Hi, Yes, you can become pregnant despite using of IUD but it is very rare. IUDs are more than 99% effective. Less than 1% women can become pregnant with IUD. Hormonal IUD like mirena IUD carries the same failure rate as nonhormonal or Copper IUD. If your IUD has been kept for a long time and exceeded its expiry date, then you can become pregnant from a unprotected sexual intercourse. Without knowing your last day of the last menstrual cycle, starting time of your next usual menstrual cycle and history of amenorrhea, it is difficult to predict the chance of your pregnancy. Home pregnancy tests are accurate as long as you follow the instructions correctly. It can be almost 99% accurate. When you become pregnant, your body starts to produce increased amount of hormone known as human chorionic gonadotrophin (HCG) . Home pregnancy tests detect the surge of HCG in your urine. As your urine contains highest concentration of HCG in the morning after awaking from sleep, so do the test at this time. Avoid drinking too much fluid before test as this can dilute the level of HCG. Nausea is not a disease, it is a symptom of disease. Yes, nausea may result from stomach bug which is known as gastroenteritis. Besides pregnancy and gastroenteritis, the other reasons which can cause nausea including morning sickness, peptic ulcer disease, acid reflux, gallbladder stone, urinary tract Infection, gastroparesis, pain, viral Infection, migraine etc. Take care. Hope I have answered your questions. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General and Family Physician,