Effect of Progesterone-only Contraception on Vitamin D in Human Milk

Objective: Nowadays progesterone contraceptives are being used by lactating women. In the last century elements effective in bone growth in infants, such as calcium, phosphorus and vitamin D have been evaluated. Vitamin D has been mentioned mainly in relation to rickets prevention in infants. This study was initiated in order to investigate the effect of Progestin-only contraceptives on breast milk vitamin D.
Material & Methods: In this cohort study 138 lactating womenwere assigned to either the hormonal (52 participants) or non-hormonal (86 participants) groups according to their chosen method of contraception. The characteristics and goals of the study were explained in detail and informed consent was obtained from all subjects before inclusion in the study. Research units started their method of contraception 45 (7) days postpartum and continued at least for 6 months afterward. 10 ml milk samples were obtained before the baby nursed at 6 mos postpartum, and kept at -20 °C until analysis. Vitamin D levels were measured with RIA method.
Findings: Vitamin D levels were found to be 11.2 (7.2) nmol/L in the hormonal and 10.67±6.6 nmol/L in the non-hormonal groups, which was lower than other cultures. There was not a significant difference between the vitamin D levels of the two groups statistically (P>0.05).
Conclusion: According the results, the consumption of progesterone-only contraceptives had no effect on the vitamin D levels of mothers' milk, although with regard to low levels of vitamin D in the milk of lactating mothers, it is necessary to enrich foods with vitamin D and for mothers to use vitamin D supplements.