Targeting strategies for balanced energy and protein (BEP) supplementation in pregnancy: study protocol for the TARGET-BEP cluster-randomized controlled trial in rural Bangladesh.

BACKGROUND: The World Health Organization (WHO) recommends balanced energy and protein (BEP) supplementation be provided to all pregnant women living in undernourished populations, usually defined as having a prevalence > 20% of underweight women, to reduce the risk of stillbirths and small-for-gestational-age neonates. Few geographies meet this threshold, however, and a large proportion of undernourished women and those with inadequate gestational weight gain could miss benefiting from BEP. This study compares the effectiveness of individual targeting approaches for supplementation with micronutrient-fortified BEP vs. multiple micronutrient supplements (MMS) alone as control in pregnancy in improving birth outcomes. METHODS: The TARGET-BEP study is a four-arm, cluster-randomized controlled trial conducted in rural northwestern Bangladesh. Eligible participants are married women aged 15-35 years old identified early in pregnancy using a community-wide, monthly, urine-test-based pregnancy detection system. Beginning at 12-14 weeks of gestation, women in the study area comprising 240 predefined sectors are randomly assigned to one of four intervention arms, with sector serving as the unit of randomization. The interventions involving daily supplementation through end of pregnancy are as follows: (1) MMS (control); (2) BEP; (3) targeted BEP for those with pre-pregnancy body mass index (BMI) < 18.5 kg/m2 and MMS for others; (4) targeted BEP for those with pre-pregnancy BMI < 18.5 kg/m2, MMS for others, and women with inadequate gestational weight gain switched from MMS to BEP until the end of pregnancy. Primary outcomes include birth weight, low birth weight (< 2500 g), and small for gestational age, defined using the 10th percentile of the INTERGROWTH-21st reference, for live-born infants measured within 72 h of birth. Project-hired local female staff visit pregnant women monthly to deliver the assigned supplements, monitor adherence biweekly, and assess weight regularly during pregnancy. Trained data collectors conduct pregnancy outcome assessment and measure newborn anthropometry in the facility or home depending on the place of birth. DISCUSSION: This study will assess the effectiveness of targeted balanced energy and protein supplementation to improve birth outcomes among pregnant women in rural Bangladesh and similar settings. TRIAL REGISTRATION: ClinicalTrials.gov NCT05576207. Registered on October 5th, 2022.

Pharmacological Interventions for the Treatment and Control of Shivering in Adult Patients Undergoing Elective Surgery Under Regional Anaesthesia: A Systematic Review and Meta-Analysis.

Intraoperative shivering is quite common after regional anaesthesia, which not only increases the total body oxygen requirement but also causes discomfort to the patients. The aim of this systematic review is to determine the effectiveness of pharmacological agents administered intra-operatively for treating shivering in adult patients who are undergoing elective surgery under regional (i.e., central neuraxial) anaesthesia so that an optimal choice of an agent can be recommended for clinical application. A literature search was carried out using PubMed, Cochrane Library, CINAHL databases, and hand searches to identify relevant studies. After literature screening and information extraction, a systematic review was performed. Meta-analysis was performed for the primary outcome. The primary outcome was to evaluate the effectiveness of pharmacological agents used for the treatment and control of intraoperative shivering and the time taken to control shivering. The secondary outcome includes recurrence of shivering after pharmacological intervention and identification of common adverse effects related to them. In total, 10 studies (791 patients) were included. Common interventions were opioids, central α2 receptor agonist, and few other medications like magnesium sulfate, ondansetron, nefopam, and amitriptyline. Tramadol and dexmedetomidine were the most frequently documented drugs compared with other drugs to resolve shivering. The most effective drug with approximately 100% response rate was dexmedetomidine with the dose of 0.5 µg kg-1 intravenously given just after the appearance of shivering. Studies showed that tramadol is also an effective drug used to control shivering in most patients, and its effect is comparable with the pethidine.

