Alterations in red blood cell parameters associated with the use of hormonal contraceptives

Abstract

Introduction. Hormonal contraceptives are widely used worldwide due to their effectiveness in preventing unwanted pregnancies. In addition to their contraceptive function, these drugs offer multiple non-contraceptive benefits, such as regulating the menstrual cycle, reducing pain associated with dysmenorrhea, decreasing excessive menstrual bleeding, and treating acne and polycystic ovary syndrome. However, numerous studies have shown that their use can induce changes in hematological parameters, particularly in the red cell series and platelets. These modifications vary depending on the type of contraceptive, the route of administration, and the duration of treatment. Objective. To analyze the alterations in red blood cell parameters and platelet count associated with the use of diverse types of hormonal contraceptives in women. Methodology. An information search was conducted in various databases, including PubMed, Scopus, BVS, Cochrane Library, Elsevier, and books, considering studies published in both English and Spanish. Results. Combined oral contraceptives and quarterly progestogen-only injections are associated with clear increases in red blood cell count, hemoglobin, hematocrit, and platelet count. In contrast, transdermal patches, the vaginal ring, and the hormonal IUD maintain stable erythrocyte indices and platelet counts. Subdermal implants, on the other hand, do not usually alter these parameters initially, but prolonged use can cause irregular uterine bleeding, which over time leads to a decrease in red blood cell count, hematocrit, MCV, and MCH due to the progressive depletion of iron stores. Conclusion. The hematological effects of hormonal contraceptives vary according to their type and duration of use. While combined oral contraceptives and injectable progestogens promote an increase in erythrocyte and platelet parameters due to reduced menstrual bleeding and possible erythropoietic stimulation, chronic use of subdermal implants may induce changes consistent with iron deficiency. General field of study: Health Sciences Specific field of study: Clinical Laboratory Type of study: Narrative literature review.