Pregnancy can be detected by a blood test at about 14 days (from the date of ovulation), but the exact earliest time varies from person to person.
The blood test for pregnancy is mainly for human chorionic gonadotropin (HCG), a glycoprotein hormone secreted by placental trophoblast cells, which is the standard for determining whether or not you are pregnant.
HCG is secreted by placental trophoblast cells at the time of fertilization of the egg. Since the blood concentration of HCG is very low at the beginning and cannot be detected, pregnancy can be diagnosed if the blood HCG is significantly higher than the normal level when examined 14 days after ovulation. However, some women’s HCG levels will start to rise after 7 days of coitus, so the exact earliest time to detect pregnancy varies from person to person.
After blood sampling indicates that human chorionic gonadotropin is significantly elevated, the gestational sac can be seen in the uterine cavity by vaginal ultrasound or abdominal ultrasound around 35 days after menopause, and the fetal buds and primitive heart tube pulsation can be seen by ultrasound around 6 weeks of pregnancy.
Generally speaking, by checking human chorionic gonadotropin and vaginal ultrasound or abdominal ultrasound, it is possible to diagnose whether the pregnancy is intrauterine or not, and after the pregnancy is clearly defined, regular obstetric examination and follow-up should be done.