Euphemistic, often used in informal or intimate contexts; the honorific prefix お softens the directness.
She shyly covered her vulva.
Kana spelling is the usual written form for this euphemism.
Katakana spelling sometimes used for emphasis or in informal contexts.
Honorific prefix お + 股 (また, 'crotch'). The exact origin as a euphemism for female genitals is uncertain, but it likely arose from indirect reference to the crotch area.