Unfortunately, I haven't been able to view an abstract or full text of the latest study by Borgwardt et al on respiratory illness in babies born by cesarean, but given the Danish study's title, 'Elective caesarean section increases the risk of respiratory morbidity of the newborn', the conclusion drawn is perhaps evident.
It will be interesting to find out what the gestational age of the babies involved in the above study were, but just in case there is any similarity with that of the well-publicized Anne Kirkeby Hansen et al study, I would like to re-emphasize what I said then.
Planned cesarean delivery with no medical indication is only advisable at 39 weeks confirmed gestation
This is in order to ensure that the baby's lungs are fully matured, since numerous studies have found that the lowest prevalence of respiratory morbidity occurs at 39 weeks gestation or more (some studies actually state that 38 weeks is acceptable, but the NIH and ACOG advise 39).
With the 2007 publication of Anne Kirkeby Hansen et al's study in the British Medical Journal, a number of responses followed, of which mine was one: 'Further evidence of reduced infant morbidity with cesarean delivery on maternal request at 39 weeks EGA.' This response explains in more detail why early gestational age, rather than surgery itself, increases the risk of respiratory illness in newborn infants.