Definition: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Input: Abstract: A prospective study of six unselected couples diagnosed as having unexplained infertility was done. In three of six patients, subtle abnormalities in follicular development were detected. In the first case poor follicular growth was observed. There was a premature small rise of luteinizing hormone (LH) with subsequent low levels of estradiol (E2) in the late follicular phase and unusual wide LH peak. This was followed by low progesterone levels in the luteal phase. In the second case follicular growth was abrupted by premature LH surge. This surge was triggered by early rise of E2 level while the follicle was still small in size. In the third case luteinized unruptured follicle syndrome was diagnosed, on ultrasound examination. All of the abnormalities were repetitive.

Human