Anaesthetic management of patients undergoing deep brain simulation: A retrospective review of 8 cases from a tertiary care center of Pakistan.

OBJECTIVES: To review anaesthesia related outcome, perioperative complications and overall length of stay (LOS) in hospital for patients who had deep brain stimulation (DBS). METHODS: The study was retrospective review of patients medical records diagnosed with Parkinson disease (PD) and underwent DBS at The Aga Khan University Hospital, Karachi from 2017-2019. Data was reviewed from file notes and patient chart and recorded on predesigned Performa. Frequency and percentages were used to present the data. RESULTS: All patients were anaesthetized using Sleep-Awake-Sleep technique (SAS). Dexmedetomidine was mainly used for conscious sedation. Bispectral index monitor (BIS) was used to monitor the depth of sedation, and kept between 70-85 during sedative phase. All patients had successful intraoperative neurological monitoring, stimulation, and placement of electrodes. Total duration of anesthesia varied significantly in between the patients. Maximum duration was 600 minutes. None of our patient had any intraoperative event related to anaesthetic management. Overall five patients had some adverse events during ward stay. Mean LOS in hospital was four days. CONCLUSION: Anaesthetic management of DBS is well-tolerated. It requires dedicated team. The SAS technique is excellent for intraoperative neurophysiological monitoring. Careful selection of sedative agents and monitoring depth of anaesthesia using BIS would be beneficial in terms of improving related outcomes.

Utilization of awake craniotomy for supra-tentorial tumor resection during pregnancy: A technique useful for fetal-maternal wellbeing.

Meningioma is the benign tumor that can also occurs during pregnancy. We are reporting a case of 29 years, 13th weeks pregnant lady, who underwent supratentorial craniotomy using awake through out approach. The case report highlights the challenges we faced during anaesthetic management, which includes psychological preparation, institution of scalp block and successful neurological monitoring. Technique proven to be useful considering pregnancy related physiological and tumor related pathological changes, the impact of which lies directly on maternal & fetal wellbeing.

Anaesthetic Management of Cerebral Arterio-venous Malformation Excision Using Awake Craniotomy: Initial Experience of Two Cases.

This case series summarises the successful management of two cases with cerebral arterio-venous malformation (AVM). In first patient, it was located superficially in right frontal cortex, while the second one had this in left parieto-temporal region. Both were excised successfully using awake craniotomy. The patients had their assessment and psychological preparation by neuro-anesthetist and neurosurgeon. Along with the routine monitoring, invasive arterial line, and bispectral index monitoring was used to monitor the sedative effect of propofol. Intraoperative analgesia was provided using scalp block. The anaesthetic management was helpful in facilitating intraoperative neurological monitoring using verbal and motor responses. Patients remained pain-free and hemodynamically stable during resection phase. The postoperative period showed adequate pain control, decreased postoperative nausea/vomiting and shorter length of stay in the hospital. Both patients had 100% obliteration of AVM confirmed via cerebral angiography.

Associations of Arsenic Exposure With Telomere Length and Naïve T Cells in Childhood-A Birth Cohort Study.

There is limited knowledge of association between arsenic exposure and telomere length (TL) and signal joint T-cell receptor excision circle (sjTREC) that are potential biomarkers of immune senescence and disease susceptibility. We aimed to clarify whether long-term inorganic arsenic exposure influences TL and sjTRECs in childhood. Children born in a longitudinal mother-child cohort were followed-up at 4.5 (n = 275) and 9 years (n = 351) of age. Arsenic exposure was assessed by metabolite concentrations in urine (U-As) from mothers at gestational week 8 (prenatal) and their children at 4.5 and 9 years. TL and sjTRECs were determined in blood cells using quantitative PCR. The oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) in plasma was measured by ELISA. In multivariable-adjusted spline regression analyses, both prenatal and childhood arsenic exposure above U-As of 45 µg/l were significantly inversely associated with TL and sjTRECs at 9 years. Fraction of monomethylarsonic acid (MMA) above spline knot 7% were significantly inversely associated with both TL and sjTRECs reflecting increased toxicity due to less-efficient arsenic metabolism in 9--year-old children. Prenatal and childhood arsenic exposure were positively associated with 8-OHdG at 9 years which in turn was inversely associated with sjTRECs at 9 years. However, adjustment with 8-OHdG did not change the estimates of the association of U-As with sjTRECs reflecting little contribution from 8-OHdG-induced oxidative stress. Our findings suggest that chronic arsenic exposure from early life can result in TL attrition and lower production of naïve T cells potentially leading to immunosenescence and immunodeficiency.

