Pregnancy 7th Week Ultrasound: What to Expect

Quick take: Your 7-week ultrasound is a significant milestone, often your first glimpse of your baby. During this scan, your provider will look for the gestational sac, yolk sac, fetal pole, and crucially, a flickering heartbeat. It helps confirm your pregnancy, estimate your due date, and check for early signs of a healthy developing pregnancy.

That flutter of nerves and excitement as you head to your first ultrasound appointment is incredibly common. At around seven weeks pregnant, this scan is often your very first opportunity to "see" your tiny baby and hear their heartbeat. It's a moment filled with anticipation, and it's completely normal to have a lot of questions about what you'll see, what's being measured, and what it all means for your pregnancy.

This early ultrasound is a powerful tool for your healthcare provider to confirm your pregnancy, assess its health, and accurately determine your due date. We understand that waiting for and going through this appointment can bring a mix of emotions, from pure joy to a touch of anxiety. Our goal is to walk you through exactly what to expect, so you feel prepared, informed, and reassured.

We'll cover everything from the tiny structures your provider will be looking for to what those measurements signify, and importantly, what to do if the findings aren't exactly what you hoped for. By the end, you'll have a clear understanding of your 7-week ultrasound and what comes next on your pregnancy journey.

What should I expect to see on my 7-week ultrasound?

At your 7-week ultrasound, your healthcare provider will be looking for several key structures that indicate a healthy, developing early pregnancy. While your baby is still incredibly tiny, about the size of a blueberry, the ultrasound can reveal a surprising amount of detail. The most common type of scan at this stage is a transvaginal ultrasound, which offers a clearer view due to the proximity of the probe to your uterus compared to an abdominal ultrasound.

Here’s a breakdown of what you can typically expect to see:

Gestational Sac

The first thing to appear on an early ultrasound is usually the gestational sac. This fluid-filled sac surrounds your developing embryo and is typically visible by 5 weeks of gestation. At 7 weeks, it should be clearly visible as a round or oval black area within your uterus. Its presence confirms an intrauterine pregnancy, meaning the embryo has implanted in the correct place, rather than an ectopic pregnancy.

The gestational sac grows approximately 1 mm per day in early pregnancy. Your provider will measure its size to ensure it's growing appropriately for your gestational age. An irregularly shaped or smaller-than-expected gestational sac might sometimes warrant further investigation, but often it's just a variation, and other signs like a strong heartbeat can be reassuring.

Yolk Sac

Inside the gestational sac, you should also see a smaller, round structure called the yolk sac. This is a vital structure in early pregnancy, as it provides nutrients to the developing embryo before the placenta is fully formed and takes over this role. It appears as a small, bright white ring within the gestational sac. The presence of a yolk sac confirms that the pregnancy is progressing beyond just an empty sac.

The yolk sac is typically visible around 5.5 to 6 weeks. At 7 weeks, it should be clearly identifiable. Its size and appearance are also indicators of a healthy pregnancy. For example, an abnormally large or small yolk sac can sometimes be associated with complications, though this is not always the case, and your provider will consider all findings together.

Fetal Pole

The fetal pole is the earliest visible sign of your embryo. It's a small, curved structure adjacent to the yolk sac, often described as looking like a tiny grain of rice. This is your baby! At 7 weeks, the fetal pole is still very small, usually measuring between 5 to 9 mm in length. From this tiny fetal pole, your baby's body will continue to develop rapidly.

Seeing the fetal pole is a significant milestone, as it indicates the presence of an embryo within the gestational sac. The measurements of the fetal pole are critical for accurately dating your pregnancy, which we'll discuss in more detail shortly.

Heartbeat (Fetal Heart Activity)

One of the most exciting and reassuring findings at a 7-week ultrasound is the detection of fetal heart activity, often referred to as a heartbeat. At this stage, it will appear as a rapid, flickering movement within the fetal pole. It might not sound like a distinct "thump-thump" yet, but the visual flicker on the screen is unmistakable.

A normal fetal heart rate at 7 weeks can range from 110 to 160 beats per minute (bpm), though it can sometimes be a bit slower or faster and still be considered healthy. The presence of a heartbeat is a strong indicator of a viable pregnancy and significantly reduces the risk of miscarriage moving forward. Many parents describe this moment as truly surreal and the first time their pregnancy felt "real."

