"our baby will first expire of inanition, as being the frailest member of our circle;..."
An uncommon term for failure to grow, either from insuffient food intake, or from inabililty to metabolize it.

Webster's 1913 Dictionary

Definition: \In`a*ni"tion\, n. [F. inanition, L. inanitio
emptiness, fr. inanire to empty, fr. inanis empty. Cf.
{Inane}.]
The condition of being inane; emptiness; want of fullness, as
in the vessels of the body; hence, specifically, exhaustion
from want of food, either from partial or complete
starvation, or from a disorder of the digestive apparatus,
producing the same result.

Feeble from inanition, inert from weariness. --Landor.

Repletion and inanition may both do harm in two
contrary extremes. --Burton.