Factors affecting reintubations after cardiac and thoracic surgeries in cardiac intensive care unit of a tertiary care hospital.

BACKGROUND: Reintubation and readmission after cardiothoracic surgeries are not uncommon, and its reasons are multifactorial. The study goal was to identify the factors that contribute reintubation after cardiac and thoracic surgery in tertiary care hospital and to compare the outcome with international benchmark. METHODOLOGY: A prospective, observational study was planned in Cardiac Intensive Care Unit (CICU). The study included all those patients who required readmission in CICU due to endotracheal intubation following cardiac and thoracic surgeries. The study was conducted from January to December 2016. The primary focus was to identify the reasons for reintubation within 72 h of extubation after CICU discharge and its association with outcome. RESULTS: Out of 750 patients who shifted out from CICU following successful extubation, only 32 were readmitted and among them in 25 patients (3.33%) were reintubated and their reasons reintubation were noted. Patients underwent a coronary artery bypass grafting (CABG) with valve replacement had a higher incidence of reintubation 3/39 (7.69%) when compared with CABG 13/517 (2.51%) and 4/135 (2.96%) valve procedure alone. Single cause of endotracheal reintubation was observed in 7 patients (28%), in which 5 patients (20%) had respiratory and 2 patients had (8%) cardiac reason while 18 patients (72%) were observed with multisystem involvement, in which 7 patients (28%) had both respiratory and cardiovascular causes, and 2 (8%) had both respiratory and neurological causes. More than 70% cause of endotracheal reintubation was both respiratory and cardiovascular. The CICU stay after reintubations was 12.88 ± 16.88 days and the hospital stay prolonged to 23.84 ± 21.61 days. CONCLUSION: Reasons of reintubation were mainly respiratory and cardiac. The rate of reintubations is high when multisystem involvement is there. CICU, hospital stay, and mortality are increases after reintubation.

SRSF1 suppresses selection of intron-distal 5' splice site of DOK7 intron 4 to generate functional full-length Dok-7 protein.

Dok-7 is a non-catalytic adaptor protein that facilitates agrin-induced clustering of acetylcholine receptors (AChR) at the neuromuscular junction. Alternative selection of 5' splice sites (SSs) of DOK7 intron 4 generates canonical and frame-shifted transcripts. We found that the canonical full-length Dok-7 enhanced AChR clustering, whereas the truncated Dok-7 did not. We identified a splicing cis-element close to the 3' end of exon 4 by block-scanning mutagenesis. RNA affinity purification and mass spectrometry revealed that SRSF1 binds to the cis-element. Knocking down of SRSF1 enhanced selection of the intron-distal 5' SS of DOK7 intron 4, whereas MS2-mediated artificial tethering of SRSF1 to the identified cis-element suppressed it. Isolation of an early spliceosomal complex revealed that SRSF1 inhibited association of U1 snRNP to the intron-distal 5' SS, and rather enhanced association of U1 snRNP to the intron-proximal 5' SS, which led to upregulation of the canonical DOK7 transcript. Integrated global analysis of CLIP-seq and RNA-seq also indicated that binding of SRSF1 immediately upstream to two competing 5' SSs suppresses selection of the intron-distal 5' SS in hundreds of human genes. We demonstrate that SRSF1 critically regulates alternative selection of adjacently placed 5' SSs by modulating binding of U1 snRNP.

