OOPS, forgot a few other things I like to look at, that might affect infant's suck:

1) how are the infants fetal heart tracings?     were there lots of of compromising situations like deep variables or; bradycardias, or were there those ominous late decels?

2)  what are mom's breasts and nipples like?  While we never 
say it to a mom, some breasts/nipples are easier for                        an infant to learn on than others.  Protruberent nipples                        are able to be put into infant's mouth, to some extent,                        and don't get dropped/pushed out while the baby is                        coordinating other facets of the suckling.