['The objective of this study was to determine whether infants of mothers experiencing persistent nipple pain exerted very strong intraoral vacuums during a breastfeed.', 'Thirty mothers experiencing persistent pain during breastfeeding (Pain group; infants aged 49.4 +/- 35.5 days) were compared to 30 successfully breastfeeding mothers (Control group; infants aged 55.0 +/- 22.7 days). Infant intraoral vacuums were measured via a small milk-filled tube taped alongside the nipple and connected to a pressure transducer. Milk intake was measured using the test weigh method.', 'Infants in the Pain group applied significantly stronger baseline (-90.8 +/- 54.5 vs. -56.4 +/- 31.4 mmHg, p = 0.004), peak (-214.3 +/- 60.5 vs. 163.2 +/- 62.4 mmHg, p = 0.002) and pause vacuums (-104.8 +/- 67.9 vs. -45.8 +/- 30.3 mmHg, p < 0.001). Despite similar active sucking times (377.5 +/- 175.2 vs. 349.4 +/- 184.0 sec, p = 0.554) the mean milk intake was significantly lower for infants of mothers with nipple pain (41.6 +/- 31.3 vs. 70.7 +/- 30.7 g, p = 0.001).'] Do infants of mothers with persistent nipple pain exert strong sucking vacuums?