Associations between taking oral contraceptives and haematological parameters in adolescents

In this post-hoc analysis, the influence of oral contraceptives on haematological parameters in n = 2775 female German adolescents aged between 13 and 17 years was examined. Data from the nationwide representative Child and Youth Health Survey (KiGGS) of the Robert Koch institute in the years 2003 to 2006 were used. The cross-sectional KiGGS study used standardized and well-validated procedures and provided a large, unbiased data including self- and parents-rated assessment questionnaires. In addition, values of clinical laboratory parameters were recorded, which were collected from blood samples. In the descriptive analysis, it was found that girls aged 13 to 17 increasingly used contraceptives with age, up to 45% in the last birth year. In addition, girls without a migrant background showed a higher frequency of contraceptive use compared to migrants (22.0% versus 7.5%, p <0.001). Regardless of oral contraceptive use, there was a positive correlation between serum 25(OH) vitamin D and MCV (r = 0.136, p <0.001) and MCH (r = 0.047, p = 0.043), respectively. In contrast, serum 25(OH) vitamin D correlated negatively with the following parameters: RBC (r = -0.072, p = 0.002), MCHC (r = -0.111, p <0.001), sTfR (r = -0.123, p