therapy (cART) initiation during pregnancy reduces the risk of perinatal human immunodeficiency virus (HIV) transmission; however, studies have suggested that there may be unintended adverse consequences on birth outcomes for selected cART regimens. METHODS: We analyzed adverse birth outcomes among a prospective cohort of 1307 pregnant women with HIV in Dar es Salaam who initiated cART during the first or second trimester of a singleton pregnancy. Our primary analysis compared birth outcomes by gestational age at cART initiation among these women initiating cART in pregnancy. RESULTS: Among women who initiated cART in pregnancy, there was no relationship of gestational age at cART initiation with the risk of fetal death or stillbirth. However, women who initiated cART before 20 weeks of gestation compared with after 20 weeks had increased risk of preterm birth (risk ratio [RR], 1.30; 95% confidence interval [CI], 1.03-1.67) but decreased risk of small-for-gestational age birth (RR, 0.71; 95% CI, .55-.93). CONCLUSIONS: With increasing use of cART preconception and early in pregnancy, clinicians should be aware of the benefits and potential risks of cART regimens to optimize birth outcomes.

Postnatal Stature Does Not Largely Mediate the Relation between Adverse Birth Outcomes and Cognitive Development in Mid-Childhood and Early Adolescence in Rural Western China.

BACKGROUND: Preterm birth and fetal growth restriction are associated with linear growth faltering and suboptimal cognitive development in childhood. OBJECTIVES: We aimed to investigate whether and to what extent the associations between adverse birth outcomes and cognitive development in mid-childhood and early adolescence are mediated by postnatal stature. METHODS: We used data from a prospective birth cohort of children born to women who participated in a large cluster-randomized trial of antenatal micronutrient supplementation in rural western China. Children were followed up for anthropometric assessments at 6, 12, and 24 mo of age and in mid-childhood (7-9 y). Cognitive development was assessed in mid-childhood (n = 669) and early adolescence (n = 735; 10-12 y) using the Wechsler Intelligence Scale for Children-IV. We conducted a causal mediation analysis to evaluate the proportion of the association of low birth weight (LBW; <2500 g), small-for-gestational age (SGA; <10th percentile), and preterm birth (<37 weeks of gestation) with cognitive development in mid-childhood and early adolescence that was mediated by postnatal length/height-for-age and -sex z score (LAZ/HAZ) during the first 2 y of life and in mid-childhood. RESULTS: LBW and SGA, but not preterm birth, were associated with lower cognitive test scores in mid-childhood and early adolescence. The proportion of the total association of SGA with adolescent cognitive development that was mediated by LAZ/HAZ at 6, 12, and 24 mo of age and in mid-childhood was 25%, 32%, 32%, and 27%, respectively. The corresponding proportions for LBW were 25%, 32%, 16%, and 24%, respectively. CONCLUSIONS: The association of LBW and SGA with cognitive development in mid-childhood and adolescence is not largely mediated by postnatal stature during the first 2 y of life. Postnatal interventions that address the antecedent causes of poor child growth and development, rather than early childhood growth alone, are more likely to mitigate the risk of suboptimal development among SGA and LBW children. This trial was registered at www.isrctn.com as ISRCTN08850194.

Multivitamin Supplementation Is Associated with Greater Adequacy of Gestational Weight Gain among Pregnant Women in Tanzania.

