Can you get pregnant if you are sick?

Every month when it is time to ovulate my child makes me sick, he is taking home al viruses from daycare. We have been trying for #2 for almost a year. I am afraid my immune system is attacking the new embryo since it is already busy fitting these viruses. Please tell me I am crazy and I still can get pregnant despite being sick. I have heard that the first two years of daycare is a non stop of sicknesses, and I really want baby #2 to come. Thank you in advance.