the days of the menstrual cycle during which a woman is least likely to become pregnant; also in extended use.

The stage of the menstrual cycle which follows menstruation.

The stage of the menstrual cycle which precedes menstruation; the late luteal phase of the menstrual cycle.

Physiology. The middle of the menstrual cycle.

the part of the menstrual cycle during which conception is most likely.

The part of the menstrual cycle consisting of the last four days before and the first four days of menstruation.

Physiology. The recurrence at (normally) regular intervals of the heartbeat, breathing, or other physiological process; periodicity; an instance of…