http://www.mayoclinic.com/health/air-travel-with-infant/HQ00197/METHOD=print
Mayo Foundation for Medical Education and Research
Air travel with an infant typically is safe. However, there are medical and safety issues to consider. A doctor may advise against unnecessary air travel during the first two weeks of life, when a newborn's body is still adjusting to life outside the uterus — and is especially vulnerable to the germs that circulate in the aircraft's recycled air.