Hcg levels

Breean • Mama to Delilah Mae Dexter Kash and Declan Grey 💖
How long do hcg levels stay in your system after birth? My friend had a baby the day before me (I had my son May 4th) and had unprotected sex multiple times ... I've heard you could get a false positive if there are left over hcg hormones in your body still .