Table 2.

Inclusion and exclusion criteria for selecting articles (PICOS)

Parameter	Inclusion criteria	Exclusion criteria
Population	Chinese population; healthy mothers	Non‐Chinese populations; non‐human; mothers or infants with defined diseases or disorders (premature delivery was not regarded as diseases or disorders)
Intervention	N/A	N/A
Comparator	N/A	N/A
Outcomes	Human milk samples; data were expressed as means or medians; lactation stages could fit into the categories of 1–7, 8–14, 15–30, 31–60, 61–90, 91–365 postnatal days	Lactation stage not specified or simply described as colostrum, transition milk, or mature milk
Study design	Original articles from peer‐reviewed journals; master theses or doctoral dissertations that reported original research data	Review articles; abstracts; articles without access to full‐text; milk samples were pooled together before assessment