Predictors of 25-hydroxyvitamin D concentrations during pregnancy: A longitudinal analysis in the Brazilian Amazon.

OBJECTIVES: To determine predictors of 25-hydroxyvitamin D3 (25(OH)D3) concentrations (25th, 50th, and 75th percentiles) in the third trimester of pregnancy. SUBJECTS/METHODS: Data on sociodemographic, obstetric, lifestyle and pregnancy characteristics, including serum 25(OH)D3 and retinol, were collected among 448 pregnant women who participated in the Maternal and Child Health and Nutrition in Acre, Brazil (MINA-Brazil Study) in Cruzeiro do Sul, Brazilian Amazon (latitude 7°S). Simultaneous-quantile regression was fitted to prospectively assess predictors at the 25th, 50th and 75th percentiles of 25(OH)D3 concentrations. RESULTS: In the third trimester, 25(OH)D3 <50 nmol/L was observed in 26% of pregnant women. Exposure to the Amazonian dry season during follow-up and vitamin D status ≥75 nmol/L in the second trimester of pregnancy were positively associated with 25(OH)D3 concentrations in the third trimester. Pregnant women who were the main providers of family income presented lower 25(OH)D3 concentrations (50th and 75th percentiles: -15 nmol/L, 95%CI -24; -3, p = 0.02, and -22 nmol/L, 95%CI -36; -7, p = 0.004, respectively), as well as those with sustained vitamin A insufficiency (25th and 50th percentiles: -27 nmol/L, 95%CI -40; -15, p < 0.001, and -17 nmol/L, 95%CI -33; -1, p = 0.04, respectively). Sun protection practices had a smaller negative impact on 25(OH)D3, restricted to participants whose concentrations were at the 25th percentile of the distribution. CONCLUSIONS: Seasonality and vitamin A status were important predictors of 25(OH)D3 concentrations in the third trimester. Adequate exposure to sunlight and dietary sources of vitamin A within safe intake levels may help ensuring a good nutritional status of vitamin D during pregnancy.

Fatores associados a medidas biométricas fetais pequenas para idade gestacional no Estudo MINA-Brasil / Factors associated with small-for-gestational-age fetal biometric measurements in the MINA-Brazil Study

Introdução - As elevadas taxas de mortalidade neonatal e a prevalência de bebês nascidos pequenos para idade gestacional (PIG) ainda apresentadas por regiões de baixa e média renda indicam a necessidade de investigação sobre fatores que influenciam o crescimento fetal. Medidas biométricas fetais

Introduction Elevated rates of neonatal mortality and small-for-gestational-age (SGA) babies in low- and middle-income regions indicate the need to investigate factors associated with fetal growth. Fetal biometric measurements below the 10th percentile for gestational age (GA) reflect failure in achieving growth potential and provide opportunities for prenatal interventions. Objective To investigate factors associated with fetal biometric measurements below the 10th percentile assessed at early third trimester among pregnant women in the MINA-Brazil study. Methods This was a prospective analysis of pregnant women living in the urban area of Cruzeiro do Sul (AC), followed up since the antenatal period. Screening of participants took place from February 2015 to January 2016. A sociodemographic and health history interview was carried out along with two clinical assessments, scheduled between the second and third trimesters of pregnancy, to collect data on lifestyle factors and complications during pregnancy, anthropometric evaluation, blood collection, and ultrasound scan assessing fetal biometric measurements of head circumference (HC), abdominal circumference (AC) and femoral length (FL). Poisson regression models with hierarchical selection of variables were fitted for factors associated with occurrence of fetal measurements below the 10th percentile at early third trimester. Prevalence ratios (PR) and 95% confidence intervals (95%CI) were estimated. Results Among 426 participants (mean age 25 years (SD 6.4) and gestational age 27.8 weeks (SD 1.7)), 11.3%, 8.9% e 9.4% had fetuses with HC, AC, FL below the 10th percentile at early third trimester. Fetal biometric measurements below the 10th percentile were negatively associated with higher maternal education level, which denoted over 50% of protection (HC: PR 0.47, 95%CI 0.28; 0.81; AC: PR 0.48, 95%CI 0.26; 0.87; and FL: PR 0.48, 95%CI 0.27; 0.86). Adjusted for maternal education level, nulliparity (PR 1.94, 95%CI 1.10; 3.43), higher pre-gestational body mass index (BMI) (PR 1.06, 95%CI 1.01; 1.11), and pre-gestational alcohol consumption (PR 1.80, 95%CI 0.98; 3.30) were associated with HC measurements below the 10th percentile. Maternal height (p for trend 0.039) and pre-gestational alcohol consumption (PR 2.55, 95%CI 1.31; 4.96) were also associated with AC measurements below the 10th percentile. Association between higher average screen time per day during antenatal follow-up and FL measurements below the 10th percentile were observed as well (p for trend 0.031). Higher maternal education level, which may provide better material and non-material conditions, seems to protect fetal growth from failure to reach potential fetal size for GA. Positive associations observed with obstetric and antenatal conditions may be mediated by biological factors or gestational dysfunctions to incur in fetal measurements below the 10th percentile. Conclusion The occurrence of fetal biometric measurements below the 10th percentile for GA and their associated factors corroborate pre-pregnancy and antenatal care improvements anchored in equity policies, and for new strategies prior to birth that optimize the window of opportunity in the first thousand days of life.