That two-week wait after trying to conceive can feel endless. Whether you're trying for the first time or have been on this path for a while, knowing when to take a pregnancy test (and when to trust the result) makes the real difference.

How does a pregnancy test actually work?

All pregnancy tests detect the hormone Human Chorionic Gonadotrophin (hCG), which starts to be produced around 6 days after fertilisation.1 As the pregnancy progresses, hCG levels rise. Waiting closer to your missed period gives it more time to accumulate, so there's enough in your system for the test to detect reliably.

Most kits give you one or two test sticks. You pee on the stick, then wait a few minutes for the result to appear. The exact process varies by brand, so it's worth a quick read of the instructions before you begin.

The right time to take a pregnancy test

After a missed period

Most pregnancy tests can be done from the first day of a missed period. This is the most reliable window. By this point, if you're pregnant, your body has had enough time to build up a detectable level of the hormone that pregnancy tests look out for.

If your cycles are irregular and you're not sure when your period was due, that's okay — there's still a clear guideline to follow:

After unprotected sex (if you're unsure of your cycle)

If you don't know when your next period is due, wait at least 21 days from your last unprotected sex before testing. Testing before that point increases the risk of a false negative; not because the test is faulty, but because the hormone it detects hasn't had time to build up enough to register in your system.

Can you test earlier than that?

Some very sensitive pregnancy tests can be used even before you miss a period. These are sometimes marketed as "early response" tests. They can detect lower levels of hCG, but the earlier you test, the higher the chance of a false negative if you are in the very early stages of pregnancy.

If you test early and get a negative result, it's worth testing again once your period is due, or a few days after if it still hasn't arrived.

Factors that affect pregnancy test results

Time of day

It’s not necessary that you take the test in the morning. You can do the test on a sample of urine collected at any time of the day; that said, if you're testing early — before or just around your missed period — first morning urine tends to be more concentrated, which can make it easier for a sensitive test to detect hCG. If you're testing at or after your missed period, the time of day matters less.

Following the instructions

Each test works slightly differently. Skipping a step or misreading the line is one of the most common reasons people get a misleading result.

Testing too early

The earlier you test, the less hCG is in your system. Even a sensitive test can miss a pregnancy if there isn't enough hormone to detect yet. If you're testing before your missed period, a negative result doesn't always mean you're not pregnant. It may just mean it's too soon.

Certain medications

Some medicines can affect the results. If you're taking any medication and are unsure whether it could interfere, check with your GP or pharmacist before testing.

Different ways to take a pregnancy test in the UK

At-home urine test (pharmacy or supermarket)

This is the most common route. You can buy pregnancy testing kits from pharmacists and some supermarkets. They give a quick result and you can do the test in private. Most kits contain one or two sticks, and results typically appear within a few minutes.

Free testing through the NHS

Free options include sexual health services, some young people's services (call the national sexual health helpline on 0300 123 7123 for details), and Brook centres if you're under 25. Your GP may also be able to assist you with pregnancy tests. 

Blood test at your GP or clinic

A blood test can detect hCG earlier than a urine test, and can also measure the exact level of the hormone, which is useful if your GP wants to monitor early pregnancy or investigate an unusual result. You'd need to book an appointment with your GP or a sexual health clinic to access this.

At-home pregnancy test kit: twoplus Fertility

If you're actively trying to conceive, having tests at home and ready to use is often the most practical option. The twoplus Fertility pregnancy test kit is designed for home use, giving you a clear result without a trip to the pharmacy. It may be a convenient option if you're in an active trying-to-conceive (TTC) cycle and want to test at the right moment, on your own schedule.

Get your pregnancy test kit now!

How accurate are home pregnancy tests?

Used correctly, home pregnancy tests are completely reliable. Although a positive result is almost certainly right, a negative result is more likely to be wrong — usually because of timing, not a faulty test.

In other words: a positive is a positive. A negative is worth double-checking if your period still hasn't arrived.

Why might a negative result be wrong?

The result may not be reliable if you do not follow the instructions properly, or if you take the test too early. Some medicines can also affect the results. If you’re still doubtful, wait a few days and try again. Speak to your GP if you get a negative result after a second test but your period has not arrived.

What about testing if you're on the pill?

Contraceptive hormones, including the pill, don't interfere with a pregnancy test. The test looks for hCG specifically, and hormonal contraception doesn't affect that. 

In summary: when is the best time to take a pregnancy test?

The most reliable result comes from waiting until your period is due. Testing earlier is possible with sensitive tests, but comes with a higher chance of a false negative.

Still trying to conceive?

If your test comes back negative and you're actively trying to get pregnant, it can feel deflating — but a negative result doesn't mean something is wrong. Timing plays a big role, and there are practical steps that can support your efforts each cycle: 

Understanding your fertile window:

Knowing when you ovulate is one of the most important things you can do when trying to conceive. Ovulation typically happens around the middle of your cycle, and you're most likely to conceive in the few days leading up to it.

An ovulation test kit can help you identify your most fertile days, so you can time things more precisely rather than guessing.

Supporting sperm delivery at home:

For couples where timing or sperm motility is part of the picture, some choose to use a home insemination kit as part of their conception routine. 

Twoplus Fertility: Supporting couples trying to conceive

Trying to conceive can quickly start to feel like a chore. Timed sex, misaligned schedules, and even performance pressure often add up. The twoplus Applicator Extra takes that pressure off, so every fertile window becomes an opportunity again, not an obligation.

The twoplus Applicator Extra is a self-assisted artificial insemination kit that can be used from the comfort of your home. In just 3 simple steps, the Applicator Extra helps deposit sperm close to the cervix, giving nature a helping hand.

• No medical help or clinic visit needed

• Deposits semen close to the cervix, giving sperm a more direct path

• Designed for comfort with soft tip made of 100% medical grade silicone 

• Make your fertile window count

• Affordable alternative to try now: 3 steps. 15 minutes

Sources:

1. NHS – Doing a pregnancy test