Even after adjusting for health-care worker type and experience, using WHO rather than NCHS charts increased: (i) concern: aOR 4.4 (95% CI 2.4–8.1); (ii) odds of referral: aOR 5.1 (95% CI 2.4–10.8); and (iii) odds of feeding advice which would interrupt exclusive breastfeeding (aOR 2.4, 95% CI 1.2–4.9). A preceding steady growth trend line did not affect concern, referral or feeding advice.