BACKGROUND: Gestational weight gain (GWG) is a modifiable risk factor associated with adverse birth outcomes. Studies have shown that the provision of multiple micronutrient supplements to pregnant women reduces the risk of low birth weight. However, the effect of multiple micronutrient supplements on GWG has been understudied. OBJECTIVES: We examined the effect of daily supplementation of pregnant women with multivitamins on GWG in relation to the GWG recommendation by the Institute of Medicine (IOM). METHODS: Pregnant women with gestational age between 12 and 27 wk were randomly assigned to receive daily multivitamins or placebo until delivery. Weight was measured at enrollment and every follow-up visit. Percentage adequacy of GWG was calculated as actual GWG divided by the recommended GWG according to the IOM recommendation. Binary outcomes included severely inadequate (<70%), inadequate (<90%), and excessive GWG (≥125%). The analysis included 7573 women with singleton pregnancies. Multiple linear regression models were used to examine the association between multivitamin supplementation and percentage adequacy of GWG, and log-binomial models were used for binary outcomes. RESULTS: The mean percentage adequacy of GWG was 96.7% in the multivitamin arm and 94.4% in the placebo arm, with a mean difference of 2.3% (95% CI: 0.3%, 4.2%; P = 0.022). Compared with women in the placebo arm, those who received multivitamins had a lower risk of severely inadequate GWG (RR: 0.90; 95% CI: 0.83, 0.97; P = 0.008) and inadequate GWG (RR: 0.95; 95% CI: 0.91, 0.99; P = 0.018). No significant difference was found in excessive GWG. CONCLUSIONS: Multivitamin supplementation increased GWG and reduced the risk of severely inadequate and inadequate GWG among pregnant women in Tanzania. Together with previously reported beneficial effects of the supplements on birth outcomes in low- and middle-income countries, our findings support scaling up the use of prenatal supplements that include multivitamins in addition to iron and folic acid.This trial was registered at clinicaltrials.gov as NCT00197548.

Linear Growth Spurts are Preceded by Higher Weight Gain Velocity and Followed by Weight Slowdowns Among Rural Children in Burkina Faso: A Longitudinal Study.

BACKGROUND: The temporal relationship between length (linear) and weight (ponderal) growth in early life is important to support optimal nutrition program design. Studies based on measures of attained size have established that wasting often precedes stunting, but such studies do not capture responsiveness of growth to previous compared with current conditions. As a result, the temporality of linear and ponderal growth relationships remain unclear. OBJECTIVES: We used growth velocity indicators to assess the temporal bidirectional relationships between linear and ponderal growth in children. METHODS: Using monthly anthropometric measurements from 5039 Burkinabè children enrolled at 6 months of age and followed until 28 months from August 2014 to December 2016, we employed multilevel mixed-effects models to investigate concurrent and lagged associations between linear and ponderal growth velocity, controlling for time trends, seasonality, and morbidity. RESULTS: Faster ponderal growth is associated with faster concurrent and subsequent linear growth (0.21-0.72 increase in length velocity z-score per unit increase in weight velocity z-score), while faster linear growth is associated with slower future weight gain (0.009-0.02 decrease in weight velocity z-score per unit increase in length velocity z-score), especially among children 9-14 months. Ponderal growth slows around the same time as peaks in morbidity, followed roughly a month later by slower linear growth. CONCLUSIONS: Use of velocity measures to assess temporal dependencies between linear and ponderal growth demonstrate that the same growth-limiting conditions likely affect both length and weight velocity, that slow ponderal growth likely limits subsequent linear growth, and that linear growth spurts may not be accompanied by sufficient increases in dietary intake to avoid slowdowns in weight gain.

Implications for quantifying early life growth trajectories of term-born infants using INTERGROWTH-21st newborn size standards at birth in conjunction with World Health Organization child growth standards in the postnatal period.

BACKGROUND: The INTERGROWTH-21st sex and gestational age (GA) specific newborn size standards (IG-NS) are intended to complement the World Health Organization Child Growth Standards (WHO-GS), which are not GA-specific. We examined the implications of using IG-NS at birth and WHO-GS at postnatal ages in longitudinal epidemiologic studies. OBJECTIVES: The aim of this study was to quantify the extent to which standardised measures of newborn size and growth are affected when using WHO-GS versus IG-NS at birth among term-born infants. METHODS: Data from two prenatal trials in Bangladesh (n = 755) and The Gambia (n = 522) were used to estimate and compare size at birth and growth from birth to 3 months when using WHO-GS only ('WHO-GS') versus IG-NS at birth and WHO-GS postnatally ('IG-NS'). Mean length-for-age (LAZ), weight-for-age (WAZ) and head circumference-for-age (HCAZ), and the prevalence of undernutrition (stunting: LAZ < -2SD; underweight: WAZ < -2SD; and microcephaly: HCAZ < -2SD) were estimated overall and by GA strata [early-term (370/7 -386/7 ), full-term (390/7 -406/7 ) and late-term (410/7 -430/7 )]. We used Bland-Altman plots to compare continuous indices and Kappa statistic to compare categorical indicators. RESULTS: At birth, mean LAZ, WAZ and HCAZ, and the prevalence of undernutrition were most similar among newborns between 39 and 40 weeks of GA when using WHO-GS versus IG-NS. However, anthropometric indices were systematically lower among early-term infants and higher among late-term infants when using WHO-GS versus IG-NS. Early-term and late-term infants demonstrated relatively faster and slower growth, respectively, when using WHO-GS versus IG-NS, with the direction and magnitude of differences varying between anthropometric indices. Individual-level differences in attained size and growth, when using WHO-GS versus IG-NS, were greater than 0.2 SD in magnitude for >60% of infants across all anthropometric indices. CONCLUSIONS: Using IG-NS at birth with WHO-GS postnatally is acceptable for full-term infants but may give a misleading interpretation of growth trajectories among early- and late-term infants.

