Fig. 1

Categorization by milk type, feeding method, and subgroup classification. (A) Breastmilk-only: Exclusive feeding with breastmilk. A.1 Direct breastfeeding only: Feeding exclusively through direct breastfeeding. A.2 Bottle feeding with breastmilk only: Feeding exclusively with breastmilk via a bottle. A.3 Combined feeding method with breastmilk only: A combination of direct breastfeeding and bottle feeding with breastmilk. (B) Partial breastfeeding: Feeding that includes both breastmilk and formula. (C) Formula-only: Exclusive feeding with formula. (D) Direct breastfeeding only: Feeding the infant exclusively through direct breastfeeding. (E) Combined feeding method: Feeding through both direct breastfeeding and bottle feeding. (F) Bottle feeding only: Feeding exclusively via a bottle. F.1 Breastmilk only via bottle feeding: Feeding only breastmilk via a bottle. F.2 Formula only via bottle feeding: Feeding only formula via a bottle. F.3 Formula and breastmilk via bottle feeding: Feeding both formula and breastmilk via a bottle