Menstrual Cycles and your Fertile Days

Menstrual Cycles

The average menstrual cycle is 28 to 32 days. Some women have longer or shorter cycles, so the exact timing of ovulation can vary. Here's an overview of a typical 28-day menstrual cycle.

Day 1

Your cycle begins on the first day of blood flow.

Days 2-14 Follicular Phase

The follicles on your ovary become active, and your cervical mucus starts to thin.

Day 14

Ovulation occurs mid-cycle, but can vary from between Day 11 and Day 21 of a woman's cycle. Rising estrogen levels trigger the LH surge, which causes the follicle to ovulate and release an egg. It's important to chart your basal body temperature and LH surge so you know when you ovulate.

Days 15-22 Luteal Phase

After releasing the egg, the follicle produces progesterone, which thickens the lining of the uterus for implantation.

Days 23 to 24

Implantation of a fertilized egg can take place. At this point, hormones produced by pregnancy may be detected by a pregnancy test.

Days 25 to 28

If pregnancy does not occur, your hormone levels begin to fall. The uterine lining sheds, resulting in your period.