Which statement best describes colostrum and the onset of transitional milk?

• A. Colostrum is the initial thick yellowish milk rich in immunoglobulins; transitional milk begins about day 3-7 postpartum.
• B. Colostrum is thin watery milk; transitional milk begins immediately after birth.
• C. Colostrum is not produced until day 7; transitional milk begins day 10.
• D. Colostrum is high-fat milk; transitional milk begins day 1.

Answer: (A)

Understanding the lactation timeline helps explain why colostrum and transitional milk differ. Colostrum is the first milk produced after birth; it’s thick and yellowish and is rich in immunoglobulins (especially IgA) and protein, while the volume is limited. This early milk provides passive immune protection and supports the newborn’s gut. After a few days, the milk composition shifts to transitional milk, which typically begins around day 3 to day 7 postpartum. Transitional milk has more fat, lactose, and calories and a higher volume, signaling the move toward mature milk. Mature milk generally comes in by about two weeks postpartum.

So the best description is that colostrum is the initial thick yellowish milk rich in immunoglobulins, and transitional milk begins about day 3–7 after birth. The other statements mischaracterize the nature of colostrum or the timing of the transition.