To the Editor: I read the article by Prendergast et al with great interest (1). The results of this study are in contrast to our traditional belief. In this regard, I would like to point out few issues that needs urgent explanation before the study results can be accepted. First, the part of the hypothesis stating poor lung function in preterm infants exposed to chorioamnionitis is not fully correct as in various animal models antenatal inflammation has been found to increase the surfactant production and enhances lung maturation (2). Moreover in many human studies chorioamnionitis is associated with decreased incidence of RDS (3). Second, the distribution of the number of patients requiring any resuscitation after birth in each group is missing. Any positive pressure ventilation given during resuscitation will have influence on the lung functions. Third, the distribution of the infants in each group from the previous two studies is important to know because the various practices of resuscitation like use of air and oxygen mixture instead of 100% oxygen, use of PEEP, prolonged initial inflation time and introduction of early CPAP have changed over last few years, though the authors claim that there is no change in routine policies like antenatal steroid, surfactant etc. All this will affect the lung function and possibly BPD also (4, 5). Fourth, the first lung function measurement should have been done at the earliest after the initial stabilization rather than on D2 of life. The various interventions like amount of fluid received, presence of PDA, initiation of ventilation (invasive/non-invasive), will alter the lung function and the true influence of chorioamnionitis will get nullified. Fifth, more infants in the chorioamnionitis group were exposed to antenatal steroids (p=0.04) which could have partly influenced the lung function. Sixth, the surfactant has been given to symptomatic infants (rescue therapy). It is not the prophylactic use of surfactant as has been highlighted. Despite these limitations, I would like to appreciate the authors for their work, which has opened up the Pandora's Box.

References

1.Prendergast M, May C, Broughton S, Pollina E, Milner AD, Rafferty GF et al. Chorioamnionitis, lung function and bronchopulmonary dysplasia in prematurely born infants. Arch Dis Child Fetal Neonatal Ed 2011;96:270-74.

2.Kramer BW, Kallapur S, Newnham J, Jobe AH. Prenatal inflamemation and lung development. Semin Fetal Neonatal Med 2009;14:2-7.

3.Andrews WW, Goldenberg RL, Faye Petersen O, Cliver S, Goepfert AR, Hauth JC. The Alabama Preterm Birth Study: polymorphonuclear and mononuclear cell placental infiltrations, other markers of inflammation, and outcomes in 23 to 32 week preterm newborn infants. Am J Obstet Gynecol 2006;195:803 -8.

4.Siew ML, Te Pas AB, Wallace MJ, Kitchen MJ, Lewis RA, Fouras A et al. Positive end expiratory pressure enhances development of a functional residual capacity in preterm rabbits ventilated from birth. J Appl Physiol. 2009;106:1487-93.

5.Te Pas AB, Siew M, Wallace MJ, Kitchen MJ, Fouras A, Lewis RA et al. Establishing functional residual capacity at birth: the effect of sustained inflation and positive end-expiratory pressure in a preterm rabbit model. Pediatr Res. 2009;65:537-41.

Conflict of Interest:

None declared

Dear Sir,

The article by Prendergast et al describes an important outcome following a very common antenatal complication. However, there is no description of the proportion of infants surviving in the two groups which may overshadow any lack of difference in BPD development between the two groups. In the statistical methods no assessment appears to have been made in the regression model between duration of membrane rupture and BPD risk. An interaction could also have also been tested within the regression model to assess whether any effect modification exists between duration of membrane rupture and presence of chorioamnionitis. This additional information would be of use for counselling parents following delivery in the presence of chorioamnionitis.

Yours Sincerely Dr Neil Everest

Conflict of Interest:

None declared