Hello, Thankyou for asking your question at healthcare magic. I understand your concern Taking thyronorm during pregnancy is completely safe.Infact it is important to take the thyronorm regularly, if you have hypothyroidism (decreased thyroid hormone ) and regularly check the thyroid hormone levels.Maintaining a normal thyroid level is important for mother and fetus. The earliest signs of pregnancy occur when the fertilized egg implants on the uterine wall.Some women notice slight bleeding /spotting at this time called Implantation bleed.But most women do not have Implantation bleed. Once the fertilized egg implants the progestrone lvels in your body keep.rising and you start noticing increase in body temperature, nausea, breast tenderness,bloating etc . However some women do not exprience any of these symptoms, even though they have conceived. Implantation usually occurs around 9 th day after ovulation.It can range from 6-12 days.Assuming you have regular periods ,your ovulation is supposed to happen on day 14.If so,you are unlikely to have any symptoms of pregnancy on day 20 of the cycle. You can do a home pregnancy test 6 days after your missed periods to detect pregnancy.Now there are also very sensitive tests available that test for pregnancy 5 days before missing your period, but chances of getting false negative results are high if you test too early Hope I was able to answer your question Please feel free to address any more concerns Regards, Dr.Lekshmi