Fetus At 8 Weeks Heartbeat | What The Scan Really Shows

Reaching the point where early cardiac activity is visible on a screen can feel both thrilling and nerve-wracking. You might walk into the appointment hoping to see a clear flicker and hear a number that makes sense, while also worrying about what happens if the machine stays quiet. Understanding what a heartbeat at this stage usually means, how it is measured, and why results sometimes differ can make that visit easier to process.

This guide walks through how the heart forms in early pregnancy, what a typical scan at eight weeks shows, how heart rate ranges change by week, and when differences from those ranges might lead a doctor to suggest follow-up. Along the way you will see where expert groups and medical organizations place the usual milestones so you can match what you heard in the exam room with clear reference points.

How Early Cardiac Activity Develops

During the first weeks after conception, the structure that later becomes the heart changes fast. Cells in the middle of the embryo form a simple tube. That tube begins to contract rhythmically, long before there is a four-chambered organ that looks like the image many people picture when they hear the word “heart.”

On a high-quality transvaginal ultrasound, rhythmic motion in this region can sometimes be seen as early as five to six weeks of gestation, measured from the first day of the last menstrual period. At that stage, specialists often use terms such as “cardiac activity” rather than “heartbeat” because the organ is still in an early structural phase. Medical references describe this early motion as tissue that will later remodel into a more familiar shape rather than a finished organ beating inside the chest.

Timeline From Five To Nine Weeks

From a parent’s point of view, the practical question is simple: when can a scan usually pick up that flicker? The answer depends on both timing and equipment. Many sources note that motion in the cardiac tissue can often be detected by ultrasound around weeks five to six of pregnancy, though not every scan will show it that early.

By around week eight, most embryos are large enough that a transvaginal scan can show clear cardiac activity when the pregnancy is developing on track and the dates are accurate. With abdominal ultrasound, the picture may not be as sharp, so some people still need a few more weeks before motion can be seen with that method alone.

What The Fetus Looks Like At Eight Weeks

At eight weeks of pregnancy, medical sites describe the embryo or fetus as roughly the size of a raspberry, often in the range of 11 to 14 millimeters from crown to rump. The head remains large compared with the body, limb buds are lengthening into arms and legs, and early facial features such as the nose and eyes are forming.

Inside the chest, the early heart structure has started to divide into chambers and is already pumping blood through tiny vessels. That activity helps drive the growth of organs and tissues across the rest of the body.

Normal Heart Rate Range At Eight Weeks

The number that often stands out on the screen is the beats per minute (BPM). Early in the first trimester, the rate climbs as the weeks pass. Research on early pregnancy ultrasound shows that the average rate often rises from around 110 BPM in the early sixth week to near the high 150s by about seven and a half to eight weeks.

Many clinical summaries describe a common heart rate range near 140 to 170 BPM at eight weeks, though individual readings can fall outside those numbers and still align with healthy development. What matters more than a single number is the broader pattern: whether the rate fits the gestational age, whether it is steady, and whether the embryo’s size matches the dates based on the last menstrual period.

Heart Rate Changes Week By Week

The chart below pulls together common ranges reported in medical reviews and patient-facing education pages. It is not a substitute for your clinician’s interpretation, but it helps show how fast things change in a short span of time.

Gestational Week	Typical Crown–Rump Length	Usual Heart Rate Range (BPM)
5 Weeks	1–4 mm	90–110
6 Weeks	4–8 mm	110–130
7 Weeks	8–11 mm	130–150
8 Weeks	11–14 mm	140–170
9 Weeks	14–20 mm	140–170
10 Weeks	20–30 mm	140–170
11–12 Weeks	30–50 mm	120–160

These numbers reflect ranges rather than hard limits. A reading slightly outside the bands in this table can still match a healthy pregnancy. When a rate is far below or above the expected span, the sonographer or doctor looks at that information alongside other details such as the embryo’s size, growth from a prior scan, and the presence of any symptoms.

Some studies and hospital patient leaflets note that once a strong heartbeat is seen at around eight weeks, the chance of the pregnancy continuing rises sharply. One National Health Service leaflet cites data where a visible heartbeat at this stage was linked with about a 98 percent chance of the pregnancy ongoing.

