ADC -- eLetters for Iyer et al., 93 (4) 297-299

Iyer et al [1] report the effects of a neonatal weight monitoring policy on the incidence of hypernatraemic dehydration.� This policy led to an increased recognition of affected infants, but identified cases at an earlier and milder degree of dehydration. �We examined the effect of introducing a similar policy on cases of more severe dehydration.� We wished to test whether the background rate of hypernatraemic dehydration was rising and to test whether a weight monitoring policy had any effect on the background incidence.�

We studied cases of moderate/severe hypernatraemic dehydration in infants born in a single maternity unit attached to the sole inpatient paediatric unit for the city.� The maternity unit delivers approximately 3,500 births per annum.� Infants requiring readmission in the neonatal period may be admitted to the paediatric inpatient unit or to the maternity hospital of birth.� We reviewed the biochemical records for nine years (January 1998 - December 2006) from the single laboratory that serves both the paediatric inpatient unit and the attached maternity unit. We identified 198 cases of infants under the age of four weeks with a plasma sodium of >150mmols/l.� We were able to obtain and review 178 (90%) of these case-notes. Many cases of hypernatraemia were due to underlying medical or surgical problems including prematurity. We identified 67 cases of hypernatraemic dehydration in otherwise healthy breast-fed neonates during this period. A weight monitoring policy was introduced at the end of 2003. Babies were weighed around days 2, 5 and 10 and those with >10% weight loss were seen by specialist breast-feeding support sisters for supervised feeding, advice on positioning and milk expression. Initially, we compared the 3-year period from 1998 to 2000 with the 3-year period from 2001 to 2003, using as a denominator the number of breast-fed infants discharged from the maternity unit during that period. We compared the number of cases between 1998 and 2003 with those in the 3-year period that followed. The table documents the weight, age and plasma sodium at presentation. Data is presented as median and range in view of its skewed distribution.

Comparison of the two 3-year periods prior to policy implementation showed no significant change over this time (1998-2000: 4.54% and 2001-2003: 4.99%).� Comparison of the 6-year period prior to the introduction of our policy and the 3-year period following, documents a fall in incidence from 4.77 to 2.94 cases per 1000 breast fed infants p = 0.066, 95% CI = -3.77 to + 0.12. The pre and post policy incidence using the number of live births as the denominator is 2.4/1000 and 1.5/1000 respectively.

The incidence of hypernatraemic dehydration in our study is less than that reported by Iyer of 7.4 cases/1000 live births. This is not surprising as we report only the more severe cases. In Iyer�s study the policy of neonatal weight monitoring led to an increased identification of hypernatraemic infants but reduction in severity of the identified cases. Our study supports this; we only looked at more severe cases but observed reduced numbers of such cases to a degree that could potentially be very important clinically.

It is concerning that we continue to see reports of serious thrombotic complications of neonatal hypernatraemic dehydration [2,3]. These cases may be preventable if recognised earlier. Clinical assessment is important and all professionals dealing with breast-feeding mothers and their infants need to be trained to recognise the clinical cues of an infant who is not receiving an adequate intake. However weight monitoring can provide a valuable safety-net to identify such infants earlier, allow targeted additional breast-feeding support and prevent more severe cases. Data is available to allow thresholds to be set for intervention and support [4,5].

We have previously demonstrated that introducing such a weight monitoring policy does not adversely affect the number of mothers breast-feeding and suggested that identifying and addressing problems at an earlier stage would encourage mothers to continue breast-feeding who might otherwise have given up [6]. Iyer�s work supports this, demonstrating an increase in the rate of breast-feeding at final discharge amongst their cases of hypernatraemic dehydration.� We did not see this in our more severe cohort but it is likely that our post-policy group represents more refractory cases that have failed to respond to initial attention to feeding position and attachment.

We would encourage the widespread adoption of a policy of neonatal weight monitoring as it is likely to identify cases of hypernatraemic dehydration at an earlier stage when intervention can support continued breast-feeding and reduce the incidence of more severe cases.

	Pre-policy 1998-2003	Post-policy 2004-2006
Incidence/1000 breast-fed infants	4.77	2.94
No of cases	51	16
Percent of cases breast-fed at final discharge	59%	50%
Weight loss at presentation (%): median (range)	14.0 (6.4-23.7)	13.5 (10.2-21.5)
Age at presentation (days): median (range)	4 (2-11)	4 (3-8)
[Na⁺] at presentation (mmol/l): median (range)	153 (151-172)	154 (151-167)

Table

Effect Of Weight Monitoring Policy On Cases Of Hypernatraemic Dehydration

References

1. Iyer NP, Srinivasan R, Evans K et al. Impact of an early weighing policy on neonatal hypernatraemic dehydration and breast feeding. Arch Dis Child 2008; 93: 297-299.

2. Shroff R, Hignett R, Pierce C, et al. Life-threatening hypernatraemic dehydration in breastfed babies. Arch Dis Child 2006; 91: 1025-1026.

3. Fawke J, Whitehouse WP, Kudumula V. Monitoring of newborn weight, breast feeding and severe neurological sequelae secondary to dehydration. Arch Dis Child 2008; 93: 264-265.

4. Macdonald PD, Ross SRM, Grant L, et al. Neonatal weight loss in breast and formula-fed infants. Arch Dis Child Fetal Neonatal Ed 2003; 88: F472-476.

5. Van Dommelen P, van Wouwe JP, Breuning-Boers JM, et al. Reference chart for relative weight change to detect hypernatraemic dehydration. Arch Dis Child 2007; 92: 490-494.

6. McKie A, Young D, Macdonald PD. Does monitoring newborn weight discourage breastfeeding? Arch Dis Child 2006; 91: 44-46.