Transvaginal vs. Abdominal Ultrasound at 7 Weeks

At 7 weeks, your baby is still very small and nestled deep within your pelvis. For this reason, a transvaginal ultrasound is almost always preferred for the clearest and most accurate images. During a transvaginal ultrasound, a small, lubricated probe is gently inserted into the vagina. While it might sound intimidating, it's typically not painful, though you might feel some pressure. It allows the ultrasound waves to reach your uterus directly, providing much better resolution than an abdominal scan at this early stage.

An abdominal ultrasound, where the probe is moved over your belly, might also be attempted, but it's less likely to provide clear images of such tiny structures at 7 weeks, especially if you have a retroverted uterus or a higher BMI. If an abdominal scan doesn't yield clear results, your provider will likely recommend a transvaginal ultrasound to get the necessary information. It's important to be prepared for the possibility of a transvaginal scan to avoid disappointment or having to reschedule.

What measurements are taken during a 7-week ultrasound?

Crown-Rump Length (CRL)

The Crown-Rump Length, or CRL, is the measurement from the top of your baby's head (crown) to the bottom of their buttocks (rump). At 7 weeks, this is the most accurate way to determine your baby's gestational age and, consequently, your estimated due date. This measurement is incredibly precise during the first trimester because embryos grow at a very consistent rate during these early weeks, before genetic and environmental factors start to cause individual variations.

At 7 weeks, a typical CRL measurement ranges from about 5 mm to 9 mm. Your provider will measure this tiny length, and the ultrasound machine's software will then calculate your gestational age and estimated due date based on this measurement. It's important to remember that a few millimeters difference can mean a few days difference in your due date, which is completely normal and doesn't usually indicate a problem.

The accuracy of CRL for dating is highest between 7 and 10 weeks of gestation. After 12 weeks, other measurements like head circumference and femur length become more reliable, but for this early stage, CRL is the gold standard.

Gestational Sac Diameter (GSD)

The Gestational Sac Diameter (GSD) is another important measurement. Your provider will measure the average diameter of the gestational sac. While less accurate for dating than the CRL once the fetal pole is visible, it helps to confirm that the sac is growing appropriately. At 7 weeks, a normal GSD typically falls within a range that corresponds to the gestational age.

Sometimes, if the fetal pole or heartbeat isn't yet visible (which can happen if your dates are slightly off), the GSD can give an initial estimate of gestational age. However, once the CRL is measured, it takes precedence for dating purposes. A significantly smaller-than-expected gestational sac for the observed CRL can sometimes be a soft marker for potential issues, but this would always be discussed with your provider in context of other findings and often requires follow-up.

Normal Measurement Ranges at 7 Weeks

To give you a general idea, here's what healthy measurements typically look like around 7 weeks:

These ranges are guidelines, and your provider will interpret your specific measurements in the context of your overall clinical picture. Don't worry if your numbers are slightly outside these ranges; a single measurement isn't usually cause for concern, but rather the overall trend and other signs of a healthy pregnancy.

Is it normal to not see a heartbeat at 7 weeks pregnant?

This is one of the most common and anxiety-inducing questions for expecting parents. The short answer is: sometimes, yes, it can be normal, but it always warrants careful follow-up. While a heartbeat is typically visible by 6 to 6.5 weeks with a transvaginal ultrasound, there are several reasons why it might not be seen at a 7-week scan, and not all of them indicate a problem.

Reasons for Not Seeing a Heartbeat

1. Incorrect Dating: The most common reason for not seeing a heartbeat at what you believe is 7 weeks is that your ovulation or conception happened later than you calculated. This means you might not be as far along as you think. If you are actually closer to 5.5 or 6 weeks, it's quite possible that a heartbeat hasn't developed enough to be visible yet. This is especially common if you have irregular periods or aren't sure of your last menstrual period (LMP) date.

2. Retroverted Uterus: Some women have a uterus that tilts backward (retroverted). This can sometimes make it more challenging to get clear images of the early pregnancy, even with a transvaginal ultrasound, potentially obscuring the fetal pole and heartbeat.

3. Early Development: Even with accurate dating, there can be slight variations in when the heartbeat becomes strong enough to be detected. Your baby might just be a slow starter, and within a few days, the heartbeat could become evident.

4. Equipment or Operator Variation: While less common in modern clinics, the quality of the ultrasound equipment or the experience of the sonographer can sometimes play a small role. However, most clinics are well-equipped and staff are highly trained.