Associations between Gestational Weight Gain Adequacy and Neonatal Outcomes in Tanzania.

INTRODUCTION: Gestational weight gain (GWG) is associated with fetal and newborn health; however, data from sub-Saharan Africa are limited. METHODS: We used data from a prenatal micronutrient supplementation trial among a cohort of human immunodeficiency virus-negative pregnant women in Dar es Salaam, Tanzania to estimate the relationships between GWG and neonatal outcomes. GWG adequacy was defined as the ratio of the total observed weight gain over the recommended weight gain based on the Institute of Medicine body mass index-specific guidelines. Neonatal outcomes assessed were stillbirth, perinatal death, preterm birth, low birthweight, macrosomia, small-for-gestational age (SGA), large-for-gestational age (LGA), stunting at birth, and microcephaly. Modified Poisson regressions with robust standard error were used to estimate the relative risk of newborn outcomes as a function of GWG adequacy. RESULTS: Of 7,561 women included in this study, 51% had severely inadequate (<70%) or inadequate GWG (70 to <90%), 31% had adequate GWG (90 to <125%), and 18% had excessive GWG (≥125%). Compared to adequate GWG, severely inadequate GWG was associated with a higher risk of low birthweight, SGA, stunting at birth, and microcephaly, whereas excessive GWG was associated with a higher risk of LGA and macrosomia. CONCLUSION: Interventions to support optimal GWG are needed and may contribute to preventing adverse neonatal outcomes.

Growth delay: an alternative measure of population health based on child height distributions.

BACKGROUND: Indicators of child height, such as mean height-for-age Z-scores (HAZ), height-for-age difference (HAD) and stunting prevalence, do not account for differences in population-average bone developmental stage. AIM: Propose a measure of child height that conveys the dependency of linear growth on stage rather than chronological age. SUBJECTS AND METHODS: Using Demographic and Health Surveys (2000-2018; 64 countries), we generated: (1) predicted HAZ at specific ages (HAZ regressed on age); (2) height-age (age at which mean height matches the WHO Growth Standards median); (3) Growth delay (GD), the difference between chronological age and height-age; (4) HAD; and (5) stunting prevalence. Metrics were compared based on secular trends within countries and age-related trajectories within surveys. RESULTS: In the most recent surveys (N = 64), GDs ranged from 1.9 to 19.1 months at 60 months chronological age. Cross-sectionally, HAZ, HAD and GD were perfectly correlated, and showed similar secular trends. However, age-related trajectories differed across metrics. Accumulating GD with age demonstrated growth faltering as slower than expected growth for children of the same height-age. Resumption of growth at the median for height-age was rarely observed. CONCLUSION: GD is a population-level measure of child health that reflects the role of delayed skeletal development in linear growth faltering.

Effect of Correcting the Postnatal Age of Preterm-Born Children on Measures of Associations Between Infant Length-for-Age z Scores and Mid-Childhood Outcomes.