Incidence and pattern of Thrombocytopenia in cardiac surgery patients.

OBJECTIVE: To observe the incidence and pattern of thrombocytopenia in cardiac surgery patients. METHODS: This prospective, cohort study was conducted at the Aga Khan University Hospital, Karachi, from November 2014 to April 2015, and comprised adult cardiac patients. Patients with platelet count less than 150,000 x 109/L, history of malignancy, immune thrombocytopenic purpura and on chemo or radiotherapy were excluded. All information including demographics, platelet count, heparin doses, total cardiopulmonary bypass time, cross-clamp time, blood products transfused, any thromboembolic complication and the presence of infection were recorded on a pre-designed proforma. SPSS 19 was used for data analysis.. RESULTS: Of the 177 patients, 130(73.4%) were males and 47(26.6%) were females. The overall mean age was 59.21±10.99 years. Thrombocytopenia was observed in 167(94.4%) patients. Of them, platelet count dropped below 50% in 71(42.5%) patients, 30-50% in 68(40.7%) patients and 20-30% in 28(16.8%) from the baseline value. Regarding pattern of thrombocytopenia, maximum drop in platelet count was noticed on 2nd and 3rd day of surgery. Furthermore, 9(5.3%) patients developed severe thrombocytopenia (<50,000 x 109/L). CONCLUSIONS: The incidence of thrombocytopenia and its severity after cardiac surgery was very high in our study population when compared with western population.

Humoral Immunity in Arsenic-Exposed Children in Rural Bangladesh: Total Immunoglobulins and Vaccine-Specific Antibodies.

BACKGROUND: Early-life arsenic exposure has been associated with reduced cell-mediated immunity, but little is known about its effects on humoral immunity. OBJECTIVE: We evaluated whether prenatal and childhood arsenic exposure was associated with humoral immune function in school-aged children. METHODS: Children born in a prospective mother­child cohort in rural Bangladesh were immunized with measles, mumps, and rubella (MMR) vaccines at 9 years of age (n=525). Arsenic exposure was assessed in urine (U-As), from mothers during pregnancy and their children at 4.5 and 9 years of age. Total IgG (tIgG), tIgE, tIgA, and MMR-specific IgG concentrations were measured in plasma using immunoassays. RESULTS: Arsenic exposure was positively associated with child tIgG and tIgE, but not tIgA. The association with tIgG was mainly apparent in boys (p for interaction=0.055), in whom each doubling of maternal U-As was related to an increase in tIgG by 28 mg/dL. The associations of U-As at 9 years with tIgG and tIgE were evident in underweight children (p for interaction <0.032). Childhood arsenic exposure tended to impair mumps-specific vaccine response, although the evaluation was complicated by high preimmunization titers. Postimmunization mumps­specific IgG titers tended to decrease with increasing U-As at 4.5 and 9 years of age [regression coefficient (ß)=−0.16; 95% confidence interval (CI): −0.33, 0.01; p=0.064 and ß=−0.12; 95% CI: −0.27, −0.029; p=0.113, respectively) in 25% children with the lowest preexisting mumps-specific IgG titers. CONCLUSIONS: Arsenic exposure increased tIgG and tIgE in plasma, and tended to decrease mumps-specific IgG in children at 9 years of age. https://doi.org/10.1289/EHP318.

Vitamin B12 supplementation during pregnancy and postpartum improves B12 status of both mothers and infants but vaccine response in mothers only: a randomized clinical trial in Bangladesh.

