Final answer:
The amount of estrogen is lower during menstruation compared to ovulation. Estrogen levels peak during ovulation, triggering the release of an egg, while they are lower at the start of the menstrual cycle when the uterine lining is shed.
Step-by-step explanation:
The amount of estrogen in the blood during menstruation is lower than the amount of estrogen in the blood at ovulation. During ovulation, there is a surge in estrogen levels, which triggers the release of an egg from the ovary.
Estrogen levels rise during the luteal phase of the ovarian cycle, which follows ovulation, and the secretory phase of the uterine cycle. In contrast, during menstruation, which marks the beginning of a new menstrual cycle, estrogen levels are relatively low as the body sheds the uterine lining. After ovulation, if fertilization does not occur, the corpus luteum degenerates, leading to a decrease in estrogen, and this initiates the next menstrual cycle.
It is important to understand that hormonal levels fluctuate throughout the menstrual cycle, influencing various reproductive processes. Estrogen levels are critical for regulating the cycle, affecting the ovaries, uterus, and overall fertility. Thus, the menstrual phase is characterized by lower estrogen, contrasted with the higher levels present during the ovulatory phase.