Girls, I'm back for advice. I'm pregnant 9 weeks. My son is almost 4 y…

Girls, I'm back for advice. I'm pregnant 9 weeks. My son is almost 4 years old, and since I found out about the pregnancy, I haven't taken him to daycare. I'm afraid he might bring some infection (measles, chickenpox, scarlet fever). I'm waiting until 12 weeks. Do you think it's worth returning him to daycare or should he stay home until the end of my pregnancy? He gets sick there often, mostly with phlegm. I myself didn't get these infections in childhood according to my mom. Has anyone ever had scarlet fever, chickenpox, measles during pregnancy?