NOT a definitive sign of pregnancy:
Amenorrhea can be due to many reasons including pregnancy but also PCOS, Tuberculosis, Hypothalamic causes like Kallman's & Sheehan's syndrome , Pseudocyesis etc Remaining 3 are the definite signs of Pregnancy
Fetal skeleton on X-ray
Fetal hea sounds
Ultrasound examination
Amenorrhea
Diagnosis of Pregnancy