Evaluation of Repeated Antenatal Blood Testing for Anemia, Human Immunodeficiency Virus, and Syphilitic Infection Screening during the Third Trimester: A single-center university hospital setting

Abstract

Objectives: To compare first and repeated antenatal blood tests for screening anemia, human immunodeficiency virus (HIV), and syphilis serology status. Factors influencing maternal anemia were also evaluated utilizing multivariate analysis. Materials and Methods: A prospective descriptive study involved 1,089 pregnant women who attended an antenatal care unit in a university hospital setting. Participants were asked to fill in a questionnaire. Blood tests at the first antenatal visit and again during the third trimester, approximately 12 weeks apart, were performed routinely (in all women). An analysis was performed to compare the results from both blood sampling periods. Results: Hemoglobin and hematocrit levels were found to be significantly lower in the third trimester (first vs. third trimester; hemoglobin 12.2 ± 1.2 vs. 11.9 ± 1.2 g/dL, hematocrit 36.6 ± 3.5% vs. 36.1 ± 3.3%, p < 0.001). The incidence of anemia was 14.9% and 23.9% in the first and second laboratory tests, respectively (p < 0.001). Anemia diagnosed in the first trimester (odds ratio (OR) 5.46, 95% confidence interval (CI) 3.74-7.57), maternal underweight (OR 1.59, 95%CI 1.02-2.49), and poor compliance (OR 2.56, 95%CI 1.25-5.21) with ferrous supplementation were considered significant risk factors for anemic status being observed in the third trimester. The prevalence of HIV and syphilis infection were 3.6/1,000 and 1.8/1,000, respectively. Four syphilis seroconversions were observed in which 2 of these 4 were subsequently confirmed as syphilis infection by specific Treponemal test (0.2%). There was no HIV seroconversion in the study population. Conclusion: A significant decrease in hemoglobin and hematocrit levels warrants the need for a repeated complete blood count in the late trimester. Patients with risk factors, including i) first trimester diagnosis with anemia, ii) low body weight, and iii) poor compliance with taking antenatal supplements, require close monitoring to alleviate the severity of anemia at delivery. Due to a 0.2% seroconversion rate of syphilitic infection, the authors recommend repeat syphilitic serologic testing regardless of the sexual transmitted infection risks. Despite a high prevalence of HIV infection, absent of seroconversion in the study population warrants re-consideration of universal repeated screening of HIV infection in the third trimester. Further cost-utilization studies are required to draw conclusion regarding repeated serologic screening blood tests. © 2022 Thai Journal of Obstetrics and Gynaecology. All rights reserved.