Translation guide
A baby in the first few weeks of life. Japanese has several common terms, with 赤ちゃん being the most general and warm, while 新生児 is the formal medical term.
The most common, affectionate way to refer to a newborn or infant in everyday conversation.
The standard, warm, and widely used word for a baby, especially a newborn. Safe for most situations.
赤ちゃんが生まれたよ。
We had a baby! (lit. A baby was born.)
その赤ちゃんはとても小さい。
That newborn baby is very small.
Also means baby/infant, slightly more matter-of-fact than 赤ちゃん. Commonly used for newborns as well.
赤ん坊が泣いている。
The newborn baby is crying.
Used in medical contexts, official documents, or when precision is needed.
The formal term for a newborn, typically up to 28 days old. Used in hospitals and official records.
新生児の体重は3キロでした。
The newborn baby's weight was 3 kilograms.
新生児集中治療室
neonatal intensive care unit (NICU)
Emphasizing the very early period after birth, often in parenting or childcare contexts.
Literally 'a baby just born'. A natural phrase to emphasize the newness.
生まれたばかりの赤ちゃんはよく寝ます。
Newborn babies sleep a lot.
Means 'a baby soon after birth'. Slightly more formal than 生まれたばかり.
生後間もない赤ちゃんの世話は大変です。
Taking care of a newborn baby is tough.
赤ちゃん is the everyday word for any baby or infant, including newborns. 新生児 is strictly a medical/formal term for a baby in the first 28 days. Use 赤ちゃん in casual conversation, 新生児 at the doctor or on forms.