Breastfeeding rates in the Republic are improving faster than they are in the North.
58 percent of new mothers in the Republic breastfeed their babies, compared to 45 percent north of the border.
The widening gap is highlighted in an all island report from the Institute of Public Health.
The main reasons for not breastfeeding include a preference for formula feeding, inconvenience and fatigue.
Women also pointed to embarrassment and public attitudes.