"Great post on this topic. While it's possible that incontrovertible evidence of a causal link between asthma and c-sections may be found one day, we are not there yet. Also, many of the studies published to date contain mixed cesarean data, yet we need to separate the associated risk of babies born via emergency cs, elective cs at various gestational ages, and elective cs for various medical and/or obstetrical indications.
I'd also agree with some of the posters here that even if a causal link IS proven, the risk of asthma for their child will still be assessed alongside other serious intrapartum risks with a trial of labor. The asthma debate is very similar to the one about whether c-sections increase your child's risk of obesity."