Effect of Vitamin A status during pregnancy on maternal anemia and newborn birth weight: results from a cohort study in the Western Brazilian Amazon

Impact of Vitamin A Deficiency on Iron Metabolism and Anemia: A Historical Perspective and Research Advances

Vitamin A deficiency (VAD) and iron deficiency anemia coexist around the world, particularly in children and women of reproductive age in low- and middle-income countries. Within this scenario, there is a known interaction between vitamin A and iron, and it has been postulated that lack of vitamin A impairs iron metabolism, leading to vitamin A deficiency anemia (VADA). Current animal, epidemiological, and clinical studies support this notion. The objective of this study was to review the current literature on proposed metabolic mechanisms regarding how VAD modulates iron metabolism leading to anemia. To attain this objective, a literature search was conducted of research publications in the related field, without date restriction, using PubMed, Scopus, Google Scholar, and the University of Illinois's reference system. The data support the essentiality of vitamin A for normal erythropoiesis. It indicates that, in VAD, iron mobilization is impaired, and that this mineral accumulates in the liver and spleen, making it less available for erythropoiesis. A triggering factor for the development of VADA seems to be inflammation and systemic infection, which release cytokines that upregulate the production of hepcidin by the liver. VAD may also increase hepcidin directly without the involvement of inflammation or infection. The elevated hepcidin, in turn, lowers circulating iron and sequesters iron in storage depots, downregulating erythropoietin, leading to inefficient erythropoiesis, decreased hemoglobin (Hb) production, and (subsequently) anemia. VAD may also impact the expression of iron regulatory protein 2 (IRP2), and thus affect intracellular iron metabolism gene expression. VADA is not due to iron deficiency, but to a redistribution of iron in the body. Understanding the mechanism of VADA will assist in designing more effective strategies for combating anemia worldwide.

Genetic predicted causal inferences between antioxidants and birth weight

Observational studies have suggested a relationship between antioxidants and birth weight. However, the causal association remains unclear. The aim of this study was to assess the causal relationship between antioxidants and birth weight. Genome wide association study (GWAS) summary statistics for 4 endogenous and 7 exogenous antioxidants, as well as birth weight were obtained from GWAS studies and UK biobank. A two-sample Mendelian randomization (MR) analysis was conducted with fixed-effects model inverse variance weighted (IVW) as the primary analytical method, while MR Egger and weighted median used as auxiliary. A series of sensitivity analyses were conducted to verify the robustness of the results. The MR results revealed that genetically predicted higher superoxide dismutase (SOD) (β = 0.025; 95% CI: 0.008, 0.043; p = 0.005) and zinc (β = 0.030; 95% CI: 0.013, 0.047; p = 0.001) levels were associated with higher birth weight. Sensitivity analysis verified the robustness of the MR results. Our study reinforced the existing evidence supporting a significant positive association between SOD and zinc with birth weight, providing new genetic evidence for antioxidant supplementation during pregnancy to prevent low birth weight infants. Further deeper comprehension studies are warranted to confirm these findings.

Vitamin a supplementation during pregnancy in shaping child growth outcomes: A meta-analysis

Abnormal fetal growth increases risks of childhood health complications. Vitamin A supplementation (VAS) is highly accessible, but literature inconsistency regarding effects of maternal VAS on fetal and childhood growth outcomes exists, deterring pregnant women from VAS during pregnancy. This meta-analysis aimed to analyze effects of vitamin A only or vitamin A + co-intervention during pregnancy in healthy mothers (MH) or with complications (MC, night blindness and HIV positive) on perinatal growth outcomes, also assess VAS dose impacts. The Cochrane Library, PubMed, ScienceDirect, Scopus, Embase and Web of Science databases were searched from inception to July 15, 2021. We covered subgroup analyses, including VAS in MH or MC within randomized controlled trial (RCT) or observational studies (OS). Fifty-five studies were included in this meta-analysis (426,098 pregnancies). Vitamin A decreased risk of preterm birth by 9% in MH-RCT (P < 0.001), by 62% in MH-OS (P = 0.029), by 10% in MC-RCT (P = 0.089); decreased LBW by 24% in MC-RCT (P = 0.032); increased neonatal weight in MC-RCT (SMD 0.96; P = 0.051). Besides, vitamin A + co-intervention decreased risks of preterm by 18% in MH-OS (P = 0.021); LBW by 25% in MH-OS (P < 0.001); by 32% in MC-RCT (P = 0.006); decreased neonatal defects by 33% in MH-OS (P = 0.064); decreased anemia by 25% in MH-OS (P = 0.0003); increased neonatal weight in MH-OS (SMD 0.51; P = 0.014); and increased neonatal length in MH-OS (SMD 1.83; P = 0.013). Meta-regression of VAS dose with individual outcomes was not significant, and no side effects were observed for VAS doses up to 4000 mcg (RAE/d). Regardless of maternal health conditions, VAS during pregnancy can safely and effectively improve fetal development and neonatal health even in mothers without VAD.

