Answer:
From the date of last menstruation, pregnancy is considered.
Step-by-step explanation:
The pregnancy lasts approximately 9 months (40 weeks from the first day of the date of last menstruation). The first thing that can be detected is the increase of the human chorionic gonadotrophin hormone in the blood during the first days of pregnancy, then the hormone is detected in the urine (with the famous evatest).