5. Pregnancy Loss (Miscarriage): Unfortunately, in some cases, not seeing a heartbeat at 7 weeks can be a sign of a miscarriage or a non-viable pregnancy. This is a difficult reality, but it's important to remember that early miscarriages are common, affecting about 10-20% of known pregnancies, and are often due to chromosomal abnormalities that are beyond anyone's control. Your body's way of naturally ending a pregnancy that isn't developing correctly.

Next Steps if No Heartbeat is Seen

If your 7-week ultrasound doesn't show a heartbeat, your provider will almost certainly recommend a follow-up ultrasound. This is standard protocol to confirm the situation. Typically, this second scan will be scheduled 7 to 14 days after the first. This waiting period allows enough time for the embryo to grow and for a heartbeat to become visible if your dates were off or if development was a little slow.

During this waiting period, try to remain calm. It's a stressful time, but remember that a lack of heartbeat at 7 weeks doesn't automatically mean the worst. Many women go on to have healthy pregnancies after an initial scan without a heartbeat. Your provider may also check your hCG (human chorionic gonadotropin) levels with blood tests, as rising hCG levels can offer some reassurance while you wait for the next scan.

One BumpBites reader shared her experience: "I went in for my 7-week scan, so excited, but the doctor couldn't find a heartbeat. My heart sank. They told me to come back in 10 days. Those 10 days were the longest of my life, but at the follow-up, there it was—a tiny flicker! My dates were just a week off. It was such a relief." This story highlights the importance of the follow-up scan.

What if my 7-week ultrasound shows an empty gestational sac?

Discovering an empty gestational sac on your 7-week ultrasound can be incredibly disheartening and confusing. This situation is medically known as an "anembryonic pregnancy" or "blighted ovum." It means that a gestational sac developed and implanted in the uterus, but an embryo either never formed or stopped developing very early on and was reabsorbed, leaving an "empty" sac.

Understanding an Empty Gestational Sac (Blighted Ovum)

A blighted ovum is a common type of early miscarriage. It occurs when a fertilized egg implants in the uterus, and the gestational sac begins to grow, often producing pregnancy hormones (like hCG) that lead to positive pregnancy tests and early pregnancy symptoms. However, for various reasons, the embryo itself fails to develop or stops developing at a very early stage, before it's visible on an ultrasound.

On the ultrasound screen, you'll see a gestational sac, and sometimes a yolk sac, but no fetal pole or heartbeat where one would be expected for the size of the sac or the gestational age. This can be particularly confusing because your body still "thinks" it's pregnant, and you may continue to experience symptoms like morning sickness or breast tenderness.

Why Does an Empty Sac Occur?

The primary reason for a blighted ovum is typically a problem with the chromosomes in the fertilized egg. This is usually a random event and not due to anything you did or didn't do. Your body recognizes that the pregnancy isn't developing correctly and will eventually miscarry. It's a natural, albeit heartbreaking, way for the body to handle a non-viable pregnancy.

It's important to understand that a blighted ovum is not caused by stress, exercise, diet, or any other lifestyle factor. It's a biological issue that is beyond your control. It also does not necessarily mean you will have trouble conceiving or carrying a future pregnancy to term.

Next Steps and Emotional Support

If your 7-week ultrasound shows an empty gestational sac, your provider will usually recommend a follow-up ultrasound in 7-14 days to confirm the diagnosis. This is crucial because sometimes, if your dates are significantly off, the embryo might just be too small to be seen yet. However, if the gestational sac is large enough (e.g., typically >25 mm with no fetal pole, or a lack of growth over a week), the diagnosis of a blighted ovum becomes more certain.

If a blighted ovum is confirmed, your provider will discuss your options for managing the miscarriage:

• Expectant Management: Waiting for the miscarriage to happen naturally. This can take days or even weeks.
• Medical Management: Taking medication (like misoprostol) to help your body pass the pregnancy tissue.
• Surgical Management: A procedure called a Dilation and Curettage (D&C) to surgically remove the tissue.

This is a deeply personal decision, and your provider will help you choose the best option for your physical and emotional well-being. Going through an anembryonic pregnancy can be emotionally devastating. It's important to allow yourself to grieve and to seek support from your partner, friends, family, or a grief counselor. Many organizations offer support for pregnancy loss, and your healthcare team can provide resources. Remember, your feelings are valid, and you don't have to go through this alone.

