expression, godan verb (-su)
to be pregnant; to be with child
A somewhat literary or euphemistic expression for pregnancy, literally 'to harbor a child'. More common in writing than in casual speech.
彼女は子を宿していることがわかった。
She found out that she was with child.
The standard, clinical term for 'to become pregnant' or 'to be pregnant'. 子を宿す is more poetic and less direct.
Composed of 子 (child) + を (object marker) + 宿す (to harbor, to lodge). The phrase literally means 'to harbor a child'.