The role of magnesium and thyroid function in early pregnancy after in-vitro fertilization (IVF): New aspects in endocrine physiology

BACKGROUND: The initiation of a pregnancy is a process that requires adequate energetic support. Recent observations at our Institution suggest a central role of magnesium in this situation. The aim of this study was to evaluate magnesium, zinc, selenium and thyroid function as well as anti-Müllerian hormone in early pregnancy following in-vitro fertilization as compared to spontaneous successful pregnancies. RESULTS: A successful outcome of pregnancy after IVF treatment was associated with 2 parameters: higher levels of anti-Müllerian hormone as well as higher levels of magnesium in the pre-stimulation blood sample. These two parameters, however, showed no correlation. Spontaneous pregnancies as well as pregnancies after IVF show a fall of magnesium levels at 2–3 weeks of gestation. This drop of magnesium concentration is larger following IVF as compared to spontaneous pregnancies. Parallel to these changes TSH levels showed an increase in early IVF-pregnancy. At this time point we also observed a positive correlation between fT4 and TSH. This was not observed in spontaneous pregnancies. Thyroid antibodies showed no correlation to outcomes. CONCLUSIONS: In connection with the initiation of pregnancy following ovarian stimulation dynamic changes of magnesium and TSH levels can be observed. A positive correlation was found between fT4 and TSH in IVF pregnancies. In spontaneous pregnancies smaller increases of TSH levels are related to higher magnesium levels. GENERAL SIGNIFICANCE: We propose that magnesium plays a role in early pregnancy as well as in pregnancy success independently from anti-Müllerian hormone. Neither thyroid hormones nor thyroid antibodies were related to outcome.