• 胎児たいじ — fetus; unborn baby
• 胎盤たいばん — placenta
• 胎内たいない — inside the womb
• 胎生たいせい — bearing live young (viviparity)
• 胎教たいきょう — prenatal education; stimulation before birth

On the left, にくづき shows flesh or the body, telling us this kanji is about something happening inside a living body. The right side adds the sound タイ and suggests a base that holds or supports something. Together, 胎 pictures a body that holds and protects new life — the womb and the growing embryo.