Iv just found out I'm pregnant after nearly two years ttc

Please read ! My partner had a low sperm count mobility and morphology and we've been ttc for nearly two years we've had one early miscarage and was just about to start ivf because they doctors says its nearly impossible to concieved with the number he has but left us for a couple of months jusy incase cus we had already concieved!!! Anyway I am like only 4 weeks pregnant and I'm petrified I am going to miscarry does anyone know if I am more like because my partners spearm analasis wasn't great ??? Any advise would jusy be brilliant !!!!! Thankyou