How accurate is a 7-week ultrasound for determining due date?

The 7-week ultrasound is remarkably accurate for determining your estimated due date (EDD). In fact, it's considered one of the most reliable methods for dating a pregnancy, especially when compared to dating based solely on your last menstrual period (LMP).

The Precision of Early Dating

During the first trimester, particularly between 7 and 10 weeks, embryos grow at a very consistent and predictable rate. This consistency means that measuring the Crown-Rump Length (CRL) of your baby at this stage allows for a highly accurate estimation of gestational age. The American College of Obstetricians and Gynecologists (ACOG) states that an ultrasound in the first trimester is the most accurate method for establishing or confirming gestational age.

The accuracy of an early ultrasound for dating is typically within +/- 5 to 7 days. This means that if your ultrasound suggests you are 7 weeks and 2 days pregnant, your actual gestational age is very likely to be within a few days of that estimate. This precision is invaluable for several reasons:

• Confirming Gestational Age: It helps to confirm if your LMP-based due date is accurate or if it needs to be adjusted. This is particularly helpful for women with irregular cycles, those who conceived shortly after stopping contraception, or those unsure of their LMP.
• Monitoring Growth: Once your due date is established by early ultrasound, it provides a baseline for monitoring your baby's growth throughout the rest of the pregnancy. Significant deviations from this baseline later on can prompt further investigation.
• Timing Interventions: Accurate dating is critical for timing certain prenatal tests (like genetic screening) and for making informed decisions about interventions if your baby needs to be delivered early or if the pregnancy goes past term.

When Due Dates Change

It's quite common for your estimated due date to be adjusted after your 7-week ultrasound, especially if there's more than a 5-7 day discrepancy between your LMP-based date and the ultrasound-based date. For example, if your LMP suggests you are 7 weeks pregnant, but your CRL measurement indicates you are only 6 weeks and 3 days, your due date will likely be shifted forward by 4 days. This adjustment is made to ensure the most accurate dating for the remainder of your pregnancy.

Once an early ultrasound establishes a due date, it is generally considered the definitive due date and is usually not changed by later ultrasounds, even if subsequent measurements show slight variations. This is because, as the pregnancy progresses, individual growth patterns become more pronounced, making later ultrasounds less precise for dating purposes.

So, while it might feel a little strange to have your due date shifted, understand that it's a positive step towards ensuring the most accurate timeline for your pregnancy journey and all the care that follows.

What are the signs of a healthy pregnancy on a 7-week ultrasound?

When you have your 7-week ultrasound, your healthcare provider will be looking for a combination of visual findings and measurements that collectively indicate a healthy and viable early pregnancy. It's not just about one single sign, but how all the pieces fit together. Here are the key indicators of a healthy 7-week pregnancy on an ultrasound:

1. Clearly Visible Gestational Sac

A well-defined, round or oval gestational sac, appropriately sized for 7 weeks (typically 18-24 mm), is a positive sign. Its presence confirms an intrauterine pregnancy, and its regular shape suggests healthy development.

2. Clearly Visible Yolk Sac

Within the gestational sac, a distinct, round yolk sac (typically 3-6 mm) indicates that the embryo is receiving early nourishment and is progressing well. Its presence confirms further development beyond just the sac itself.

3. Visible Fetal Pole with Appropriate CRL

Seeing a clear fetal pole, the tiny embryo, measuring within the expected range for 7 weeks (5-9 mm CRL), is a strong indicator of healthy growth. This measurement is crucial for accurate dating and confirms the embryo's presence.

4. Presence of Fetal Heart Activity

This is arguably the most reassuring sign. A visible, rhythmic flicker within the fetal pole, corresponding to a heart rate between 110-160 beats per minute (bpm), is a very strong indicator of a viable pregnancy. Once a heartbeat is detected at this stage, the risk of miscarriage significantly decreases.

5. Appropriate Growth Since Previous Scans (if applicable)

If you've had an earlier scan, your provider will compare the current measurements to previous ones to ensure consistent growth. For instance, the gestational sac should grow about 1 mm per day, and the CRL should also show appropriate progression.

6. No Signs of Complications

Your provider will also be looking for the absence of concerning signs, such as:

• No signs of ectopic pregnancy: Confirming the pregnancy is in the uterus.
• No large subchorionic hematoma: While small blood collections are common, large ones can sometimes be a concern.
• No evidence of an empty gestational sac: As discussed earlier.

