If an ovum is fertilized during the luteal phase, which hormone is secreted?

When an ovum is fertilized during the luteal phase of the menstrual cycle, the hormone that is secreted is human chorionic gonadotropin (HCG). This hormone plays a crucial role in maintaining the corpus luteum after fertilization. The corpus luteum produces progesterone, which is essential for sustaining the early stages of pregnancy by maintaining the uterine lining and preventing menstruation.

In a normal cycle, once the ovum is fertilized, the developing embryo produces HCG soon after implantation. This action signals the corpus luteum to continue its production of progesterone and estrogen, supporting the pregnancy until the placenta takes over hormone production.

The other hormone options, such as FSH and LH, are involved in regulating the ovarian cycle and facilitating ovulation, but their roles decline after the luteal phase begins. Estrogen is also produced but primarily in conjunction with progesterone from the corpus luteum, instead of being the key hormone involved in signaling the continuation of pregnancy after fertilization.