Introduction: We are not aware of a published reference range for heart rate in VLBW infants and such knowledge might be useful in the acute postnatal transition.

Objective: To determine the limits of HR in VLBW infants <32 weeks gestation on each of the first 7 days of life.

Study Setting: SE Scotland tertiary referral NNICU (12 computerised IC cots since 1991).

Patients: a database of physiological information on 304 VLBW infants, all of whom required IC.

Measurements: HR data accumulated at 1 sec intervals from HP 78834A multichannel monitors to a computerised monitoring system were saved as 1 min averages.. HR artifact was excluded, but no attempt was made to divide babies into groups with and without blood pressure support or that survived or died.

Results: Expressed as mean and 95%Confidence Interval for each day. The number of infants at each gestation is <25w, n=23; 25w=19; 26w=27; 27w=33; 28w=40; 29w=53; 30w=43; 31w=30. Table

Table 1
Full size table

Conclusion: A reference range of HR is given over the first week of life. At each gestation the HR rises for 2-3 days after birth before stabilising. On days 2-5 there is a steady decrease in heart rate with increasing gestation which is present but not so obvious on day 1, 6 or 7.