also: はら
noun
Medical or literary term for the womb. In everyday speech, 子宮 (しきゅう) is more common.
胎内で赤ちゃんが育つ。
The baby grows inside the womb.
胎の健康状態を超音波で調べた。
They checked the health of the womb with an ultrasound.
子宮 is the standard everyday and medical term for uterus/womb. 胎 is more literary or used in compounds like 胎児 (fetus) and 胎盤 (placenta).
The kanji 胎 is composed of 月 (flesh/body part) and 台 (phonetic component suggesting 'to contain'). It has been used in Chinese and Japanese to refer to the womb or fetus.