Intermamillary indices in premature infants.

The internipple distance and its relationship to gestational age has not been studied in infants born in the United States. One hundred and thirty-three newborns between 25 and 40 weeks gestation showed progressive increase in the internipple distance with increasing gestational age. The internipple index stays constant during various gestational ages. The internipple index greater than 28% (greater than 2 SD) at any gestational age or during immediate postnatal age should be flagged to look into widely spaced nipples. Extrauterine growth of internipple distance is similar to that of intrauterine growth.