Drugs are categorized for pregnancy classes A through D and X, A being well studied and proven safe to D and X being studied and proven dangerous to a growing fetus. So for us pregnant moms with Cf, there is a risk/benefit ratio that needs to be discussed with each patient and each drug. It differs from person to person.
I'm on my 3rd pregnancy, and I remained on Zithromax, Pulmozyme, Albuterol, and Hypertonic Saline for all. I also am on Pulmicort for all pregnancies which is switched from my usual Advair. For my current pregnancy I have been also been able to use Cayston, which is a wonderful tool, especially since they did a study on it related to fetal safety since my last pregnancy and its very safe. My doctor does not recommend Tobi during pregnancy and I opted to stay off that, though I know others that have used it.
There are many situations that come up during pregnancy, and depending on what you culture, in all likely hood you will have several safe options to get you through. Its important to remember that a healthy mommy equals a healthy baby. Also, being at optimum health before you are pregnant is key, so a good tune up prior to getting pregnant may work well for some.
Yes I ditto infantrisk.com for breastfeeding/drug questions. They are wonderful. Important to remember that med safety is completely different in pregnancy vs. breastfeeding. So they will have the most up to date info on breastfeeding if you desire/are able to do that.
Best wishes!