Fetus At 8 Weeks Heartbeat On Ultrasound: What You Usually See

During an early scan at this stage, the sonographer first confirms that the pregnancy is in the uterus and checks the number of embryos. The screen then zooms in on the gestational sac and the small fetus curled inside. Cardiac activity appears as a flickering area in the chest region. With Doppler turned off to limit exposure in line with safety guidance, the machine uses M-mode or B-mode to trace the motion and calculate a heart rate.

In many clinics, a transvaginal probe gives the clearest picture at eight weeks. The probe sits closer to the uterus, so it can pick up finer detail in a small structure. Some providers switch to an abdominal scan once the image quality is strong enough or if the patient prefers that approach and the view is adequate. Guidance from organizations such as the American Institute of Ultrasound in Medicine explains that early scans should use the lowest output settings needed to answer the medical question, which keeps exposure time short while still showing the heart motion clearly.

What The Sonographer Measures

When the flicker is visible, the person performing the scan may either freeze the image in M-mode to draw a line through the moving heart region or use software that tracks the motion over several beats. The machine then reports a BPM reading.

Along with heart rate, the scan usually includes a crown–rump length measurement. That distance from the top of the head to the bottom of the torso gives a gestational age estimate. Medical education sites such as the Mayo Clinic first trimester fetal development overview and resources from large hospital systems describe how these measurements line up with the expected pace of organ and limb growth.

For many parents, seeing both a heartbeat and a crown–rump length that fits the expected week of pregnancy brings a sense of relief. Even so, it helps to remember that a single scan is one piece of information. Follow-up appointments and later ultrasounds add context.

Hearing The Heartbeat At Eight Weeks

In some clinics, audio playback is available during the scan. Other providers wait until later in the first trimester to turn on sound, since guidelines suggest keeping energy exposure as low as reasonably achievable while measurements are taken. Educational pages from pregnancy and health sites explain that an ultrasound is more reliable than a hand-held Doppler device for detecting early cardiac activity at eight weeks, so it is common for a Doppler not to pick up sound even when a scan shows steady motion.

Why Heartbeat Detection At Eight Weeks Can Differ

Not every eight-week scan leads to a neat, easy reading. You might hear that the embryo is measuring smaller or larger than the dates, that the rate is slower or faster than expected, or that no cardiac activity is visible yet. Several factors can shape what shows up on the screen.

Dating Differences

One of the most common reasons for a scan that seems “behind” is that the pregnancy is earlier than the calendar suggests. Ovulation does not always match the textbook day, and implantation can vary as well. If conception occurred later in the cycle, the embryo may still be too small at what looks like eight weeks by dates. In that case, heart motion may appear a few days or a week later.

Medical articles that describe early heartbeat timing point out that some pregnancies do not show clear activity until near the eighth week even when everything progresses normally. A review in Medical News Today on early cardiac activity notes that detection usually occurs around weeks five to six but can be delayed in some cases without indicating a problem.

Technical And Physical Factors

Image quality depends on more than gestational age. The position of the uterus, the angle of the probe, the presence of fibroids or other structures, and the patient’s body size can all shape what the sonographer sees. A full or empty bladder can change the view on an abdominal scan. Switching to a transvaginal probe or repeating the exam after a short interval can sometimes bring a clearer image.

Machine settings matter as well. Radiology practice documents remind clinicians to keep thermal and mechanical indexes within recommended ranges and to shorten scan time when measuring cardiac activity, which also influences how long the sonographer spends capturing that flicker.

Embryo Growth Patterns

In some pregnancies, the embryo measures smaller than expected or the heart rate falls well below the common range for the week. Studies of early first-trimester scans link clearly low rates with a higher chance of early pregnancy loss, and outcomes still vary from case to case. Professional bodies such as the American College of Obstetricians and Gynecologists advise doctors to use strict criteria before diagnosing pregnancy loss on ultrasound and often recommend repeat scans to confirm any finding that suggests a non-viable pregnancy.