The association between umbilical cord blood fat-soluble vitamin concentrations and infant birth weight

Background

Fat-soluble vitamins, including vitamins A, D and E, play an important role in the regulation of glucose and lipid metabolism, and may affect infant birth weight. Evidence on the association of birthweight with fat-soluble vitamins is controversial. Therefore, this study aims is to determine the associations of birthweight with vitamin A, D, and E concentrations in cord blood.

Methods

A total of 199 mother-infant pairs were enrolled in the study. According to gestational age and birth weight, the mother-infant pairs were divided into small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA). The Vitamin A, D, and E concentrations in serum were measured by high-performance liquid chromatography tandem-mass spectrometry.

Results

The concentrations of vitamin A in the SGA group were significantly lower than those in the AGA and LGA groups. The concentrations of vitamin E in the SGA group were significantly higher than those in the AGA and LGA groups. However, no significant differences were observed in vitamin D among the three groups. Being male (β = 0.317, p < 0.001) and birth weight (β = 0.229, p = 0.014) were positively correlated with the levels of vitamin A. Birth weight (β = -0.213, p= 0.026) was correlated with lower levels of vitamin E. No correlation was found between influencing Factors and the levels of vitamin D (p> 0.05). After adjusting for gestational age, sex, mother's age, delivery mode, pre-pregnancy BMI, and weight gain during pregnancy, the levels of cord blood vitamin A were positively correlated with birth weight (p=0.012).

Conclusion

The infant's birth weight is associated with the levels of cord blood vitamins A and E. The dysregulation of vitamins A and E in infants may be a risk factor for fetal growth and future metabolic diseases.

Plasma Retinol Concentrations and Dietary Intakes of Mother-Infant Sets in Singleton versus Twin Pregnancy

Vitamin A (retinol) is essential for normal fetal development, but the recommendation for maternal dietary intake (Retinol Activity Equivalent, RAE) does not differ for singleton vs. twin pregnancy, despite the limited evaluation of retinol status. Therefore, this study aimed to evaluate plasma retinol concentrations and deficiency status in mother-infant sets from singleton vs. twin pregnancies as well as maternal RAE intake. A total of 21 mother-infant sets were included (14 singleton, 7 twin). The HPLC and LC-MS/HS evaluated the plasma retinol concentration, and data were analyzed using the Mann-Whitney U test. Plasma retinol was significantly lower in twin vs. singleton pregnancies in both maternal (192.2 vs. 312.1 vs. mcg/L, p = 0.002) and umbilical cord (UC) samples (102.5 vs. 154.4 vs. mcg/L, p = 0.002). The prevalence of serum-defined vitamin A deficiency (VAD) <200.6 mcg/L was higher in twins vs. singletons for both maternal (57% vs. 7%, p = 0.031) and UC samples (100% vs. 0%, p < 0.001), despite a similar RAE intake (2178 vs. 1862 mcg/day, p = 0.603). Twin pregnancies demonstrated a higher likelihood of vitamin A deficiency in mothers, with an odds ratio of 17.3 (95% CI: 1.4 to 216.6). This study suggests twin pregnancy may be associated with VAD deficiency. Further research is needed to determine optimal maternal dietary recommendations during twin gestation.

