In general systolic BP in young females is less than that in the males of same age due to
Dietary habits
Oestrogen which prevents atherosclerosis
Progesterone effect on blood vessels
Low sympathetic activity
In females before menopause SBP is 4-5 mmhg less than that in the males of same age .After menopause SBP is 4-5 mmhg more than males of same age. This effect may be due to oestrogen which prevents atherosclerosis. Ref: page number 349 Textbook of physiology Volume 1 AK Jain 7th edition
Cardiovascular system