If you receive news that the rate is lower than expected or that no heartbeat is visible yet, a follow-up scan is usually scheduled after a set number of days. That second scan helps show whether there has been growth and whether cardiac activity appears or changes over time.

Common 8 Week Heartbeat Scan Results And Next Steps

To put the range of possible outcomes in one place, the table below shows scenarios many people hear at this stage and the usual next step a clinician might suggest. This is a general overview rather than a rulebook, since each person’s medical history and symptoms change the plan.

Scan Finding At Around 8 Weeks	What It Can Mean	Typical Next Step
Clear cardiac activity, rate in common range	Development appears to match gestational age.	Routine prenatal care and later dating or screening scans.
Clear cardiac activity, rate slightly outside range	Variation that may still fit a healthy pattern.	Clinician may repeat scan or check rate at a later visit.
No heartbeat seen, embryo small for dates	Pregnancy may be earlier than estimated or may not be progressing.	Repeat scan after 7–10 days to check for growth and new activity.
No heartbeat seen, embryo size suggests 8 weeks or more	Could indicate early pregnancy loss once strict criteria are met.	Doctor reviews options and may repeat scan to confirm findings.
Gestational sac seen, no embryo yet	Dates may be early or pregnancy may not be continuing.	Follow-up scan and blood tests to track hormone levels.
Twins with one or both showing cardiac activity	Multiple pregnancy with its own monitoring plan.	Referral or closer follow-up based on local protocols.
Heartbeat seen plus bleeding or pain	Pregnancy may still continue, though symptoms need assessment.	Doctor evaluates for causes such as subchorionic hematoma or ectopic pregnancy.

When reading your report later, it can help to look for three main pieces: the documented heart rate, the crown–rump length and estimated gestational age, and any comments about the sac, yolk sac, or surrounding structures. Together they give a fuller picture than the BPM on its own.

When To Call Your Doctor Or Midwife

While many eight-week scans bring reassuring news, some symptoms call for prompt medical advice. If you notice heavy bleeding, severe abdominal pain, fainting, or shoulder pain, contact your pregnancy care provider or emergency services without delay. Even with a recent scan that showed cardiac activity, new or worsening symptoms need attention.

Outside urgent situations, it still makes sense to reach out if scan results leave you confused or worried. Asking your clinician to walk through what the report means and how it fits your overall health history can make the next steps much clearer. Bringing written questions to the next visit often helps you leave with fewer loose ends.

Eight Week Fetal Heartbeat And Emotional Reactions

Hearing the first steady rhythm can bring joy, relief, or tears. For someone who has lived through pregnancy loss or fertility treatment, it may also stir fear about what upcoming scans might show. These reactions all fit within a wide range of normal feelings at this stage.

If you feel overwhelmed, it can help to share those thoughts with a trusted person in your life or with a counselor who has experience with pregnancy-related concerns. Reading balanced medical information from trusted sources, such as NHS week-by-week pregnancy guides or patient pages on early ultrasound from your local hospital, can also anchor your expectations.

Caring For Yourself While You Wait Between Scans

Early pregnancy comes with many questions that no test can answer in advance. While you wait for follow-up appointments or later scans, small daily habits can help you feel a bit more grounded.

Stay Connected With Your Care Team

Know how to reach your clinic after hours and which symptoms should prompt a call. Many practices offer nurse advice lines or secure messaging portals, which can be a good place to ask practical questions about medications, activity levels, and later appointments.

Use Trusted Information Sources

Sticking with reputable health sites reduces the chance of running into misleading claims about early heartbeat timing or miscarriage risk. Large organizations such as the American College of Obstetricians and Gynecologists bulletin on early pregnancy loss and the AIUM statement on prudent ultrasound use publish guidance aimed at clinicians but also helpful for patients who want to see how decisions are made.

Protect Your Physical And Emotional Health

Rest when you can, follow the prenatal care plan suggested by your clinician, and seek help if anxiety or low mood start to interfere with sleep, appetite, or daily activities. Mental health professionals who work with people in the perinatal period can offer tools to manage worry around appointments and scan results.