PURPOSE: Poor vitamin B12 (B12) status is associated with adverse outcomes in pregnancy and infancy. Little is known about effects of B12 supplementation on immune function. The present study aimed to evaluate effects of pre- and postnatal B12 supplementation on biomarkers of B12 status and vaccine-specific responses in mothers and infants. METHOD: In a blinded, placebo-controlled trial, Bangladeshi women (n = 68, age 18-35 years, hemoglobin <110 g/L, 11-14 weeks pregnant) were randomized to receive 250 µg/day B12 or a placebo throughout pregnancy and 3-month postpartum along with 60 mg iron + 400 µg folate. Women were immunized with pandemic influenza A (H1N1) vaccine at 26- to 28-week gestation. Blood from mothers (baseline, 72-h post-delivery, 3-month postpartum), newborns and infants (3-month) was analyzed for hemoglobin, B12, methylmalonic acid (MMA), total homocysteine (tHcy), ferritin and serum transferrin receptor, C-reactive protein (CRP) and alpha-1-acid glycoprotein (AGP). Vitamin B12 was also assessed in breast milk. H1N1-specific antibodies were determined in plasma and colostrum/breast milk. RESULTS: At baseline, 26% women were B12 deficient (<150 pmol/L), 40% had marginal status (150-220 pmol/L), 43% had elevated MMA (>271 nmol/L), and 31% had elevated tHcy (>10 µmol/L). Supplementation increased B12 in plasma, colostrums and breast milk (p < 0.05) and lowered MMA in neonates, mothers and infants at 3 months (p < 0.05). B12 supplementation significantly increased H1N1-specific IgA responses in plasma and colostrums in mothers and reduced proportion of infants with elevated AGP and CRP compared with placebo. CONCLUSION: Supplementation with 250 µg/day B12 during pregnancy and lactation substantially improved maternal, infant and breast milk B12 status. Maternal supplementation improved H1N1 vaccine-specific responses in mothers only and may alleviate inflammatory responses in infants.

SRSF1 and hnRNP H antagonistically regulate splicing of COLQ exon 16 in a congenital myasthenic syndrome.

The catalytic subunits of acetylcholinesterase (AChE) are anchored in the basal lamina of the neuromuscular junction using a collagen-like tail subunit (ColQ) encoded by COLQ. Mutations in COLQ cause endplate AChE deficiency. An A-to-G mutation predicting p.E415G in COLQ exon 16 identified in a patient with endplate AChE deficiency causes exclusive skipping of exon 16. RNA affinity purification, mass spectrometry, and siRNA-mediated gene knocking down disclosed that the mutation disrupts binding of a splicing-enhancing RNA-binding protein, SRSF1, and de novo gains binding of a splicing-suppressing RNA-binding protein, hnRNP H. MS2-mediated artificial tethering of each factor demonstrated that SRSF1 and hnRNP H antagonistically modulate splicing by binding exclusively to the target in exon 16. Further analyses with artificial mutants revealed that SRSF1 is able to bind to degenerative binding motifs, whereas hnRNP H strictly requires an uninterrupted stretch of poly(G). The mutation compromised splicing of the downstream intron. Isolation of early spliceosome complex revealed that the mutation impairs binding of U1-70K (snRNP70) to the downstream 5' splice site. Global splicing analysis with RNA-seq revealed that exons carrying the hnRNP H-binding GGGGG motif are predisposed to be skipped compared to those carrying the SRSF1-binding GGAGG motif in both human and mouse brains.

Right ventricular perforation: a rare complication of pulmonary artery catheterization.

A 70 years old male underwent Coronary Artery Bypass and Graft (CABG) surgery. After induction, a Pulmonary Artery Catheter (PAC) was inserted via right IJV with some difficulty in achieving PA tracing. During distal RCA anastomosis, surgeon noticed PAC tip coming out of Right Ventricular (RV) surface. Resistance was felt on trying to pull PAC, so it was left there. Cardiac surgeon then opened the Right Atrium (RA) and pulled out the catheter. Multiple attempts during insertion of PA catheter should always raise the suspicion of PAC tip slipping back into the RV. It should be closely monitored during surgery and communicated to the surgeon.

Safety profile of fast-track extubation in pediatric congenital heart disease surgery patients in a tertiary care hospital of a developing country: An observational prospective study.

