In my research, I found that the levels of "gonadotropins" in the body are critical to understanding how the drugs Clomid and Ortho Tri-Cyclen work. What are gonadotropins? What role do they play in fertility?

Gonadotropins are hormones secreted by the pituitary gland and the placenta.

Explanation:

Gonadotropins are heterodimeric glycoprotein hormones secreted by the endocrine system in vertebrates. Gonadotropins include pituitary hormones such as follicle-stimulating (FSH) and luteinizing (LH) hormones, and placental gonadotropins such as chorionic gonadotropin (CG) chorionic gonadotropin (CG) hormones which are secreted during pregnancy. Gonadotropins play critical roles in growth, ovarian germline cell mitosis/meiosis decision and sex hormone production. In humans, menopausal gonadotropin hormones are secreted by the pituitary gland in order to stimulate ovulation.