I took a pregnancy test and it was negative, but with my first child every test was negative till i was 18 weeks. ?

Not likely. : Urine pregnancy test for quite sensitive, despite which brand is bought. Most errors in reading them are due to either reading it too soon for waiting too long before it is looked at. It is highly unusual for a test to be negative repeatedly if one is truly pregnant. The most definitive way to confirm a pregnancy or lack of one is a blood test.