Having recently reviewed the case notes of babies readmitted to hospital in the first 10 days of life (over a one year period), we firmly agree with the views expressed by Laing and Wong.¹ The incidence of documented hypernatraemic dehydration secondary to the failure of lactation in Bristol is 1.7 per 1000 live births much higher than that described by Oddie et al in the Northern Region (2.5 per 10 000 live births).² In addition only 50% of infants readmitted with weight loss of <10% had a plasma sodium concentration measured. The true incidence of hypernatraemic dehydration secondary to lactation problems in …