What is the definition or description of: poor suck?

For many reasons: an infant may have difficulty feeding. One is inability to orchestrate latching on to the breast and generating the suction required to extract milk from the breast or bottle. This is called poor suck. It can be the result of illness, central nervous system insult, tongue tie or fatigue. Low blood sugar can also cause this.

Poor sucking: Have a breast feeding consultant review feeding. If your baby seems otherwise sick have him/her seen by your MD. It is often a mechanical issue involving the baby's mouth or the anatomy of the breast. There are devices that can help. All the best and I hope breast feeding works for you.