If a woman has intercourse during ovulation and is pregnant, the number of days it takes to test for pregnancy depends mainly on the method used to test for pregnancy. If a blood test is done, it will only take 7-10 days after ovulation to detect the pregnancy, while if a urine HCG test is done with an early pregnancy test, it will take longer, about 15-20 days. If you use an ultrasound to determine if you are pregnant, it can take even longer, perhaps 3-4 weeks after ovulation, to confirm the diagnosis. A woman’s fertility rate is higher when she has intercourse during ovulation because there are mature follicles. The body secretes a hormone called chorionic gonadotropin, or HCG, which is found in the blood and urine of the body and increases as the fertilized egg develops. The level of HCG in the blood increases faster than in the urine, so a blood test for HCG levels in the blood can be done 7-10 days after fertilization to determine if you are pregnant. Because HCG levels in urine increase more slowly, it takes about a week beyond the menstrual cycle to test for it, about 15-20 days before ovulation. On the other hand, to confirm pregnancy through ultrasound, the main purpose is to see if there is a gestational sac in the uterine cavity under the ultrasound. The gestational sac needs to go through a series of pathways before it can enter the uterine cavity, so the time is relatively later, and it may take 3-4 weeks before ovulation.