Trajetórias de hemoglobina total durante a gravidez e pós-parto e seus fatores associados entre adolescentes e adultas da região do Trairi: estudo longitudinal

Abstract

Introduction: During pregnancy, there is intense anabolic activity that increases demand for hemoglobin to ensure adequate fetal development. Hemoglobin levels are expected to reduce from the first to third trimester of pregnancy and return to prepregnancy levels in the post-partum period. However, little is known about the variation between adolescent and adult pregnant women and their associated factors. Objective: The aim of this study is to evaluate the trajectories of total hemoglobin (THB) variation during pregnancy and postpartum and its associated factors among low-income adolescents and adults. Methods: This is an observational, longitudinal study that is part of the pilot project Adolescence and Motherhood Research (AMOR). The data was collected between July 2017 and January 2019 in five municipalities of the Trairi region of the Rio Grande do Norte State, Brazil, with a sample consisting of 50 pregnant adolescents and 50 adults in their first pregnancy. The participants’ THB levels were monitored in three periods: up to 16 weeks of gestation, in the third trimester of gestation, and between 4 and 6 weeks postpartum. Covariates included socioeconomic characteristics, weight and height, self-perceived health status, number of prenatal appointments, pregnancy planning, food security, age at menarche, type of delivery and breastfeeding. Mixed linear models were used to evaluate the trajectories of variation of THB in both groups, in the total sample, and the associated factors. Results: The results showed that THB levels decreased from the first 16-weeks of pregnancy to the third trimester and increased from the third trimester to the 4-6 weeks postpartum for both groups. However, they differ in relation to the THB trajectories. For the adolescent cohort, the rebound in THB concentration between the third trimester and postpartum was not enough to make up for the initial losses, as happened to the adult cohort. For the adult group, higher THB levels were associated with planning of pregnancy and good self-rated health. Race was marginally associated to THB levels for both groups, with black/brown women presenting higher concentrations in the adolescent group and lower concentration in the adult group. Conclusion: Changes in THB concentrations during pregnancy and postpartum differ between adults and adolescents, with the latter presenting lower capacity to recover levels from the beginning of pregnancy through postpartum. Special attention to prenatal care among pregnant adolescents should consider their higher risk for adverse outcomes and include strategies that reduce the risk of anemia and its negative effects for the mother and her child.