Child growth standards are commonly used to derive age- and sex-standardized anthropometric indices but are often inappropriately applied to preterm-born children (<37 weeks of gestational age (GA)) in epidemiology studies. Using the 2004 Pelotas Birth Cohort, we examined the impact of correcting for GA in the application of child growth standards on the magnitude and direction of associations in 2 a priori-selected exposure-outcome scenarios: infant length-for-age z score (LAZ) and mid-childhood body mass index (scenario A), and infant LAZ and mid-childhood intelligence quotient (scenario B). GA was a confounder that had a strong (scenario A) or weak (scenario B) association with the outcome. Compared with uncorrected postnatal age, using GA-corrected postnatal age attenuated the magnitude of associations, particularly in early infancy, and changed inferences for associations at birth. Although differences in the magnitude of associations were small when GA was weakly associated with the outcome, model fit was meaningfully improved using corrected postnatal age. When estimating population-averaged associations with early childhood growth in studies where preterm- and term-born children are included, incorporating heterogeneity in GA at birth in the age scale used to standardize anthropometric indices postnatally provides a useful strategy to reduce standardization errors.

Gestational Age, Birth Weight, and Neurocognitive Development in Adolescents in Tanzania.

OBJECTIVES: To investigate the association between gestational age, birthweight, and birthweight adjusted for gestational age, with domains of neurocognitive development and behavioral problems in adolescents in Tanzania. STUDY DESIGN: Data from a long-term follow-up of adolescents aged 11-15 years born to women previously enrolled in a randomized controlled trial of prenatal multiple micronutrient supplementation in Dar es Salaam, Tanzania, were used. A battery of neurodevelopmental tests were administered to measure adolescent general intelligence, executive function, and behavioral problems. The INTERGROWTH-21st newborn anthropometric standards were used to derive birthweight for gestational age z-scores. We assessed the shape of relationships using restricted cubic splines and estimated the associations of gestational age, birthweight, and birthweight for gestational age z-score with adolescent development using multivariable linear regressions. RESULTS: Among adolescents studied (n = 421), higher gestational age (per week), birthweight (per 100 grams), and birthweight for gestational age z-score (per SD) were linearly associated with higher intelligence score (adjusted standardized mean difference, 0.05 SD [95% CI, 0.01-0.09], 0.04 SD [95% CI, 0.02-0.06], and 0.09 SD [95% CI, 0.01-0.17], respectively). Birthweight and birthweight for gestational age z-score, but not gestational age, were also associated with improved executive function. Low birthweight (<2500 g) was associated with lower intelligence and executive function scores. Associations between birthweight and executive function were stronger among adolescents born to women with higher education. CONCLUSIONS: The duration of gestation and birthweight were positively associated with adolescent neurodevelopment in Tanzania. These findings suggest that interventions to improve birth outcomes may also benefit adolescent cognitive function.

Methodological approaches to imputing early-pregnancy weight based on weight measures collected during pregnancy.

BACKGROUND: Early pregnancy weights are needed to quantify gestational weight gain accurately. Different methods have been used in previous studies to impute early-pregnancy weights. However, no studies have systematically compared imputed weight accuracy across different imputation techniques. This study aimed to compare four methodological approaches to imputing early-pregnancy weight, using repeated measures of pregnancy weights collected from two pregnancy cohorts in Tanzania. METHODS: The mean gestational ages at enrollment were 17.8 weeks for Study I and 10.0 weeks for Study II. Given the gestational age distributions at enrollment, early-pregnancy weights were extrapolated for Study I and interpolated for Study II. The four imputation approaches included: (i) simple imputation based on the nearest measure, (ii) simple arithmetic imputation based on the nearest two measures, (iii) mixed-effects models, and (iv) marginal models with generalized estimating equations. For the mixed-effects model and the marginal model with generalized estimating equation methods, imputation accuracy was further compared across varying degrees of model flexibility by fitting splines and polynomial terms. Additional analyses included dropping third-trimester weights, adding covariate to the models, and log-transforming weight before imputation. Mean absolute error was used to quantify imputation accuracy. RESULTS: Study I included 1472 women with 6272 weight measures; Study II included 2131 individuals with 11,775 weight measures. Among the four imputation approaches, mixed-effects models had the highest accuracy (smallest mean absolute error: 1.99 kg and 1.60 kg for Studies I and II, respectively), while the other three approaches showed similar degrees of accuracy. Depending on the underlying data structure, allowing appropriate degree of model flexibility and dropping remote pregnancy weight measures may further improve the imputation performance. CONCLUSIONS: Mixed-effects models had superior performance in imputing early-pregnancy weight compared to other commonly used strategies.

Plasma concentrations of leptin at mid-pregnancy are associated with gestational weight gain among pregnant women in Tanzania: a prospective cohort study.