Essentially, a healthy 7-week ultrasound will show a gestational sac, a yolk sac, an embryo (fetal pole) of appropriate size, and a strong, regular heartbeat, all growing as expected within the uterus. Seeing these elements together provides immense reassurance and confirms that your pregnancy is off to a good start.

It's common to feel a wave of relief when you see these positive signs. Many parents describe feeling a deep connection to their baby for the first time at this appointment. One expectant parent told us, "Hearing that strong heartbeat, even just seeing the flicker, made everything so real. All the worries seemed to melt away for a moment."

How to prepare for your 7-week pregnancy ultrasound appointment?

Preparing for your 7-week ultrasound can help ease any nerves and ensure the appointment runs smoothly. While it's a quick procedure, a little preparation can make a big difference in your comfort and the clarity of the results. Here’s what we recommend:

1. Hydrate and Have a Full Bladder (Often, but check first!)

This is a common instruction for early pregnancy ultrasounds. A full bladder helps to push the uterus up and out of the pelvis, making it easier for the ultrasound waves to travel and providing a clearer view of your tiny baby. However, for a transvaginal ultrasound, which is common at 7 weeks, an empty bladder might sometimes be preferred for better comfort and image quality. **Always check with your clinic or provider beforehand** to confirm their specific instructions regarding bladder fullness. If they say full, aim to finish drinking about 24-32 ounces (around 1 liter) of water an hour before your appointment and try not to empty your bladder until after the scan.

2. Wear Comfortable Clothing

Choose loose, comfortable clothing, especially bottoms that are easy to adjust or remove. You'll likely need to expose your lower abdomen for an abdominal scan or remove your bottoms for a transvaginal scan. Elastic waistbands or a loose dress are good choices.

3. Prepare Your Questions

It's easy to forget what you wanted to ask once you're in the room. Write down any questions or concerns you have beforehand. This could include questions about your due date, what they're looking for, next steps, or any symptoms you're experiencing. Don't hesitate to ask; your provider is there to answer your questions.

4. Bring Your Partner or a Support Person

Many clinics allow a partner or a close support person to join you for this exciting appointment. Having someone with you can provide emotional support and share in the joy of seeing your baby for the first time. Check with your clinic's policy on visitors beforehand.

5. Understand the Procedure

Knowing whether to expect an abdominal or transvaginal ultrasound can help you mentally prepare. As discussed, a transvaginal ultrasound is often recommended at 7 weeks for the clearest images. While it can feel a little invasive, it's typically quick and not painful. Knowing this in advance can help reduce apprehension.

6. Don't Stress About Eating

Unlike some medical procedures, there are usually no dietary restrictions before a 7-week ultrasound. Eat normally unless your clinic gives you specific instructions. If you're experiencing morning sickness, make sure to eat something light that you can keep down.

7. Allow Extra Time

Appointments can sometimes run a little behind, or you might have paperwork to fill out. Plan to arrive a bit early and allow for extra time in your schedule so you don't feel rushed or stressed.

By taking these simple steps, you can ensure you're as comfortable and prepared as possible for this special milestone in your pregnancy journey.

From our medical team: "Your 7-week ultrasound is a foundational step in your prenatal care. It provides critical information for dating your pregnancy and assessing its early health. While it's normal to feel anxious, remember that the vast majority of early scans reveal reassuring signs. If there are any concerns, we will always guide you through the next steps with clear information and compassionate support, ensuring you understand every aspect of your care."

Myth vs. Fact

Let's clear up some common misconceptions about early pregnancy ultrasounds:

Myth: Ultrasounds are harmful to the baby.

Fact: Diagnostic ultrasounds, like the one you'll have at 7 weeks, use sound waves, not radiation, and have been used safely in pregnancy for decades. Leading health organizations like ACOG and the NHS confirm that there is no evidence that routine obstetric ultrasound is harmful to the fetus.

Myth: If you don't see a heartbeat at 7 weeks, it always means miscarriage.

Fact: While a concerning sign, it doesn't always mean the worst. The most common reason for not seeing a heartbeat at 7 weeks is incorrect dating—you might not be as far along as you think. A follow-up scan is almost always recommended to confirm. Many healthy pregnancies have an initial scan without a visible heartbeat.

