Preparation
Progesterone is the hormone of the second half of the menstrual cycle — released after ovulation, it prepares the uterine lining for pregnancy and sustains an early pregnancy. Measuring it in blood answers one precise question: did ovulation happen this cycle?
That makes the test a staple in fertility workups and treatments — confirming ovulation naturally, verifying that follicle-stimulating medication worked, and supporting early pregnancy assessment where miscarriage risk is a concern. Timing is decisive: the meaningful sample is drawn about 7 days after expected ovulation (roughly cycle day 21 in a 28-day cycle), on the day your gynaecologist specifies.
The draw itself is a few minutes at your home; the report reaches your app for your gynaecologist or fertility specialist to read against your cycle day. Book the exact day advised — a progesterone value without its cycle-day context tells no story.
About 7 days after ovulation — day 21 of a 28-day cycle. If your cycles differ, your gynaecologist will specify the day; the number is meaningless without that context.