When should you take a pregnancy test?
For the most accurate result, take a home pregnancy test on the first day of your missed period or later. If you don’t know when your period is due, test 21 days after unprotected sex.
Pregnancy tests look for human chorionic gonadotropin (hCG), a hormone your body only starts making after a fertilized egg implants in the uterus. Implantation happens 6–12 days after ovulation — most often on days 8–10 — and hCG then needs a few days to build up to a level a urine test can detect. Testing before that point can’t show a positive, even if you are pregnant.
Testing day by day after ovulation
“DPO” means days past ovulation. Here’s what to expect in a typical 28-day cycle, where your period is due 14 days after ovulation:
| Days past ovulation | What’s happening | Should you test? |
|---|---|---|
| 0–5 DPO | Fertilization and early cell division; the embryo travels to the uterus | No — no hCG yet |
| 6–9 DPO | Implantation usually happens; hCG production begins | Too early for most tests |
| 10–12 DPO | hCG rising, roughly doubling every 2–3 days | Early-result tests may turn positive; many will still be negative |
| 13 DPO | Day before your expected period | Reasonable chance of a positive, but a negative isn’t final |
| 14+ DPO | Missed period | Best time to test — most tests are reliable |
Not sure when you ovulated? Our ovulation calculator estimates it from your cycle.
How home pregnancy tests work
Home tests use antibodies that change color when urine contains hCG above a set threshold. “Early result” tests have a lower threshold, so they can turn positive a few days sooner — but research has found that many tests marketed this way do not detect the low hCG levels present in early pregnancy. The FDA advises that for the most reliable result you test 1–2 weeks after a missed period, and retest after a few days if the first result is negative.
A blood test at your doctor’s office measures the exact amount of hCG and can detect pregnancy slightly earlier. It’s also used to check that hCG levels are rising normally.
How to get the most accurate result
- Wait until your period is late if you can.
- Use first-morning urine when testing early — it has the highest hCG concentration.
- Don’t drink large amounts of fluid just before testing.
- Follow the instructions exactly and read the result within the stated time window. A faint line inside the window usually still means pregnant.
- Negative but no period? Test again in 2–3 days. If you keep getting negatives and your period is more than a week late, contact your doctor.
What to do after a positive test
Congratulations! Start taking a prenatal vitamin with folic acid if you aren’t already, and contact your doctor or midwife to book your first prenatal visit — usually around 8 weeks of pregnancy. Use the pregnancy calculator to see how many weeks pregnant you are, and the due date calculator to estimate when your baby will arrive.
Seek urgent medical care if you have a positive test and severe one-sided abdominal pain, shoulder pain, dizziness or heavy bleeding — these can be signs of an ectopic pregnancy.
Frequently asked questions
When is the earliest I can take a pregnancy test?
Some sensitive home tests can pick up pregnancy hormone (hCG) about 10 days after ovulation — roughly 4 days before a missed period in a 28-day cycle. Testing that early often gives a false negative, so if it’s negative, test again on the day your period is due.
How many days after sex should I take a pregnancy test?
If you don’t know when your period is due, wait at least 21 days after unprotected sex for a reliable result. If you track your cycle, test from the first day of your missed period.
Is it better to test in the morning?
Early on, yes. First-morning urine is the most concentrated, so it contains the most hCG. From the day of your missed period onward, most tests work at any time of day — just avoid drinking lots of fluid right before testing.
Can a pregnancy test be negative if I’m pregnant?
Yes. A false negative usually means you tested too early, used diluted urine, or ovulated later than you thought. If your period still hasn’t come, wait 2–3 days and test again, or ask your doctor for a blood test.
Can a pregnancy test give a false positive?
It’s uncommon. Causes include a very early pregnancy loss (chemical pregnancy), recent pregnancy or miscarriage, fertility medicines containing hCG, reading the result after the time limit, and some rare medical conditions.
Are blood tests more accurate than home tests?
A blood test from your doctor can detect smaller amounts of hCG and measure the exact level, so it can confirm pregnancy a little earlier. Home urine tests become more reliable each day after a missed period; the FDA suggests 1–2 weeks after a missed period for the most reliable result.
Sources
- Wilcox AJ, Baird DD, Weinberg CR. Time of implantation of the conceptus and loss of pregnancy. N Engl J Med 1999;340:1796–9
- U.S. Food & Drug Administration — Pregnancy (home use tests)
- NHS — Doing a pregnancy test
- Cole LA et al. Accuracy of home pregnancy tests at the time of missed menses. Am J Obstet Gynecol 2004;190(1):100–5
- MedlinePlus — Pregnancy test