I have allergies, and when they're uncontrolled they tend to trigger my asthma. Some women can manage their allergies with nasal sprays and sinus rinses, but for me that doesn't help and the potential danger is too much of a risk. Albuterol is a class C drug because animal studies have shown it to be teratogenic (dangerous to the baby), so I really don't want to use my inhaler if it's not necessary. My MW made it clear to me that an asthma attack is more dangerous than albuterol, so in my book antihistamines are really the least evil. I am not apologetic about taking antihistamines when I need them.
Most antihistamines are class B drugs. That means that there have been no studies of it in pregnant women (well duh - who would participate?), but animal studies have shown them to be safe during pregnancy. The first line of treatment would be Benadryl or Chlor-Trimaton, which have been around for long enough that there is adequate human data to suggest they are safe. From my reading, Chlor-Trimaton is the drug of choice... but it puts me to sleep for like 13 hours, so it's not really an option. I use a mixture of Claritin, Zyrtec, and Benadryl. I tend to rotate them to spread the risk, and take the lowest dose that still has an effect on me (usually a half dose). And I only take it when I need it, rather than taking it every day to prevent allergies.
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