A non-invasive machine learning mechanism for early disease recognition on Twitter: The case of anemia

Social media sites, such as Twitter, provide the means for users to share their stories, feelings, and health conditions during the disease course. Anemia, the most common type of blood disorder, is recognized as a major public health problem all over the world. Yet very few studies have explored the potential of recognizing anemia from online posts. This study proposed a novel mechanism for recognizing anemia based on the associations between disease symptoms and patients' emotions posted on the Twitter platform. We used k-means and Latent Dirichlet Allocation (LDA) algorithms to group similar tweets and to identify hidden disease topics. Both disease emotions and symptoms were mapped using the Apriori algorithm. The proposed approach was evaluated using a number of classifiers. A higher prediction accuracy of 98.96 % was achieved using Sequential Minimal Optimization (SMO). The results revealed that fear and sadness emotions are dominant among anemic patients. The proposed mechanism is the first of its kind to diagnose anemia using textual information posted on social media sites. It can advance the development of intelligent health monitoring systems and clinical decision-support systems.

Common mental disorders in pregnancy and postnatal depressive symptoms in the MINA-Brazil study: occurrence and associated factors

OBJECTIVE

To investigate the occurrence and factors associated with common mental disorders in pregnancy and depressive symptoms in postpartum, as well as the association between both in the Brazilian Western Amazon.

METHODS

This is a prospective cohort in the MINA-Brazil study with women who received primary health care in the town of Cruzeiro do Sul, Acre State. We performed two clinical evaluations during pregnancy (the first: 16–20 weeks; the second: 28 gestational weeks) and three postpartum evaluations (at 3, 6 and 12 months), in which demographic and socioeconomic, gestational, lifestyle and clinical data were collected. We used the Self-Reported Questionnaire (score ≥ 8) to screen the gestational common mental disorder and the Edinburgh Postnatal Depression Scale (score ≥ 10) to identify postpartum depressive symptoms. We used adjusted ordinal logistic regression to investigate the relationship between the covariates and the occurrence of common mental disorders in pregnancy and postpartum depressive symptomatology.

RESULTS

A total of 461 women completed the two clinical evaluations in pregnancy; of these, 247 completed the three postpartum evaluations. The occurrence of common mental disorder during pregnancy was 36.2% and 24.5% in the first and second evaluations, respectively, and the cumulative incidence was 9.2%. In addition, 50.3% maintained the disorder between evaluations. During postpartum, approximately 20% of the mothers presented depressive symptoms during the first year of their children’s lives. Parity (≥ 2) was associated with common mental disorders, while low maternal education was associated with postpartum depressive symptoms. Women with a common mental disorder in both evaluations during pregnancy were 5.6 times more likely (95%CI: 2.50–12.60) to develop postpartum depressive symptoms.

CONCLUSION

The occurrence of common mental disorder at any time assessed during pregnancy, but especially its persistence from the second trimester, was strongly associated with depressive symptoms after childbirth. These findings highlight the need for early screening and monitoring of the mental health of pregnant women at the start of prenatal care in order to reduce possible negative impacts on the health of the mother-child binomial caused by such events.

Prevalence of vitamin A deficiency in women of childbearing age in Brazil: a systematic review and meta-analysis

Vitamin A is an essential micronutrient, especially during pregnancy. We aimed to assess the prevalence of vitamin A deficiency in Brazilian women of childbearing age. We conducted a systematic review with meta-analysis of studies that assessed vitamin A deficiency in women of childbearing age following the registered protocol (CRD42020171856). Independent peer researchers selected the studies retrieved from MEDLINE, Embase, Scopus and other sources. Data from the eligible studies were extracted in pairs and assessed for methodological quality. The prevalence of vitamin A deficiency (< 0·70 µmol/l or <0·20 µg/dl) and 95 % CI was combined by meta-analysis, and heterogeneity was estimated by I². Out of 3610 screened records, thirty-two studies were included, which assessed 12 577 women from 1965 to 2017, mostly in maternity hospitals. Main limitations of the studies were in sample frame (30/32) and sampling method (29/32). Deficiency occurred in 13 % (95 % CI 9·4, 17·2 %; I² = 97 %) of all women and was higher in pregnant women (16·1 %; 95 % CI 5·6, 30·6 %; I² = 98 %) than non-pregnant women (12·3 %; 95 % CI 8·4, 16·8 %; I² = 96 %). The prevalence increased according to the decade, from 9·5 % (95 % CI 1·9–21·6 %; I² = 98 %) up to 1990, 10·8 % (95 % CI 7·9, 14·2 %; I² = 86 %) in the 2000s and 17·8 % (95 % CI 8·7, 29·0 %; I² = 98 %) in the 2010s. Over 10 % of Brazilian women in childbearing age were deficient in vitamin A. Higher prevalence was observed in pregnant women, and deficiency seemed to be increasing over the decades. Low representativeness of the studies, mainly based on convenience sampling that included pregnant, postpartum, lactating and non-pregnant women, as well as high heterogeneity, limits the findings.

