noun
lactation period; nursing period
Refers to the period during which a mother breastfeeds her infant, or more broadly the suckling stage in mammals.
哺乳期の赤ちゃんは、夜中に何度も起きることが多い。
Babies in the nursing period often wake up many times during the night.
哺乳期の栄養は、母親の食事に大きく左右される。
Nutrition during the lactation period is greatly influenced by the mother's diet.
離乳 means weaning, the process of transitioning an infant away from milk, marking the end of the 哺乳期.
Compound of 哺乳 (ほにゅう, 'suckling, nursing') and 期 (き, 'period'). The word is straightforward and modern.