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What’s Going on During My Menstrual Cycle?
Understanding your menstrual cycle can be key to achieving a pregnancy—after all, planning sex around ovulation can determine whether or not fertilization will occur. But what’s actually going on during each phase of your cycle?
Days 1 to 5: Your Period
Day 1 of your menstrual cycle is the first day of full red blood flow. During menstruation, or your period, your estrogen and progesterone hormone levels drop if the egg released in your previous cycle was not fertilized. This causes the lining of your uterus to shed. Your uterine lining sheds through the vagina, and what you see each month is actually a mixture of blood, mucus, and tissue. This bleeding usually lasts between two and five days.
Days 1 to 13: The Follicular Phase
At the beginning of your period, your body produces follicle stimulating hormone (FSH) and luteinizing hormone (LH). Around Day 5, your LH level increases, and your body produces estrogen which helps your follicles continue to mature. By Day 8 or so, one of the follicles becomes dominant and prepares for ovulation. Around Day 12, the increasing levels of estrogen will help your uterine lining thicken, as it prepares to host a fertilized egg.
Days 10 to 18: The Ovulatory Phase
This phase occurs in the middle of your menstrual cycle, and is marked by the occurrence of ovulation. The increase of LH causes the follicle to release an egg, usually around Day 14 of a 28-day cycle. The egg travels from the ovary to the fallopian tube, where it waits to be fertilized by sperm. The best chances for getting pregnant occur if you have sex slightly before or during ovulation. You are actually fertile for about 5 to 7 days before, during, and just after ovulation.
Days 15 to 28: The Luteal Phase
The corpus luteum, or follicle that released the egg during ovulation, now produces a hormone that causes your uterine lining to thicken for possible implantation. If the egg is fertilized, it will travel to the uterus to implant, usually around Day 20 of your cycle. If the egg is not fertilized, your FSH and LH levels will drop and a subsequent menstrual cycle will begin.