At first, it’s just two cells.

Then something miraculous happens.

A flicker. A rhythm. A signal that life is underway.

For expectant parents, that first heartbeat is more than just a medical milestone. It’s a moment of wonder. A confirmation. A beginning.

But when exactly does it happen?

Let’s break down what science knows, what doctors say, and what it means for you—week by week.

Why The Fetal Heartbeat Matters More Than You Think

The fetal heartbeat is more than a diagnostic tool.

It’s emotional reassurance. It’s clinical data. And it’s symbolic of progress in early pregnancy.

• It tells us the pregnancy is developing inside the uterus (not ectopically).

• It confirms gestational age.

• It reassures hopeful parents that something real and rhythmic is happening.

In fact, for many families in Parentune's community, hearing that tiny heartbeat is when the pregnancy starts to feel real.

Week-By-Week Breakdown: When The Heart Starts Beating

Let’s be precise. Because nature is both poetic and scientific.

Week 3–4: The Blueprint Begins

No heartbeat yet—but the foundations are being laid.

This is when:

• The fertilized egg implants in the uterus.

• The embryo begins forming the primitive streak—the earliest sign of the future nervous system and heart.

• The yolk sac supports early growth.

Think of this stage as the construction of electrical wiring before the lights can turn on.

You may also like to read:

Baby’s Heartbeat: What You Need to Know

Week 5: The First Flicker

By the fifth week of pregnancy (about three weeks after conception), the fetal heart tube forms.

It doesn’t look like a heart yet.

But it begins to pulsate—irregularly, like a learning drummer. Around 100–110 beats per minute.

This may be detectable via a transvaginal ultrasound, though not always.

Here’s the catch: This flicker isn’t always visible in week 5. And that’s okay.

Week 6: The Beat Becomes Stronger

Week 6 is when many parents first see and hear the heartbeat on ultrasound.

The fetal heart now beats between 110–160 bpm and is steadily developing chambers.

This is typically the first time your OB-GYN will confirm "a viable heartbeat."

It's also the week when miscarriage risk drops dramatically if a heartbeat is detected.

Week 7–8: A Heart Takes Shape

By this stage:

• The heart has distinct right and left chambers.

• The rhythm becomes more regular.

• The baby is still just 1–2 cm long, but the heart is fully functional.

This is also when most non-invasive ultrasounds (like abdominal scans) can pick up the heartbeat—especially with newer machines.

How Is the Fetal Heartbeat Detected? Tools & Timing

Different tools, different timings. Here's what expectant parents should know.

1. Transvaginal Ultrasound

• Used between 5–8 weeks

• Most accurate for early heartbeat detection

• Inserted through the vagina, not painful but mildly uncomfortable

Also read:

Ultrasound Scans During Pregnancy: Know When & Why You Need Them

2. Abdominal Ultrasound

• Common after 8 weeks

• Uses a gel and external probe

• Less precise early on, but standard for most follow-ups

3. Doppler Fetal Monitor

• Detects heartbeat from 10–12 weeks onwards

• Not typically used in early scans

• More for reassurance between checkups

Watch an exclusive workshop on Fetal Heart Rate during Pregnancy: What is normal?

What If The Heartbeat Isn’t Found Yet?

This is the part most expectant parents fear.

Silence.

But here’s what experienced OBs will tell you: Don't panic too soon.

There are three main reasons a heartbeat isn’t detected early:

1. You’re earlier than you think. Conception dates can be off by a few days or more.

2. Your uterus is tilted. Anatomical differences affect visibility.

3. The equipment matters. Not all ultrasound machines are equally sensitive.

Doctors often recommend a follow-up scan in 7–10 days before drawing conclusions.

In most Parentune community stories, early absence of heartbeat is resolved in the next scan.

Heartbeat Timeline Cheat Sheet

Bookmark this table. Print it if you like. It’s a reference worth keeping handy.

Why Heartbeat ≠ Heart Health (Yet)

It’s easy to assume that a heartbeat means everything is fine.

And mostly, that’s true.

But early cardiac activity doesn’t rule out:

• Structural issues (e.g., congenital heart defects)

• Chromosomal abnormalities

• Growth concerns later in pregnancy

That’s why detailed anomaly scans at 18–22 weeks are still vital.

Early heartbeat is a green flag, not a full clearance.

What Can Affect A Fetus’s Heartbeat?

Like any rhythm, the fetal heartbeat can speed up, slow down, or skip depending on various factors.

Common influences:

• Mother’s health: Fever, infections, thyroid

• Medications: Especially those that affect blood flow

• Stress levels: Elevated cortisol can have indirect effects

• Fetal movement: Increases during kicks or turns

• Placental function: A sluggish placenta can alter heart rate

Your doctor tracks not just the presence of a heartbeat—but its pace, rhythm, and resilience.

Parentune’s Perspective: Heartbeat And Beyond

Heartbeat is just the beginning of a journey that’s deeply emotional and medically monitored.

But in the sea of internet noise, finding the right kind of information—backed by experts, grounded in empathy—isn’t easy.

That’s why thousands of expecting parents trust Parentune.

At Parentune:

• Every article is reviewed by OB-GYNs and pediatricians.

• Every insight is cross-validated by a real parent community.

• Every heartbeat story is treated with the care it deserves.

Because in this phase, you don’t just need facts—you need perspective, community, and calm.\

Final Word: A Beat That Starts It All

The fetal heartbeat starts as a tiny flicker.

By week 6, it’s a symphony of hope.

But what makes it truly powerful isn’t just biology—it’s what it represents: the beginning of a shared story, a new chapter, a heartbeat that’s no longer just your own.

For every expectant parent reading this, know this:

• Your questions are valid.

• Your worries are common.

• Your experience is shared—by millions navigating pregnancy just like you.

And in places like Parentune, you’ll always find support, science, and solidarity.