Leisure-time physical activity in Amazonian pregnant women and offspring birth weight: A prospective cohort study

Compelling evidence supports the current international recommendation of at least 150 min/week of leisure-time physical activity (LTPA) during pregnancy. However, the potential relationship between LTPA and birth weight (BW) remains unclear in low- and middle-income countries. The purpose of this study was to examine the association between LTPA during pregnancy and offspring BW in an Amazonian population. Prospective cohort study was carried-out with 500 pregnant women and their offspring followed-up in the MINA-Brazil study, which was conducted in Cruzeiro do Sul, Western Brazilian Amazon. LTPA was assessed in the second (mean 19.6, SD 2.4 weeks) and third (mean 27.8, SD 1.6 weeks) gestational trimesters by a standardised interview and categorised according to the recommended cut-off of at least 150 min/week. We calculated offspring BW z-scores by sex and gestational age. We then explored the effect of LTPA during pregnancy on offspring BW, the association between LTPA and small-for-gestational-age (SGA) or large-for-gestational-age (LGA) births, and the mediating role of excessive and insufficient gestational weight gain (GWG). At least 150 min/week of LTPA during the third gestational trimester was associated with an offspring BW decrease of -0.35 z-score (95% CI: -0.65, -0.05) or -147.9 grams (95% CI: -260.9, -14.8), without increasing the frequency of SGA foetuses either in the second or third gestational trimester (p > 0.05). Excessive GWG mediated the effect of LTPA on the offspring BW (indirect effect = -0.05 z-score [95% CI: -0.10, -0.00] or -34.7 grams (95% CI: -66.1, -3.3]). This mediation effect was not observed for insufficient GWG. LTPA in the third, but not in the second, trimester of pregnancy was inversely associated with offspring BW without increasing the frequency of SGA, an effect that was partly mediated by excessive GWG.

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 (25^th, 50^th, and 75^th 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 25^th, 50^th and 75^th 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 (50^th and 75^th 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 (25^th and 50^th 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 25^th 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.

Geographic and socio-demographic determinants of plasma retinol concentrations in Chinese pregnant and lactating women

PURPOSE

To examine plasma retinol status and its determinants in Chinese pregnant or lactating women.

METHODS

A cross-sectional study involving 1211 healthy women in mid-pregnancy, late pregnancy, or lactation was conducted in northern, central, and southern China. Plasma retinol concentration was determined by high-performance liquid chromatography. Multivariate quantile regression or modified Poisson regression was used to estimate adjusted medians, or to examine the associations of suboptimal retinol concentration (< 1.05 µmol/L) with various factors.

RESULTS

The overall median (interquartile range) retinol concentration was 1.25 (1.06-1.46) µmol/L. The adjusted concentration was higher in women at lactation (1.39 [1.20-1.63] µmol/L) and mid-pregnancy (1.26 [1.10-1.44] µmol/L) than late pregnancy (1.07 [0.92-1.28] µmol/L), and higher in women in the central area (1.34 [1.18-1.49] µmol/L) and the north (1.26 [1.10-1.43] µmol/L) than the south (1.19 [1.07-1.31] µmol/L). The retinol concentration was more likely to be low in women with lower pre-pregnancy BMI, younger age, less education, and in lactating women who had a caesarean birth or were breastfeeding exclusively. A total of 290 (24.0%) women had a suboptimal retinol concentration, and the prevalence was higher in women at late pregnancy, residing in the south, with younger age, and having underweight pre-pregnancy.

CONCLUSION

About one-fourth of pregnant or lactating women in China had suboptimal retinol concentrations that varied with phases of pregnancy and lactation, region of residence, and socio-demographic characteristics, indicating a need for population-specific public health strategies to optimize vitamin A status.

