Background Preterm birth (PTB) and its complications are important public health problems. Its aetiology is multifactorial and involves both modifiable and non-modifiable factors. Among the modifiable risk factors, micronutrient deficiencies, including maternal folate deficiency, are increasingly being studied in PTB. In this study, we estimated the prevalence of folate deficiency during pregnancy and examined its association with PTB among rural Bangladeshi women. Methods We conducted a nested case-control study using data from a population-based cohort of 3000 pregnant women who were enrolled between 8 and 19 weeks of gestation following ultrasound confirmation of gestational age. Sociodemographic, epidemiologic, clinical, and pregnancy outcomes data were collected through home visits, while blood samples were collected at enrolment and 24-28 weeks of gestation during pregnancy. We included all women who delivered preterm (defined as live births <37 weeks of gestation) as cases (n = 235) and a random sample of women having a term birth as controls (n = 658). The main exposure was folate concentrations in maternal serum during 24-28 weeks of pregnancy. We categorised women into folate deficient (= 3 ng/mL). We then performed multivariable logistic regression analysis to examine the association between maternal folate levels and PTB, adjusting for relevant covariates. Results Thirty-eight per cent of the enrolled pregnant women were folate deficient. Maternal serum folate deficiency was significantly associated with PTB (adjusted OR (aOR) = 1.73; 95% confidence interval (CI) = 1.27-2.36). The risk of PTB was also higher among women who were of short stature (aOR = 1.83; 95% CI = 1.27-2.63), primiparous (aOR = 1.60; 95% CI = 1.15-2.22), and had exposure to passive smoking (aOR = 1.54; 95% CI = 1.02-2.31). Conclusions The prevalence of folate deficiency was high among pregnant women in rural Bangladesh, and folate deficiency was significantly associated with an increased risk of preterm birth.

The purpose of this study was to determine the seropositivity of circulating viral pathogens and their association with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seropositivity. In a cross-sectional design, inhabitants (aged 10–60 years) of the slum and surrounding non-slum areas of Dhaka and Chattogram Metropolitan cities in Bangladesh were enrolled from October 2020 to February 2021. Antibodies to SARS-CoV-2, influenza B, parainfluenza, respiratory syncytial virus (RSV), human coronavirus HKU1 (HCoV-HKU1), dengue and chikungunya viruses were determined in plasma. The association of SARS-CoV-2 seropositivity with seropositivity to other viruses was assessed using the multi-variate logistic regression model. Seroprevalence of SARS-CoV-2, influenza B, RSV, dengue, chikungunya, HCoV-HKU1 and the parainfluenza virus were 68.3%, 98%, 50.0%, 16.5%, 15.5%, 3.36% and 0.0%, respectively. Individuals seropositive for RSV had lower odds (OR = 0.60; 95% CI= 0.49, 0.73) of SARS-CoV-2 seropositivity compared to RSV-seronegative individuals. Conversely, higher odds of SARS-CoV-2 seropositivity were observed in participants seropositive for dengue (OR= 1.73; 95% CI = 1.14, 2.66, only in slum) or chikungunya (OR = 1.48; 95% CI = 1.11, 1.95) compared to their seronegative counterparts. The study findings indicated that exposure to vector-borne virus dengue or chikungunya enhance, while antibodies to respiratory virus RSV decrease, the serological response to SARS-CoV-2.

Probiotics may enhance host iron bioavailability, offering a strategy to address iron deficiency. Fecal iron may be a useful noninvasive biomarker of such effects in infants. To examine the use of fecal iron quantification in a randomized placebo-controlled trial (RCT) of neonatal administration of Lactiplantibacillus plantarum ATCC 202195 (LP202195), with or without fructooligosaccharide (FOS), in Dhaka, Bangladesh. Fecal iron quantification using atomic absorption spectrometry (AAS) was optimized using standards and reference materials, and pilot-tested using pooled stool aliquots (n = 32) from an observational cohort of young infants in Bangladesh (aged 0-64 days). The optimized AAS assay was then applied to individual stool samples collected at 14 days of age (n = 307) in a RCT in which newborns aged 0-4 days were randomly allocated to one of five groups: placebo, 1- or 7-day regimens of LP202195, with or without FOS. Serum ferritin was measured at 2 months postnatal age (n = 251). Effects of the 1- and 7-day LP202195 regimens were estimated using linear regression and expressed as mean percent differences relative to placebo, with 95% confidence intervals (95% CI). The optimized AAS fecal iron assay had acceptable accuracy (91%-99%), precision (within- and between-run coefficients of variation 0.05 for all). Similarly, there were no effects of LP202195 on serum ferritin at 2 months of age (P > 0.05 for all). Fecal iron quantification by AAS was valid and feasibly implemented in a trial of neonatal administration of L. plantarum ATCC 202195. However, the assay is resource-intensive and may not be more informative than conventional measures of iron status when studying the effects of probiotics/synbiotics on iron bioavailability. ClinicalTrials.gov identifier: NCT05180201.