During the last half-century there has been a noticeable increase in a particular kind of first names for girls, specifically non-traditional forenames that derive from largely Anglo-Saxon surnames and end orthographically in –(e)y or –i(e) (pronounced identically, i. e., [-iy]). Whereas in earlier times this (quasi-)suffix––which also occurs in boys’ nicknames that are abbreviations (Bobby < Robert, Mickey < Michael, etc.)––modified (mainly WASP) girls’ nicknames like Missy, Sissy, or Trixie, it is now the unifying mark of popular Christian names like Tiffany, Kimberly, Hailey, Ashley, Avery, Kaylee, Riley, Bailey, Aubrey, Kiley, Sidney, Mackenzie, and even Serenity, Trinity, and Destiny, not to speak of older staples like Emily, Lily, Lucy, Molly, Naomi, etc. (NB: all these names––except for Missy, Sissy, and Trixie–– are drawn from the list of 100 most popular girls’ names compiled by the Social Security Administration for May 2011.)
Forenames like Ashley and Kimberly have the advantage of sounding like surnames while maintaining a tie with hypocoristic (here: affective) vocabulary, which means that they can do double duty for children and for adults, and not be mistaken for nicknames despite their phonetic resemblance to the latter.
It is clear that the attractiveness of names ending in [-iy] stems to a considerable extent from the (subconscious?) desire of parents to infantilize their female offspring in perpetuity, a motive that does not apply to males for obvious reasons. This onomastic trend is evidently of a piece with another linguistic feature, viz. the infantilization of female vocal timbre (“little girl voice”) beyond childhood into adolescence and adulthood, a trend that has been increasing in North American English for several decades, and that can only have the lamentable effect of subtly undermining some of the social gains of the feminist revolution.