Associations between Maternal Dietary Patterns and Infant Birth Weight in the NISAMI Cohort: A Structural Equation Modeling Analysis

The mother’s diet during pregnancy is associated with maternal and child health. However, there are few studies with moderation analysis on maternal dietary patterns and infant birth weight. We aim to analyse the association between dietary patterns during pregnancy and birth weight. A prospective cohort study was performed with pregnant women registered with the prenatal service (Bahia, Brazil). A food frequency questionnaire was used to evaluate dietary intake. Birth weight was measured by a prenatal service team. Statistical analyses were performed using factor analysis with a principal component extraction technique and structural equation modelling. The mean age of the pregnant women was 27 years old (SD: 5.5) and the mean birth weight was 3341.18 g. It was observed that alcohol consumption (p = 0.05) and weight-gain during pregnancy (p = 0.05) were associated with birth weight. Four patterns of dietary consumption were identified for each trimester of the pregnancy evaluated. Adherence to the “Meat, Eggs, Fried Snacks and Processed foods” dietary pattern (pattern 1) and the “Sugars and Sweets” dietary pattern (pattern 4) in the third trimester directly reduced birth weight, by 98.42 g (Confidence interval (CI) 95%: 24.26, 172.59) and 92.03 g (CI 95%: 39.88, 165.30), respectively. It was also observed that insufficient dietary consumption in the third trimester increases maternal complications during pregnancy, indirectly reducing birth weight by 145 g (CI 95%: −21.39, −211.45). Inadequate dietary intake in the third trimester appears to have negative results on birth weight, directly and indirectly, but more studies are needed to clarify these causal paths, especially investigations of the influence of the maternal dietary pattern on the infant gut microbiota and the impacts on perinatal outcomes.

Vitamin A Requirements in Pregnancy and Lactation

Pregnancy and lactation are critical life stages with unique nutritional requirements, including for vitamin A (VA). Current DRIs for VA were published in 2001. The objective of this review was to identify and categorize evidence related to VA requirements in pregnancy and lactation since these DRIs were formulated. We searched MEDLINE and included articles according to an analytic framework of maternal VA exposure on status and health outcomes in the mother-child dyad. Intermediate and indirect evidence supports that maternal VA intakes can impact the mother's VA status, breastmilk, and health outcomes, as well as the child's VA status and select health outcomes. Food-based approaches can lead to more sustained, sufficient VA status in mothers and children. Research needs include further study linking maternal VA intakes on maternal and child VA status, and further associations with outcomes to determine intake requirements to optimize health.

[Relationship of plasma vitamin A levels between neonates and pregnant women in third trimester]

OBJECTIVE

To study the correlation of plasma vitamin A (VitA) levels between neonates and pregnant women in third trimester.

METHODS

A total of 688 pregnant women were recruited in Yuanshi and Laoting counties of Hebei Province, from May to June 2009. Venous blood samples of women before delivery and cord blood samples of newborns were collected and measured for retinol (retinol concentration was used to reflect VitA level) using high performance liquid chromatography assay. According to venous blood plasma retinol concentration, maternal VitA nutritional status was divided into deficiency (<0.70 μmol/L), marginal deficiency (0.70-<1.05 μmol/L), and sufficiency (≥1.05 μmol/L). According to cord blood plasma retinol concentration, neonatal VitA nutritional status was divided into deficiency (<0.35 μmol/L), marginal deficiency (0.35-<0.70 μmol/L), and sufficiency (≥0.70 μmol/L); neonatal VitA relative deficiency was further defined as cord blood plasma retinol concentration lower than the 10th percentile. VitA placental transport ratio was defined as retinol concentration in the neonates divided by that in pregnant women. Multivariable fractional polynomials (MFP) model and Pearson correlation were used to study the dose-response relationship between maternal and neonatal plasma VitA levels, Logistic regression model to estimate the effect of maternal VitA nutritional status on neonatal VitA deficiency, and MFP model and Spearman correlation to describe the relationship between maternal VitA level and VitA placental transport ratio.

RESULTS

The average retinol concentration of the pregnant women was (1.15±0.30) μmol/L, and the prevalence of VitA deficiency and marginal deficiency were 4.5% and 37.8%, respectively. Average retinol concentration of the neonates was (0.78±0.13) μmol/L, and no neonates were VitA deficiency, 28.2% of the neonates were marginal deficiency. After multivariable adjustment, the VitA level of the neonates was positively and linearly related to maternal VitA level (pm=1, P<0.05), with the corresponding Pearson correlation coefficient of 0.13 (P<0.01). As compared with the women with sufficient VitA, those with VitA deficiency (crude OR=2.20, 95%CI:1.04-4.66) and marginal deficiency (crude OR=1.43, 95%CI:1.01-2.02) had higher risks to deliver neonates with VitA marginal deficiency; while the risks turned to be non-significant after multivariable adjustment. The pregnant women with VitA deficiency had higher risk to deliver neonates with relative VitA deficiency before and after multivariable adjustment (crude OR=3.02, 95%CI:1.21-7.50; adjusted OR=2.76, 95%CI:1.05-7.22). The maternal VitA level was negatively and non-linearly correlated with placental transport ratio (pm= -0.5, P<0.05), with corresponding adjusted Spearman correlation coefficient of -0.82 (P<0.001).

