The main issue with colds and flus is that women who do get sick during pregnancy tend to get “sicker” (or experience worse symptoms) than nonpregnant women, and if your symptoms get out of control, it can affect the fetus. Dehydration specifically can lead to preterm contractions, and a high fever (over 103 degrees Fahrenheit) early on in the pregnancy can lead to a birth defect. So if you do come down with something, it’s important to make sure that you keep your fever down, stay well-hydrated and get enough rest. And if you can't keep any fluids down because of nausea or vomiting, be sure to let your doctor know.
Expert : Ashley S. Roman, MD, MPH, clinical assistant professor in the department of obstetrics and gynecology at New York University-Langone Medical Center