The state of being a woman who is not a mother; women who are not mothers collectively.
We have gone without definition or visibility for too long. I am
offering “Otherhood“ as a name for our misunderstood group of
women doing our best to live full and meaningful lives despite the
frustrations of some of our most cherished Iongings. We, the Otherhood, who have yet to find our rightful, equitable, requisite place in society, deserve one. Our otherhood denotes our state. our condition, our character, our nature, and our tribe.
—Melanie Notkin, Otherhood, Seal Press, February 25, 2014
Among the salient findings of the study, women of the “otherhood” are “thriving career-wise,” and 75% of them had some college education or above, compared to 67% of women with kids, according to a report on the research.
Motherhood versus otherhood is the battle at the centre of Georgia Fitch’s personality packed but lightweight investigation of the modern woman, I Like Mine with a Kiss....
Two best friends embody two sides of the issue. Annie is a single parent who defines herself by her motherhood. Aligned against her is Louise, a mess of feminist theory and self-hatred who spurns the idea of childbearing.
—Kieron Quirke, “Mother of all battles over motherhood,” The Evening Standard (London), February 19, 2007
There are a number of earlier citations that play on motherhood/otherhood, but use the latter to mean something closer to "being an outsider" rather than "being a non-mother." Probably the earliest of these is the following 1990 cite:
IV. “The Joys of ‘Otherhood’”: A Hearing of The Joys of Motherhood.
—Cynthia Ward, “What They Told Buchi Emecheta: Oral Subjectivity and the Joys of ‘Otherhood’,” PMLA, January 1, 1990