You might discover you are pregnant very early on.
The news a baby’s on the way can bring a lot of excitement, as well as worries and questions.
Sometimes an ultrasound is ordered to answer some of these questions.
An early ultrasound isn’t routinely performed or medically necessary. It can, however, be a helpful tool for gathering important health information about you and your baby.
The timing of an early ultrasound can make a big difference in what you can expect to see or discover.
Is a 7 week ultrasound too early to find out much useful information?
Read on to find out everything you need to know about a 7 week ultrasound.
7 week ultrasound
It’s not uncommon to be unsure about the date of conception, especially if you have irregular periods or if you became pregnant while on birth control.
In this case, an ultrasound functions as a dating scan to measure the size of the growing embryo and calculate the expected due date.
Spotting, past miscarriage, or fertility treatments are extra reasons why some women might wonder whether the baby is okay in there.
In these situations, an ultrasound can bring either reassurance, or confirmation of any concerns.
Reasons you might have an ultrasound at 7 weeks include:
- To determine gestational age of baby: An ultrasound can pinpoint the developmental age of the embryo based on crown-to-rump measurements
- To diagnose multiples: Especially following fertility treatments, it’s important to know how many babies might be growing. An early pregnancy scan takes a peek inside to find out whether there is more than one.
- To rule out ectopic pregnancy: Where the fertilised egg implants is vital to the success of the pregnancy. An early ultrasound can tell whether the pregnancy is developing in the uterus or outside, as it does in ectopic pregnancy
- To confirm heartbeat: If there’s any concern about the pregnancy, a scan at 7 weeks will determine whether everything is on track by detecting a heartbeat
- Vaginal bleeding: When there is concern about the amount or frequency of spotting or bleeding, an ultrasound looks at possible causes, such as ectopic pregnancy, hematoma, fibroids, or miscarriage.
How accurate is a 7 week ultrasound?
Many people wonder if it’s even possible to see a baby on a 7 week ultrasound, or how accurate dating is at this gestation.
Ultrasounds are most accurate in the first 12 weeks of pregnancy.
They look at your baby’s measurements, which are very predictable in the first 8-11 weeks.
An ultrasound up to 12 weeks should be able to predict your gestation accurately within 3-5 days.
7 weeks is definitely not too early to see your baby, but the image might be different from what you imagined.
We’ll go into detail later about what you can expect to see.
If you’re concerned about the safety of ultrasound, it’s reassuring to know studies have determined it to be a safe procedure.
Research is still inconclusive about the long-term effects of ultrasound for the baby.
What to expect at 7 week ultrasound
If you’re nervous or concerned about the results of your ultrasound, it’s a good idea to bring along a trusted friend or loved one to be with you – even if it just means there’s someone there to meet you after the appointment.
At 7 weeks pregnant, your uterus is still very low in your pelvis, so the ultrasound is usually done transvaginally.
Transvaginal ultrasound provides the best access to your uterus and the most accurate results in early pregnancy. You don’t usually need a full bladder for a transvaginal ultrasound.
You’ll be asked to undress from the waist down, and lie down on an examination table.
The sonographer will insert a narrow lubricated probe inside your vagina. You can ask to insert the transducer yourself, if you’re uncomfortable with another person doing it.
As in any internal exam, you might feel some pelvic pressure, which might increase or decrease as the probe is moved around to find the best angle for viewing the baby.
If your ultrasound is done transabdominally, some gel (usually quite cold) is placed on your belly, and the sonographer presses a transducer firmly on your low abdomen.
It’s moved around until it finds the best pictures of the inside of your uterus.
A partially full bladder is recommended for these ultrasounds as it helps to push your bowel out of the way so the uterus can be seen clearly.
The ultrasound itself doesn’t take very long, as there aren’t many parts to measure. It might take only a few minutes, or up to 30 minutes.
What can you see at 7 week ultrasound?
The first glimpse of your baby can be exciting.
At this stage of pregnancy you’ll want to know if the baby is growing at the right pace and if the tiny heart is beating.