BACKGROUND AND AIMS: Early extubation after cardiac operations is an important aspect of fast-track cardiac anesthesia. In order to reduce or eliminate the adverse effects of prolonged ventilation in pediatric congenital heart disease (CHD) surgical patients, the concept of early extubation has been analyzed at our tertiary care hospital. The current study was carried out to record the data to validate the importance and safety of fast-track extubation (FTE) with evidence. MATERIALS AND METHODS: A total of 71 patients, including male and female aged 6 months to 18 years belonging to risk adjustment for congenital heart surgery-1 category 1, 2, and 3 were included in this study. All patients were anesthetized with a standardized technique and surgery performed by the same surgeon. At the end of operation, the included patients were assessed for FTE and standard extubation criteria were used for decision making. RESULTS: Of the total 71 patients included in the study, 26 patients (36.62%) were extubated in the operating room, 29 (40.85%) were extubated within 6 h of arrival in cardiovascular intensive care unit and 16 (22.54%) were unable to get extubated within 6 h due to multiple reasons. Hence, overall success rate was 77.47%. The reasons for delayed extubation were significant bleeding in 5 (31.3%) cases, hemodynamic instability (low cardiac output syndrome) in 4 (25%) cases, respiratory complication in 2 (12.5%), bleeding plus hemodynamic instability in 2 (12.5) cases, hemodynamic instability, and respiratory complication in 2 (12.5%) cases and triad of hemodynamic instability, bleeding and respiratory complication in 1 (6.5%) case. There was no reintubation in the FTE cases. CONCLUSION: On the basis of the current study results, it is recommended to use FTE in pediatric CHD surgical patients safely with multidisciplinary approach.

Comparison of efficacy of ondansetron and dexamethasone combination and ondansetron alone in preventing postoperative nausea and vomiting after laparoscopic cholecystectomy.

OBJECTIVE: To compare the efficacy of ondansetron alone and combination of ondansetron and dexamethasone in preventing post-operative nausea and vomiting in patients undergoing laparoscopic cholecystectomy. METHODS: The randomised control trial was conducted from April 23 to August 22, 2009, at the Liaquat National Hospital, Karachi, and comprised 100 American Society of Anaesthesiology I and II patients undergoing laparoscopic cholecystectomy. Half of the subjects comprised Group A and received ondansetron alone, while Group B received combination of ondansetron and dexamethasone. They were randomised by opaque envelope method. Group A received ondansetron 4 mg while Group B received ondansetron 4 mg with dexamethasone 8 mg, 1 minute before induction. Post-operatively patients were observed for six hours for any episode of nausea or vomiting, or whether the patients required any rescue anti emetic. SPSS 19 was used for statistical analysis. RESULTS: Patients receiving ondansetron alone showed 14 (28%) with incidence of nausea or vomiting while the other group showed 6 (12%). This difference was statistically significant (p < 0.046). CONCLUSION: Combination of ondansetron and dexamethasone was more efficacious compared to ondansetron alone in the prevention of postoperative nausea and vomiting in patients undergoing laparoscopic cholecystectomy.

Arsenic exposure affects plasma insulin-like growth factor 1 (IGF-1) in children in rural Bangladesh.