BACKGROUND: Gestational weight gain (GWG) has critical implications for maternal and child health. Inflammation and angiogenesis are implicated in various aspects of maternal metabolism that may play a role in gestational weight gain. The associations of inflammatory, angiogenic, and metabolic pathways with GWG are yet to be elucidated. This study evaluated associations between a panel of inflammatory, angiogenic, and metabolic proteins measured in mid-pregnancy and gestational weight gain. METHODS: Pregnant women were enrolled from Dar es Salaam, Tanzania, between 2001 and 2004. The participants were enrolled at mid-pregnancy (12 to 27 weeks of gestation) and followed up until delivery. This analysis focused on a cohort of 1002 women who were primigravid, had singleton live births, had longitudinal measures of gestational weight, and whose mid-pregnancy plasma samples underwent analysis for 18 proteins. RESULTS: Higher plasma concentrations of leptin (mean difference in GWG percent adequacy comparing highest with lowest quartiles: 10.24; 95% CI 3.31, 17.16; p-trend = 0.003) and chitinase-3-like protein-1 (CH3L1) (mean difference in GWG percent adequacy comparing highest with lowest quartiles: 7.02; 95% CI 0.31, 13.72; p-trend = 0.007) were associated with greater GWG in a dose-response pattern. Higher leptin concentrations were associated with a lower risk of inadequate GWG (risk ratio comparing highest with lowest quartiles: 0.77; 95% CI 0.65, 0.91; p-trend = 0.001) and a higher risk of excessive GWG (risk ratio comparing highest with lowest quartiles: 1.57; 95% CI 1.03, 2.39; p-trend = 0.03). Higher CH3L1 concentrations were associated with a higher risk of excessive GWG (p-trend = 0.007). The associations of leptin and CH3L1 with inadequate GWG were stronger during the second than the third trimester. The other 16 proteins examined were not significantly associated with GWG. CONCLUSIONS: Mid-pregnancy plasma leptin concentrations may be associated with GWG and have clinical predictive utility in identifying women at a higher risk of inadequate or excessive gestational weight gain.

A scoping review of research on policies to address child undernutrition in the Millennium Development Goals era.

OBJECTIVE: The breadth of research on the impact of nutrition-specific policies to address child undernutrition is not well documented. This review maps the evidence base and identifies gaps on such policies. DESIGN: We systematically searched Medline, Embase, PAIS Index for public policy, Scopus and Web of Science databases to identify eligible studies. Key study characteristics, including research design, type of policy, time span of policy before impact assessment, child age at outcome assessment and types of outcomes assessed, were abstracted in duplicate. SETTING: Low-, middle- and high-income countries. PARTICIPANTS: Studies were eligible for inclusion if they aimed to assess the impact of population-level nutrition-specific policies on undernutrition among children under 10 years of age. RESULTS: Of the 5646 abstracts screened, eighty-three studies were included. A range of policies to address child undernutrition were evaluated; the majority were related to micronutrient fortification. Most studies were observational, reported on mandatory regional or sub-national polices, were conducted in high-income countries and evaluated policies within 1 year of implementation. A narrow set of health outcomes were evaluated, most commonly iodine deficiency disorders and neural tube defects. CONCLUSIONS: Nutrition policies were commonly associated with improved child nutritional status and health. However, this evidence is primarily based on limited settings and on a limited number of outcomes. Further research is needed to assess the longer-term impact of a broader range of nutrition policies on child health, particularly in low- and middle-income countries.

Use and Misuse of Stunting as a Measure of Child Health.

The term "stunting" has become pervasive in international nutrition and child health research, program, and policy circles. Although originally intended as a population-level statistical indicator of children's social and economic deprivation, the conventional anthropometric definition of stunting (height-for-age z scores <-2 SD) is now widely used to define chronic malnutrition. Epidemiologists often portray it as a disease, making inferences about the causes of growth faltering based on comparisons between stunted (i.e., undernourished) and nonstunted children. Stunting is commonly used to monitor public health and nutrition program effectiveness alongside calls for the "elimination of stunting." However, there is no biological basis for the -2 SD cutoff to define stunting, making it a poor individual-level classifier of malnutrition or disease. In fact, in many low- and middle-income countries, children above and below the threshold are similarly affected by growth-limiting exposures. We argue that the common use of stunting as an indicator of child linear growth has contributed to unsubstantiated assumptions about the biological mechanisms underlying linear growth impairment in low- and middle-income countries and has led to a systematic underestimation of the burden of linear growth deficits among children in low-resource settings. Moreover, because nutrition-specific short-term public health interventions may result in relatively minor changes in child height, the use of stunting prevalence to monitor health or nutrition program effectiveness may be inappropriate. A more nuanced approach to the application and interpretation of stunting as an indicator in child growth research and public health programming is warranted.