Here’s what you can expect to see on the screen:
- Baby: The picture doesn’t resemble a baby very much just yet. Also known as the fetal pole, it can appear like a fuzzy white dot surrounded by a dark circle. Your baby will look a bit like a little blob, about the size of a blueberry. An embryo at 7 weeks is expected to have a crown-to-rump measurement of approximately 1 cm, or less than half an inch.
- Gestational sac: The dark circle surrounding the baby is the gestational sac. This first sign of early pregnancy can show up at 3-5 weeks. It’s a cavity of fluid that at 7 weeks will measure about 18-24 mm.
- Yolk sac: You might also be able to spot the yolk sac, which looks like a white ring or bubble near the baby. The yolk sac provides important nutrition and other functions for the developing embryo, and should measure 3-6 mm.
- Heartbeat: You might be lucky enough to see a heartbeat. It can be hard to see, depending on the position of the baby, but a small flashing or pulsing inside the form of the baby indicates a beating heart.
Can you see a heartbeat at 7 weeks?
Six or seven weeks gestation is just about the earliest a heartbeat can be detected via ultrasound.
A strong fetal heart rate (FHR) is a reassuring sign that the baby is developing well.
This will show up as a pulsing motion within the blob of the fetal pole. Expected range for a 7 week baby is 100-120 beats per minute (BPM).
At this stage a baby’s heartbeat can also be heard via Doppler.
Don’t stress too much if the baby’s heart cannot be found, though.
There are many reasons why the baby’s heartbeat might be hard to detect. Usually it’s because the dates are off or it’s just too early.
Other reasons why it might be more challenging to find the heart rate include: a tilted uterus; the baby is out of range; or the mother’s BMI.
Chances of miscarriage after seeing heartbeat at 7 weeks
In the earliest stages, new parents feel tentative about the pregnancy and worried about the chance of miscarriage (pregnancy loss before 20 weeks).
The sad truth is miscarriage occurs in at least 10-20% of known pregnancies.
The good news is that your likelihood of maintaining the pregnancy goes up if you’ve seen a heartbeat at 7 weeks.
According to this study, when you detect a heartbeat at 6 weeks, there’s a 78% chance the pregnancy will continue.
The chance of success goes up to 98% when you detect the heart at 8 weeks, and up to 99.4% chance after 10 weeks.
What if there’s a small baby or a weak heartbeat?
Sometimes a baby measures smaller than expected (5 mm or smaller) or a heartbeat is in the lower than normal range (under 100 BPM).
In these situations, it’s often possible the dates aren’t accurate.
Although it’s hard to wait, another appointment might be scheduled for a few weeks later to measure baby’s progress.
It’s also possible the baby isn’t developing normally. You might be told you have a high chance of miscarrying the pregnancy, and this is hard news to hear.
Measurements that are the biggest predictors of miscarriage include:
- Gestational sac 25 mm or greater with no fetal pole detected
- Fetal pole 7 mm with no heartbeat
- Yolk sac greater than 7 mm.
Because pregnancy loss is common, you probably know more people than you realise who have experienced it. It helps to talk with someone who can listen and understand.
For more information about what to look for if miscarriage is expected, including resources for coping with it, check out BellyBelly’s article Early Miscarriage – Signs, Symptoms, and What to Expect.
7 week ultrasound twins
Parents will be eager to know whether they need to prepare for more than one baby on the way.
An ultrasound at 7 weeks of pregnancy can certainly confirm the presence of twins or other multiples.
Twins can be diagnosed when ultrasound discovers more than one gestational sac or heartbeat.
It’s easiest to detect fraternal twins, as there are always two separate sacs.
Identical twins, when one embryo was formed and split into two, usually develop in the same gestational sac but have separate fetal poles and yolk sacs.
Can an ultrasound miss twins at 7 weeks?
Twins can be missed at 7 weeks or at any gestation.
It’s hard to believe but one gestational sac can hide behind another. One developing baby can be almost like a shadow of the other and difficult to detect.
Heartbeats can be so in sync that it is hard to distinguish one from the other.
Stories have been told about women who didn’t know they were having twins until a second baby was born. This is extremely rare, especially with the number of routine ultrasounds in today’s maternity care.
Most likely, if twins were not diagnosed at your 7 week ultrasound, you can expect no more than one bundle of joy.