Myth: Ultrasounds can determine the baby's sex this early.

Fact: At 7 weeks, your baby's sex organs are still developing and are far too tiny to be distinguished on an ultrasound. You typically won't be able to find out the baby's sex via ultrasound until around 18-22 weeks, during your anatomy scan.

Myth: An early ultrasound is painful.

Fact: While a transvaginal ultrasound (common at 7 weeks) can feel a bit unusual or cause some pressure, it should not be painful. If you experience pain, communicate it to your sonographer immediately. It's usually a quick and manageable procedure.

Key takeaways

• Your 7-week ultrasound is often your first visual confirmation of pregnancy and your baby's development.
• Key findings include the gestational sac, yolk sac, fetal pole, and crucially, fetal heart activity (heartbeat).
• The Crown-Rump Length (CRL) is the most accurate measurement at this stage for dating your pregnancy.
• If no heartbeat is seen, don't panic; incorrect dating is common. A follow-up scan in 7-14 days is standard.
• An empty gestational sac (blighted ovum) is an early miscarriage, often due to chromosomal issues, and requires careful management and emotional support.
• Prepare by checking bladder instructions, wearing comfortable clothes, and writing down your questions.
• This ultrasound is a significant step in confirming a healthy start to your pregnancy.

Frequently asked questions

What should I expect at 7 weeks pregnant ultrasound?

At your 7-week ultrasound, you can expect to see a gestational sac, a yolk sac, and a tiny fetal pole (your embryo) measuring about 5-9 mm. The most reassuring finding is usually a flickering fetal heartbeat, typically between 110-160 bpm. A transvaginal ultrasound is often used for the clearest view.

What is seen on a 7 week ultrasound?

On a 7-week ultrasound, your provider will look for the gestational sac (the fluid-filled home), the yolk sac (providing early nutrients), the fetal pole (the embryo itself), and evidence of a heartbeat within the fetal pole. These structures confirm an intrauterine pregnancy and its early development.

Is it normal to not see a heartbeat at 7 weeks?

Sometimes, yes, it can be normal, particularly if your ovulation occurred later than expected, meaning you're not as far along as you thought. While a heartbeat is usually visible by 6-6.5 weeks, a follow-up ultrasound in 7-14 days is standard practice to confirm dates and monitor development before any conclusions are drawn.

What if the ultrasound shows nothing at 7 weeks?

If the ultrasound shows "nothing" or an empty gestational sac at 7 weeks, it often indicates an anembryonic pregnancy (blighted ovum), where a sac develops but the embryo does not. However, if your dates are significantly off, the embryo might simply be too small to be seen. A repeat scan is always recommended for confirmation.

What is the size of a baby at 7 weeks on ultrasound?

At 7 weeks, your baby, or fetal pole, is very tiny, typically measuring about 5 to 9 millimeters (mm) in length from crown to rump. This is roughly the size of a blueberry. This measurement, known as the Crown-Rump Length (CRL), is crucial for accurately determining your gestational age and due date.

What are the signs of a healthy 7 week pregnancy?

Signs of a healthy 7-week pregnancy on ultrasound include a gestational sac of appropriate size, a visible yolk sac, a fetal pole with a CRL of 5-9 mm, and a strong, rhythmic heartbeat between 110-160 bpm. The absence of complications like an ectopic pregnancy or an empty sac also indicates health.

When to call your doctor

While this article offers general information, it's crucial to remember that it is not a substitute for personalized medical advice. Always contact your doctor or midwife if you have any concerns or experience any of the following:

• Heavy vaginal bleeding (more than a period, or with clots).
• Severe abdominal pain or cramping.
• Fever or chills.
• Any sudden, severe symptoms or feelings that something is wrong.
• If you have questions about your ultrasound results or feel overwhelmed by them.

Your healthcare provider is your best resource for individual guidance throughout your pregnancy.

References

1. American College of Obstetricians and Gynecologists (ACOG). (2017). Methods for Estimating the Due Date. Practice Bulletin No. 179.
2. National Health Service (NHS). (2022). Ultrasound scans in pregnancy.
3. Mayo Clinic. (2023). Fetal development: The first trimester.
4. Centers for Disease Control and Prevention (CDC). (2022). Miscarriage.
5. Royal College of Obstetricians and Gynaecologists (RCOG). (2016). Early miscarriage: Information for you.