BACKGROUND: Exposure to inorganic arsenic (As) through drinking water during pregnancy is associated with lower birth size and child growth. The aim of the study was to assess the effects of As exposure on child growth parameters to evaluate causal associations. METHODOLOGY/FINDINGS: Children born in a longitudinal mother-child cohort in rural Bangladesh were studied at 4.5 years (n=640) as well as at birth (n=134). Exposure to arsenic was assessed by concurrent and prenatal (maternal) urinary concentrations of arsenic metabolites (U-As). Associations with plasma concentrations of insulin-like growth factor 1 (IGF-1), calcium (Ca), vitamin D (Vit-D), bone-specific alkaline phosphatase (B-ALP), intact parathyroid hormone (iPTH), and phosphate (PO4) were evaluated by linear regression analysis, adjusted for socioeconomic factor, parity and child sex. Child U-As (per 10 µg/L) was significantly inversely associated with concurrent plasma IGF-1 (ß=-0.27; 95% confidence interval: -0.50, -0.0042) at 4.5 years. The effect was more obvious in girls (ß=-0.29; -0.59, 0.021) than in boys, and particularly in girls with adequate height (ß=-0.491; -0.97, -0.02) or weight (ß=-0.47; 0.97, 0.01). Maternal U-As was inversely associated with child IGF-1 at birth (r=-0.254, P=0.003), but not at 4.5 years. There was a tendency of positive association between U-As and plasma PO4 in stunted boys (ß=0.27; 0.089, 0.46). When stratified by % monomethylarsonic acid (MMA, arsenic metabolite) (median split at 9.7%), a much stronger inverse association between U-As and IGF-1 in the girls (ß=-0.41; -0.77, -0.03) was obtained above the median split. CONCLUSION: The results suggest that As-related growth impairment in children is mediated, at least partly, through suppressed IGF-1 levels.

Transatrial access for left atrial pressure (LAP) monitoring line placement in arterial switch operation (ASO) in neonates.

Left Atrial pressure monitoring is a useful and accurate method to guide Left ventricle filling in the patients who undergo Arterial switch operation for transposition of great arteries. We have used a different technique in three TGA patients for LA pressure monitoring line placement. After cleaning and draping,right internal jugular vein (rt IJV) located through 22G venous cannula, guide wire was put in followed by sliding the 22G x 8cm vygon arterial catheter over the guide wire into the right atrium that was directed transatrially into LA by the operating surgeon during atrial septum repair. The catheter was secured by silk on the neck and dressed with transparent dressing and was kept for a period of 48-72 hrs. LA pressure monitoring is helpful in anticipating LV dysfunction in ASO.

In utero arsenic exposure is associated with impaired thymic function in newborns possibly via oxidative stress and apoptosis.

Prenatal arsenic exposure is associated with increased infant morbidity and reduced thymus size, indicating arsenic-related developmental immunotoxicity. We aimed to evaluate effects of prenatal arsenic exposure on thymic function at birth and related mechanisms of action. In a Bangladeshi cohort, arsenic was measured in urine (U-As, gestational week (GW) 8 and 30) and blood (B-As, GW14) in 130 women. Child thymic index was measured by sonography at birth and thymic function by signal-joint T-cell receptor-rearrangement excision circles (sjTRECs) in cord blood mononuclear cells (CBMC). In a subsample (n = 44), sjTRECs content in isolated CD4(+) and CD8(+) T cells, expression of oxidative-stress defense and apoptosis-related genes in CBMC, arsenic concentrations (urine, placenta, and cord blood), and oxidative stress markers in placenta and cord blood were measured. In multivariable-adjusted regression, ln U-As (GW8) was inversely associated with ln sjTRECs in CBMC (B = -0.25; 95% confidence interval [CI] -0.48 to -0.01). Using multivariable-adjusted spline regression, ln U-As (GW30) and ln B-As (GW14) were inversely associated with ln sjTRECs in CBMC (B = -0.53; 95% CI -0.93 to -0.13 and B = -1.27; 95% CI -1.89 to -0.66, respectively) below spline knots at U-As 150 µg/l and B-As 6 µg/kg. Similar inverse associations were observed in separated CD4(+) and CD8(+) T cells. Arsenic was positively associated with 8-hydroxy-2'-deoxyguanosine in cord blood (B = 0.097; 95% CI 0.05 to 0.13), which was inversely associated with sjTRECs in CD4(+) and CD8(+) T cells. In conclusion, prenatal arsenic exposure was associated with reduced thymic function, possibly via induction of oxidative stress and apoptosis, suggesting subsequent immunosuppression in childhood.