Effect of correcting for gestational age at birth on population prevalence of early childhood undernutrition.

BACKGROUND: Postmenstrual and/or gestational age-corrected age (CA) is required to apply child growth standards to children born preterm (< 37 weeks gestational age). Yet, CA is rarely used in epidemiologic studies in low- and middle-income countries (LMICs), which may bias population estimates of childhood undernutrition. To evaluate the effect of accounting for GA in the application of growth standards, we used GA-specific standards at birth (INTERGROWTH-21st newborn size standards) in conjunction with CA for preterm-born children in the application of World Health Organization Child Growth Standards postnatally (referred to as 'CA' strategy) versus postnatal age for all children, to estimate mean length-for-age (LAZ) and weight-for-age (WAZ) z scores at 0, 3, 12, 24, and 48-months of age in the 2004 Pelotas (Brazil) Birth Cohort. RESULTS: At birth (n = 4066), mean LAZ was higher and the prevalence of stunting (LAZ < -2) was lower using CA versus postnatal age (mean ± SD): - 0.36 ± 1.19 versus - 0.67 ± 1.32; and 8.3 versus 11.6%, respectively. Odds ratio (OR) and population attributable risk (PAR) of stunting due to preterm birth were attenuated and changed inferences using CA versus postnatal age at birth [OR, 95% confidence interval (CI): 1.32 (95% CI 0.95, 1.82) vs 14.7 (95% CI 11.7, 18.4); PAR 3.1 vs 42.9%]; differences in inferences persisted at 3-months. At 12, 24, and 48-months, preterm birth was associated with stunting, but ORs/PARs remained attenuated using CA compared to postnatal age. Findings were similar for weight-for-age z scores. CONCLUSIONS: Population-based epidemiologic studies in LMICs in which GA is unused or unavailable may overestimate the prevalence of early childhood undernutrition and inflate the fraction of undernutrition attributable to preterm birth.

Prenatal vitamin D supplementation and infant vitamin D status in Bangladesh.

OBJECTIVE: To determine the effect of prenatal maternal vitamin D supplementation on infant vitamin D status in a tropical region where vitamin D supplementation is not routine. DESIGN: A prospective observational follow-up of a randomized trial. SETTING: Maternal-child health facility in Dhaka, Bangladesh (23°N). SUBJECTS: Infants born to pregnant women (n 160) randomized to receive 875 µg (35 000 IU) cholecalciferol (vitamin D3) per week (VD) or placebo (PL) during the third trimester were followed from birth until 6 months of age (n 115). Infant serum 25-hydroxyvitamin D concentration (25(OH)D) was measured at <1, 2, 4 and 6 months of age. RESULTS: Mean infant 25(OH)D was higher in the VD v. PL group at <1 month of age (mean (sd): 80 (20) nmol/l v. 22 (18) nmol/l; P<0·001), but the difference was attenuated by 2 months (52 (19) nmol/l v. 40 (23) nmol/l; P=0·05). Groups were similar at 4 months (P=0·40) and 6 months (n 72; P=0·26). In the PL group, mean infant 25(OH)D increased to 78 (95 % CI 67, 88) nmol/l by 6 months of age (n 34). 25(OH)D was higher with infant formula-feeding and higher in summer v. winter. CONCLUSIONS: Prenatal third-trimester vitamin D supplementation (875 µg (35 000 IU)/week) significantly ameliorated infant vitamin D status during the neonatal period when the risk of vitamin D deficiency is greatest. Further research is warranted to determine factors that contribute to the rise in 25(OH)D during the first 6 months of life among breast-fed infants in this setting.