But within that group there is a great deal of gradation—much of it tied to specific timelines within pregnancy.
1530s, "climax," from Middle French gradation (16c.) and directly from Latin gradationem (nominative gradatio) "ascent by steps, a climax," noun of action from gradus "step, degree" (see grade). Meaning "gradual change" is from 1540s. Related: Gradational.