Possible to be pregnant after 7 negative hpts and 1 neg qual hcg blood test.. been 18 weeks since sexual contact?

Not in normal life: Pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, sexually transmitted diseases, vaginal spotting, or medications. A test gives a reliable result 3 weeks after sex (2-3 weeks after when conception might have happened) or 1 week after missing a period. If done sooner, a negative result may be due to testing too early such as less than 2 weeks after conception.