[Ferrous sulfate supplementation in pregnant women: a time series study in the far South of Brazil].

The objective of this study was to assess the effect of some maternal characteristics on the use of ferrous sulfate among postpartum women from five perinatal studies in the Municipality of Rio Grande, Rio Grande do Sul State, Brazil. From January 1 to December 31 in the years 2007, 2010, 2013, 2016, and 2019, previously trained interviewers applied a standardized interview within 48 hours after childbirth to all postpartum women, while still in hospital, residing in the municipality and who had given birth in the only two local hospitals. The questionnaire included demographic, socioeconomic, and healthcare data during pregnancy and childbirth. Chi-square test was used to compare proportions and Poisson regression with robust variance was used in the multivariate analysis. The measure of effect was prevalence ratio. Among the 12,645 participants (98.1% of the total), 74.5% (95%CI: 74.7-76.0) had taken ferrous sulfate during the pregnancy. Prevalence varied from 61.7% (95%CI: 59.7-63.6) in 2007 to 81.1% (95%CI: 79.5-82.7) in 2019 (p-value for trend < 0.001). After adjustment, iron supplementation was significantly higher among adolescent pregnant women and those with less schooling (0-8 year), in the lowest income quartile, and who had received adequate prenatal care and care in the public healthcare sector (p < 0.05). There was a major improvement in the prevalence of ferrous sulfate supplementation during the period analyzed, but without achieving equity. To address this issue, healthcare professionals should prioritize older pregnant women, those with higher socioeconomic status, and those using the private healthcare sector for prenatal care.