Intrauterine means "inside the uterus."
A baby grows inside the mother's womb, or uterus (in an intrauterine environment).
An intrauterine device (IUD) is an object placed in the uterus to prevent conception and pregnancy.
Katz VL. Reproductive anatomy: Gross and microscopic, clinical correlations. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 3.