When does cardiac activity start in pregnancy

If you've just received a positive pregnancy test, you probably have a lot of questions. From "when will I feel my baby kicking" to "when does morning sickness end," you (likely) have a lot on your mind. But if you're wondering when you'll hear your baby's heartbeat, fear not: The answer may be sooner than you think.

In fact, the "whoosh whoosh" of your little one's earliest cardiac activity is one of the first things doctors look and listen for. This early heartbeat may first be detected by a vaginal ultrasound as early as 5 1/2 to 6 weeks.

Here's everything you need to know about your baby's heartbeat, from how it's monitored to when you can hear it.

When Does a Baby Have a Heartbeat?

Embryonic cardiac activity (that is, the earliest pulses of what will become your baby's cardiac cells) begins approximately 22 days after conception. This initial "heartbeat" won't be detectable yet—even though it's pulsing an average of 110 times a minute. But thanks to ultrasound technology, you (and your doctor) should be able to hear your baby's heartbeat soon.

When Can You Hear a Baby's Heartbeat?

The earliest your baby's cardiac activity can be detected is between five and six weeks gestation. At this early stage in your baby's development, you will actually be seeing the "heartbeat" through an ultrasound image rather than hearing it through a Doppler. This is because your baby is so small that your doctor can only detect the electrical activity through ultrasound.

The ultrasound machine may add sound so you can hear it, but you will also be able to see the fast flicker of the cardiac cells communicating with one another.

If you don't see a heartbeat on the screen at your first visit, don't panic. It could still be too early, especially if you miscalculated how far along you are (which can happen if you have longer-than-normal menstrual cycles). It is because of this common issue that many expectant parents don't see their doctor for an ultrasound until they're a bit farther along in their pregnancies.

How Is Baby's Heartbeat Monitored?

There are numerous ways to detect and/or monitor baby's heartbeat. Early on, most doctors use transvaginal ultrasounds. These wand-like instruments do an internal scan of your organs, including your uterus—or womb. As your pregnancy progresses, doctors tend to use fetal Dopplers, as these handheld devices can detect your baby's heartbeat as early as 8 weeks. Regular ultrasounds may also be used.

Can You Hear Baby's Heartbeat With a Stethoscope?

The short answer is yes, but not at first. A baby's heartbeat cannot be detected with a stethoscope until they are 18 to 20 weeks. Since stethoscopes amplify internal noises, specifically for and of the heart and lungs, you can hear baby's heartbeat using a stethoscope. However, detecting baby's heartbeat using the method is more challenging than with a fetal Doppler. It will also take patience and time.

Is There an App to Hear Baby's Heartbeat?

While the best method for measuring a baby's heartbeat is a fetal Doppler, apps like My Baby Heartbeat and BabyDoppler can help you monitor, track, and record the sound of your little one's little organ. That said, it's important to note that these apps are not 100% accurate. It is not recommended to use any apps as a replacement for an actual checkup—and you should meet with your health care provider first.

The Supreme Court is expected to overturn Roe v. Wade, the 1973 decision that guaranteed access to an abortion, according to a leaked draft opinion published by Politico on Monday.

The court confirmed in a statement on Tuesday that the though the draft was “authentic, it does not represent a decision by the court or the final position of any member on the issues in the case.” 

The leak comes as states have become increasingly bold in restricting access to abortion. Many have drawn the line at around six weeks of pregnancy — the point at which, the laws say, a so-called fetal heartbeat can be detected.

Full coverage of abortion rights and the future of Roe v. Wade

But according to experts, the term “fetal heartbeat” is misleading and medically inaccurate.

“While the heart does begin to develop at around six weeks, at this point the heart as we know it does not yet exist,” said Dr. Ian Fraser Golding, a pediatric and fetal cardiologist at Rady Children’s Hospital San Diego. 

Instead, at six weeks, the embryo will develop a tube that generates sporadic electrical impulses that eventually coordinate into rhythmic pulses, he said. (Six weeks of pregnancy is closer to four weeks of actual development, because pregnancy is measured from the first day of a woman’s last period, before she is actually pregnant.)

That’s far from a fully formed heart, with four chambers and valves that pump blood throughout the body.

The correct medical term for what’s observed at this point is “cardiac activity,” said Dr. Sarah Prager, a professor of obstetrics and gynecology at University of Washington Medicine.

“It’s not until about 10 weeks that there is an actual structure that has four tubes and connects to the lungs and major vascular system like we would think of as a heart,” she said. 

It’s around 10 weeks of pregnancy that the embryo becomes a fetus. It remains a fetus until birth.

But defining a heartbeat is tricky even after 10 weeks, said Dr. Nisha Verma, an OB/GYN who spoke on behalf of the American College of Obstetrics and Gynecology, because the heart continues to develop over the course of the pregnancy. 

It’s not until around 17 to 20 weeks, when the four chambers of the heart have developed and can be detected on an ultrasound, that the term heartbeat is accurate, according to ACOG.

An emotional touchpoint 

While what exists at six weeks isn’t a beating heart, pregnant people hear something during an ultrasound early in pregnancy. 

“Medically speaking, when I put a stethoscope against a patient’s heart, that ‘lub dub’ sound is made by the opening and closing of the cardiac valve,” Verma said. “At six weeks, those valves don’t exist.” 

In fact, the sound pregnant people hear during ultrasounds at six weeks is entirely manufactured by the ultrasound machine, Verma said. “It’s an electrical pulse that’s translated into the sound we’re hearing from the ultrasound machine.” 

What’s more, the electrical pulse from the embryo almost always can be detected only by using a transvaginal ultrasound, and it doesn’t yet show up on an ultrasound of the mother’s abdomen. 

But that’s where how doctors talk to patients comes in, Verma said. Although she wouldn’t consider any embryo at six weeks to have a heartbeat, she said doctors use language that patients can connect with, which often isn’t medical language, and that the use of the language in a doctor’s office plays an important role in how doctors communicate with patients. 

For example, two doctors speaking to each other would use the term “myocardial infarction,” whereas a doctor speaking with a patient would use the term “heart attack.” 

“I think it’s OK for people with a desired pregnancy to go in at six weeks and see that flickering and feel connected to that as a heartbeat,” Verma said. “There’s no issue with using the term ‘heartbeat’ on its own. The issue is using that incorrect term to regulate the practice of medicine and impose these artificial time frames to regulate abortion. At the end of the day, an abortion is a decision that should be made between a patient and their health care provider.”

Prager said the language and technology used during pregnancy, even in the doctor’s office, was designed for people who want to continue their pregnancies.

“If you are invested in the pregnancy, you want to anthropomorphize that pregnancy as soon as possible, and that’s a heartbeat for people,” Prager said.

Follow NBC HEALTH on Twitter & Facebook. 

Kaitlin Sullivan

Kaitlin Sullivan is a contributor for NBCNews.com who has worked with NBC News Investigations. She reports on health, science and the environment and is a graduate of the Craig Newmark Graduate School of Journalism at City University of New York.

When will heartbeat start in pregnancy?

What if there is no heartbeat at 6 weeks?

Can baby have no heartbeat at 8 weeks?