Breastfeeding

Breastfeeding (also called nursing or suckling) is a normal physical act between a mother and her child during the child's infancy, when a female's mammaries are used to feed milk to her child.

Empath: The Luckiest Smurf stories
Breastfeeding is done among the female Smurfs to their children in the EMPATH: The Luckiest Smurf story series, although it is usually done with discretion and privacy so as not to draw unwanted looks upon themselves by the male Smurfs. Smurfette, being mindful of this, usually covers herself and her child Psycheliana with a blanket whenever she breastfeeds in public.

Hero: The Guardian Smurf stories
There is at least one recorded case of one of Hero's wives breastfeeding their child in the HERO: The Guardian Smurf story series, though due to the rather sensitive nature of this routine, Hero advised her to cover herself so as not to draw any unwanted attention unto herself.