**8. Leptin and recurrent pregnancy loss (RPL)**

Recurrent pregnancy loss may be defined as three or more consecutive spontaneous pregnancy losses occurring before the 20th week of gestation irrespective of previous live births [17]. Known causes include anatomical abnormalities, genetic causes, endocrine derangements, environmental factors, and immunological diseases. However, despite a thorough evaluation of the patients, the cause remains unknown in upto 50% of patients. Defects in the leptin signalling pathway have been evaluated as one of the possible causes of idiopathic RPL. Studies have demonstrated raised serum leptin concentrations in women with RPL as compared to controls. In contrast, reduced leptin levels were also observed in women having first trimester abortions. A recent study revealed similar leptin concentration in RPL cases and controls [50–53].

In conclusion, data linking recurrent pregnancy loss with leptin is largely inconclusive, though there is significant evidence suggesting positive association of hyperleptinemia with RPL.
