What is going on in this chart?
1) Low temperatures, and increasingly fertile cervical fluid in the follicular (preovulatory) phase.
2) Unprotected sex during first 5 days of cycle, and in the evening of days when no cervical fluid is present.
3) Protected sex during the fertile window. From the first sign of cervical fluid until 4 days after the Peak Day, and 3 days after the temperature shift, she is considered fertile.
4) This sustained temperature rise indicates that ovulation has occurred.
5) During the infertile part of the luteal phase, she is considered infertile, and is safe to have unprotected sex again.