Requirements for a Pregnancy Test to turn positive
When the fertilized egg gets implanted into the uterus and starts sending hCG hormone into your blood stream in sufficient quantities, your pregnancy test will become positive. About 6 to 12 days after ovulation, the fertilized egg implants into the endometrium. This is known as implantation. The blood pregnancy test becomes positive 3 to 4 days after implantation.
- Blood pregnancy test: For a pregnant lady, the blood pregnancy test will become positive 10 days after ovulation and fertilization or within 3-4 days of implantation.
- Urine Pregnancy Test: Normally a urine pregnancy test indicates positive only after the period has been missed or a week after implantation. Don't believe manufacturers who claim their urine pregnancy test gives results before a period has been missed; statistics prove otherwise.
The difference in various urine pregnancy tests regarding time taken to turn positive can be attributed to the following four factors:
1. The implantation time
The presence of the pregnancy hormone hCG (human chorionic gonadotropin) in blood or urine is detected by a pregnancy test. The hCG first enters the blood, then it comes into the urine after passing through the kidney. Post ovulation when the egg is fertilized, it travels to the uterus through the fallopian tube for about a week. The fertilized egg gets attached in the uterus a week after ovulation / fertilization. This is known as implantation. This process can take anywhere between six to 12 days in most cases. Once implantation has occurred, the placenta starts producing the hCG hormone, which then enters the blood stream. The blood stream presence of hCG can be detected 4 days after implantation. 2 to 3 days after hCG has been detected in the blood, it can be seen in the urine as well. Thus detection of blood hCG depends on the implantation time. 9 to 16 days after ovulation, hCG can be seen in the blood.
2. The amount of hCG in blood
There is a huge difference in the hCG levels found in blood and urine. For a woman having low hCG level in the blood, it can take longer for the hCG to show up in the pregnancy test.
3. The level of hCG in urine
The level of hCG in your urine is different at different times of the day depending on your liquid intake and the concentration of urine. It is best to take a urine pregnancy test with highly concentrated urine. Greater intake of fluid makes the urine more diluted which will affect the quantity of hCG required in order to get a positive result on the pregnancy test.
4. How sensitive is your home urine pregnancy test?
The sensitivity of a pregnancy test differs based on the brand. For a pregnancy test to become positive quicker, it must have a low sensitivity. Sensitivity is measured in mIU/mL, which is the least quantity of hCG for the urine to test positive. A pregnancy test having a sensitivity of 20 mIU/mL will take half the amount of hCG level as compared to a pregnancy test having a sensitivity of 40 mIU/mL. Also the former pregnancy test will test positive several days earlier than the latter which has a high sensitivity. Read through the packaging of your pregnancy test to get an idea of its sensitivity before purchasing it.