A tumor is an abnormal mass of tissue, which doesn't necessarily mean that you have cancer. Tumors can be benign, not cancerous, or they can be malignant, pre-cancerous. Another name for a tumor is a neoplasm.
Swelling is a sign because when you swell up then you know theres something wrong
The main factors affecting birth are:
Age.
Health.
Heredity.
Ovulation cycle.
Location.
Miscarriage