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Day 22 of 280 · 3 weeks + 1 day

The hormone that says yes

Last reviewed · 3 min read · 5 sources · Plain-text version

Once the egg implants, your body makes hCG, and it rises every day. It is what every pregnancy test looks for, and why the box says to wait.

Size this week
a single cell, then a ball of cells
A woman in her late twenties with red hair sitting on the edge of a bathtub, reading the folded paper leaflet from a small box, the test still sealed beside her, daylight.

Every pregnancy test, the cheap strip and the digital one, is looking for one thing. Today is what it is, when it shows up, and how to read a box properly.

Your baby

hCG, human chorionic gonadotropin, is formed when a fertilized egg implants in the uterus, and the level rises each day of pregnancy (Office on Women's Health). It is the first thing the ball of cells does that the outside world can detect: the cluster building the placenta (NICHD) is also sending a signal that something has taken hold.

Your body

Small amounts of hCG are present even before the first missed period, and the amount increases as pregnancy continues (NICHD). Home tests measure hCG in urine, and they detect it with up to 97% accuracy (NICHD). A side effect: hCG, produced in the first few weeks, increases blood flow to the pelvic region, which is why frequent urination is common (NICHD).

Most home tests don't give accurate results one day after a missed period; waiting one week after a missed period usually gives a more accurate result, and if a test is negative but your period hasn't come, repeat it after a week (Office on Women's Health). Some medicines can affect home test results (Office on Women's Health).

Try today

  1. The test-kit read-through

    Time: 5 minutes, before you open the test

    1. Read the leaflet, not the box front. Note the wait time; research suggests waiting 10 minutes for the most accurate result (Office on Women's Health).

    2. Plan the test for first thing in the morning, which may improve accuracy (Office on Women's Health).

    3. Find the control indicator in the diagram. If it does not appear, the test is not working (Office on Women's Health).

    4. If the result is positive, call your doctor right away to schedule an appointment; a more sensitive test and an exam can confirm it (Office on Women's Health; NICHD).

    Make it work:

    If you've already tested, do the read-through anyway and check the control line in your memory. A test with no control line was a non-answer, not a no.

Watch for

  • Normal

    a negative test taken a day after a missed period, which is often too early (Office on Women's Health).

    Call your provider

    if you've missed a period and tests stay negative; birth control pills, diabetes, PCOS, eating disorders, and certain medications can all stop a period (NICHD).

  • Normal

    a headache in the days before a period is due; headache, fatigue, and breast tenderness can all appear before a missed period (Office on Women's Health).

    Call your provider today

    for a headache that won't go away or gets worse over time, or for changes in your vision (CDC).

  • Normal

    running to the bathroom more than usual (NICHD).

    Call your provider today

    if severe nausea keeps you from drinking for more than 8 hours or eating for more than 24 (CDC).

For you

Blood tests can detect pregnancy about six to eight days after ovulation, earlier than urine tests (Office on Women's Health). A quantitative blood test measures the exact amount of hCG; a qualitative one gives a yes or no and is about as accurate as a urine test (Office on Women's Health). If you need to know sooner than a box can say, a provider can draw blood; otherwise the box, read properly, is enough.

The minute between the stick and the window is its own small country. If you're the partner, be in the room, or on the other end of the phone. A test is a fact, and facts are easier shared.

Sources

This guide is general education that summarizes published research and guidance from groups like the American Academy of Pediatrics, the CDC, and the WHO. It isn’t medical advice, and every child develops on their own timeline. Your pediatrician knows your child; if something feels wrong, call them. In an emergency, call 911.

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