You’ve taken a home pregnancy test and seen those magical two lines. Congratulations, mama – you’re pregnant!
Now it’s time to confirm the happy news with your doctor. But when you get to your first prenatal appointment, they may recommend getting a blood test done as well.
You might wonder why you need a blood pregnancy test when you’ve already peed on the stick. What additional information could it give?
As it turns out, blood tests provide doctors with useful insights into your pregnancy from the very start. Here’s what you need to know about this important prenatal screening.
How Does a Blood Pregnancy Test Work?
A blood pregnancy test detects the presence and levels of a hormone called human chorionic gonadotropin (hCG). This hormone is produced by the placenta shortly after the fertilised egg implants in your uterus.
HCG levels rise rapidly in the first few weeks of pregnancy, doubling every 48-72 hours. This quick increase signals to your body that you’re pregnant so it can start supporting the developing embryo.
A blood test measures the concentration of hCG in your bloodstream. Even tiny amounts can be detected as early as 6-8 days after conception.
There Are Two Main Types of Blood Pregnancy Tests
Qualitative hCG Test
This is a simple yes or no detection of hCG. It’s like a home pregnancy test, but using a blood sample rather than urine. It can tell if you’re pregnant or not.
Quantitative hCG Test
Also called a beta hCG test. This measures the exact amount of hCG present. It not only confirms pregnancy, but provides additional details.
Doctors may order:
- A single quantitative test to see if hCG levels are within the normal range for your stage of pregnancy.
- Two separate tests done 2-3 days apart to check if your hCG is rising appropriately. Doubling every 48-72 hours is considered normal progress in early pregnancy.
- Multiple beta hCG tests throughout the first trimester to ensure your levels follow the expected pattern of rapid increase followed by a decline and plateau.
A Blood Test Can Detect Pregnancy Earlier
Home urine pregnancy tests look for hCG levels of 25 mIU/mL or higher. But a blood test can detect hCG at just 5-10 mIU/mL.
This means pregnancy can be confirmed by blood as early as 6-8 days after fertilisation. Whereas urine tests don’t typically turn positive until 10-14 days after conception.
If you’re anxious to know, the extra sensitivity of a blood draw could give you peace of mind a few days sooner.
Blood Tests Are More Accurate
When performed at the appropriate time, blood pregnancy tests are over 99% accurate.
There’s less chance of getting a false negative than with a urine test, especially if you take it too early.
Blood tests are also less likely to give a false positive result. Situations that can cause a urine test to show positive when you’re not actually pregnant are unlikely to affect a blood draw.
That said, no test is 100% foolproof every time. The results should be considered along with your full health picture.
A Quantitative Test Provides Insight Into Your Pregnancy
While a qualitative blood test simply gives a yes or no answer, a quantitative hCG test offers much more:
Estimate Gestational Age
By assessing your exact hCG levels, your doctor may be able to calculate how far along you are. This gives them an estimate of when to expect your due date.
Check for Multiple Gestations
Significantly higher than average hCG levels can indicate you may be carrying twins or triplets!
Spot Potential Issues
Low hCG levels or inadequate doubling times could signal an increased risk of miscarriage or ectopic pregnancy. Follow up testing and monitoring would be recommended.
On the other hand, perfectly normal results provide peace of mind that your pregnancy is progressing well.
Diagnose Pregnancy of Unknown Location
If you have positive pregnancy blood work but no visible foetus on ultrasound, it’s known as a pregnancy of unknown location. Quantitative hCG values help determine appropriate next steps.
Confirm Pregnancy Loss
Slowly dropping hCG levels indicate that a pregnancy is not viable. Your doctor can use blood work to monitor until levels return to zero.
Rule Out Pseudocyesis
In rare cases, a false belief of being pregnant causes physical signs and symptoms. Blood tests confirm if a pregnancy is real or not.
Reasons Your Doctor May Order a Blood Test
Beyond verifying a home pregnancy test, here are some specific reasons for getting a blood draw:
- You need proof of pregnancy for medical documentation
- You have signs of an ectopic pregnancy
- You’ve had previous miscarriages
- You underwent fertility assistance to get pregnant
- You’re uncertain on dates of possible conception
- You need noninvasive prenatal testing (NIPT)
- You have vaginal bleeding or cramping
- You’ve received hCG medication or injections
If you’ve had positive home pregnancy tests, your doctor may not order bloods unless medically indicated. Qualitative urine and blood results are generally comparable.
But if you are high risk or have specific pregnancy concerns, a quantitative hCG is very useful for monitoring your early progress.
What to Expect When Getting Blood Drawn
Although home urine testing is simpler, having blood drawn is quick and minimal discomfort.
- No eating or drinking beforehand
- The area, usually the inside of your arm, will be cleaned
- A tourniquet is applied to plump up your vein
- You may feel a slight pinch or sting as the needle goes in
- A small tube attached collects the blood sample
- Pressure is applied after the needle is removed to prevent bruising
- The whole process takes just a few minutes
Let your phlebotomist know if you have anxiety around blood draws. They can help with techniques to make it easier for you.
Waiting for Results
Depending on the type of test ordered by your doctor, results will be available in 1-3 days. Some clinics can process stat quantitative tests in just a few hours if urgent.
Try to be patient – worrying never changes the outcome! Distract yourself with soothing music, go for a walk, or work on your pregnancy journal.
Celebrate once you get the call that your blood work came back confirming your pregnancy! Now you can start getting excited about what lies ahead.
Blood Testing Options in Early Pregnancy
Beyond hCG, your doctor may recommend additional blood screening at your first prenatal visit. Here are some of the possible tests:
Complete Blood Count (CBC) – Checks levels of your blood cells, identifies anaemia
Blood Type & Rh Factor – Determines your blood type (A, B, AB, or O) and Rh factor (positive or negative)
Rubella Immunity – Confirms you’re protected from rubella/German measles
Infectious Disease Screening – Tests for HIV, hepatitis, syphilis, and other infections
Chicken Pox Immunity – Checks if you’re immune to varicella zoster
Glucose Challenge Test – Screens for gestational diabetes later in pregnancy
Genetic Carrier Screening – Optional test for genetic diseases you could pass on
Noninvasive Prenatal Testing (NIPT) – Screens for chromosomal conditions
Blood work throughout pregnancy assists your medical team in keeping you and baby healthy. Always ask your doctor to explain why a test is recommended.
Blood Pregnancy Testing Is an Important Prenatal Tool
While home pregnancy tests serve their purpose, blood hCG testing offers definite advantages in specific situations. It can provide vital information to detect issues and ensure your pregnancy is on track.
Work with your doctor to determine if a blood test makes sense for your individual circumstances. If so, don’t stress about the needle – it’s quick and confirms you get to meet your little one in several months!
Photo by Anthony Cunningham for Zoom Baby