expression, godan verb (-ru)
hold one's head up (of an infant)
Used when a baby's neck becomes strong enough to support the head without help. A developmental milestone.
生後3ヶ月くらいで首がすわる赤ちゃんが多い。
Many babies can hold their heads up by around three months of age.
首がすわるまでは、抱っこするときに頭
Until the baby can hold its head up, please support its head when you hold it.