CONCLUSION

There was a positive linear dose-response relationship between VitA levels of newborns and pregnant women in third trimester, indicating that neonatal VitA storing levels at birth was affected by maternal VitA nutritional status.

Brazilian cohorts with potential for life-course studies: a scoping review

OBJECTIVE To identify the Brazilian cohorts that started either in the prenatal period or at birth, to describe their characteristics and the explored variables, and to map the cohorts with potential for studies on early determinants on health and the risk of falling ill on later stages of the life cycle. METHODS A scoping review was carried out. The articles were searched in the electronic databases PubMed and Virtual Health Library (VHL). The descriptors used were [((("Child" OR "Child, Preschool" OR "Infant" OR "Infant, Newborn") AND (Cohort Studies" OR "Longitudinal Studies")) AND "Brazil")]. The inclusion criteria were Brazilian cohorts that started the baseline in the prenatal period or at birth and with at least two follow-ups with the participants. In order to meet the concept of LCE, we excluded those cohorts whose follow-ups were restricted to the first year of life, as well as those that did not address biological, behavioral and psychosocial aspects, and cohorts with data collection of a single stage of the life cycle. RESULTS The search step identified 5,010 articles. Eighteen cohorts were selected for descriptive synthesis. The median number of baseline participants was 2,000 individuals and the median age at the last follow-up was 9 years. Sample loss at the last follow-up ranged from 9.2 to 87.5%. Most cohorts monitored two phases of the life cycle (the perinatal period and childhood). The Southern region had the highest number of cohorts. The main variables collected were sociodemographic and environmental aspects of the family, morbidity aspects, nutritional practices and lifestyle. CONCLUSIONS We recommend the continuity of these cohorts, the approach to different social contexts and the performance of follow-ups with participants in different phases of the life cycle for the strengthening and expansion of life course epidemiology analyses in Brazil.

Cohort profile: the Maternal and Child Health and Nutrition in Acre, Brazil, birth cohort study (MINA-Brazil)

PURPOSE

Maternal and Child Health and Nutrition in Acre, Brazil (MINA-Brazil) is a longitudinal, prospective population-based birth cohort, set-up to understand the effects of early environmental exposures and maternal lifestyle choices on growth and development of the Amazonian children.

PARTICIPANTS

Mother-baby pairs (n=1246) were enrolled at delivery from July 2015 to June 2016 in Cruzeiro do Sul, Acre, Brazil. Mothers of 43.7% of the cohort were recruited in the study during pregnancy from February 2015 to January 2016. Study visits took place during pregnancy, delivery, at 1 month, 6 months, 1 year and 2 years after delivery. In addition to clinical and epidemiological data, samples collected by the MINA-Brazil study include plasma, serum and extracted DNA from blood and faeces, which are stored in a biobank.

FINDINGS TO DATE

Key baseline reports found a high prevalence of gestational night blindness (11.5%; 95% CI 9.97% to 13.25%) and maternal anaemia (39.4%; 95% CI 36.84% to 41.95%) at delivery. Antenatal malaria episodes (74.6% of Plasmodium vivax) were diagnosed in 8.0% of the women and were associated with an average reduction in birth weight z-scores of 0.35 (95% CI 0.14 to 0.57) and in birth length z-scores of 0.31 (95% CI 0.08 to 0.54), compared with malaria-free pregnancies. At 2-year follow-up, data collection strategies combined telephone calls, WhatsApp, social media community and home visits to minimise losses of follow-up (retention rate of 79.5%).

FUTURE PLANS

A 5-year follow-up visit is planned in 2021 with similar interviews and biospecimens collection. The findings from this prospective cohort will provide novel insights into the roles of prenatal and postnatal factors in determining early childhood development in an Amazonian population.