Cohort profile: The Pregnancy, Arsenic, and Immune Response (PAIR) Study, a longitudinal pregnancy and birth cohort in rural northern Bangladesh

ABSTRACT Purpose Arsenic exposure and micronutrient deficiencies may alter immune reactivity to influenza vaccination in pregnant women, transplacental transfer of maternal antibodies to the fetus, and maternal and infant acute morbidity. The Pregnancy, Arsenic, and Immune Response (PAIR) Study is a longitudinal pregnancy and birth cohort designed to assess whether arsenic exposure and micronutrient deficiencies alter maternal or newborn immunity and acute morbidity following maternal seasonal influenza vaccination during pregnancy. Participants We enrolled 784 pregnant women in rural Gaibandha District in northern Bangladesh between October 2018 and March 2019. Women received a quadrivalent seasonal inactivated influenza vaccine at enrollment in the late first or early second trimester between 11 and 17 weeks of gestational age. Follow-up included up to 13 visits between enrollment and three months postpartum as well as weekly telephone surveillance to ascertain influenza-like illness and other acute morbidity symptoms in women and infants. Tube well drinking water and urine specimens were collected to assess arsenic exposure. Of 784 women who enrolled, 736 (93.9%) delivered live births and 551 (70.3%) completed follow-up visit to three months postpartum. Findings to Date Arsenic was ≥0.02 µg/L in 97.9% of water specimens collected from participants at enrollment. The medians (interquartile ranges) of water and urinary arsenic were 5.1 (0.5-25.1) µg/L and 33.1 (19.6-56.5) µg/L, respectively. Water and urinary arsenic were strongly correlated (Spearman’s ρ=0.72) among women with water arsenic ≥ median but weakly correlated (ρ=0.18) among women with water arsenic < median. Future Plans The PAIR Study is well positioned to examine the effects of low-moderate arsenic exposure and micronutrient deficiencies on immune outcomes in women and infants. Registration NCT03930017