<prompt> Which of the following method is the best predictor for ovulation in a female infeility patient during a menstual cycle?Basal body temperatureFern TestEndometrial biopsyHormonal Study  <response>: In an ovulatory cycle plasma progesterone reaches a peak of 15ngml at mid-luteal phase 22-23days. Basal body temparature BBT falls at the time of ovulation by about 12degree. During the progestational half of cycle temparature is slightly raised above the preovulatory level. But it is now obsolete because: 1. Tedious daily recording 2. Not very accurate 3. Better modalities are available In endometrial biopsy endometrium from the uterus is curetted preferably 1 or 2 days prior to the onset of menstruation. Histological examination done for secreatory changes. Now a days endometrial biopsy is omitted as a routine investigation of infeility. Only used in suspected tubercular endometritis Fern test: cervical mucus is examined under a low power microscope. During estrogenic phase it shows a characteristic fern patten which disappears after ovulation Reference: chapter 19; Infeilty and sterility; shaws textbook of gynecology - 16th edition 