- This is it! At 3 weeks pregnant, this is the magic week. Conception has occurred.
Last week a single sperm fertilized your egg and you created a baby.
Congratulations! You now have a baby on board. Your pregnancy journey starts here.
It’s taken until now for the fertilized egg to travel to the uterus and begin to implant in the lining.
Here’s everything you need to know about pregnancy week 3 and your soon-to-be baby.
3 weeks pregnant
When you’re 3 weeks pregnant, it’s still very early days.
You’re probably not even aware of the amazing process of conception and your baby’s existence just yet.
You conceived only a few days ago and you haven’t had time to miss your next period.
Remember, the date of your last menstrual period will be used to calculate the official start date of your pregnancy and your due date – so keep this handy.
Can you tell you’re pregnant at 3 weeks?
At 3 weeks, you’re very unlikely to know you’re pregnant at this stage.
It’s too early to have missed your period. It’s most likely your next period won’t be due for at least another week, depending on your usual cycle.
Missing a period is normally the first clue you’ve conceived. Some women, though, have an intuitive feeling about their pregnancy. They feel like they ‘just know’ once they’ve conceived.
Some women start noticing breast tenderness or soreness. This is often one of the very early symptoms of pregnancy.
However, this is often confused with regular PMS symptoms you could be expecting anyway, which makes it hard to tell.
Many women don’t discover they’re pregnant until their missed period; by then they are already 4 weeks pregnant.
Positive pregnancy test at 3 weeks
Home pregnancy tests detect hCG (human chorionic gonadotropin) in your urine. This is what will take you from one little line, to two lines on a home pregnancy test.
The hormone hCG is produced by the developing placenta once the fertilized egg has been implanted in the uterine wall.
Raised hCG levels instruct your body to keep producing progesterone. This protects your pregnancy and stops your uterus from shedding its lining, which would produce your period. All this happens to make sure your developing baby stays where she’s supposed to.
Once your baby is developing and your pregnancy is in place, the altered hormonal balance also instructs your ovaries to stop releasing eggs for future menstrual periods. This prevents other sperm from fertilizing additional eggs while you’re pregnant. Could you even imagine…?
These days, home pregnancy tests are highly reliable. They have been designed to detect hCG earlier – even before your period is due.
Some are sensitive enough to pick up a positive result for the pregnancy hormone HCG one week after conception.
But at week 3, it might still be too early to turn your test positive. You’re unlikely to get a positive test at this stage.
hCG is produced only after the fertilized egg has travelled through the fallopian tube and is implanted into the uterine lining; this might not have happened yet.
Home tests can only detect hCG once the levels are high enough to be detected in your urine.
Read our article How Accurate is an Early Pregnancy Test for more information.
Does a positive pregnancy test at 3 weeks mean twins?
A positive pregnancy at 3 weeks could be an early indicator of twins but, equally, it might not be.
Not a great answer, I know, but there are many variables that can influence how early pregnancy can be detected.
When you are carrying twins (identical or fraternal twins) it’s true your hCG levels are generally higher. But in the really early days, levels are very similar to those in women who are carrying single embryos. It takes a little time for the hCG levels of twin embryos to overtake singleton levels.
Unfortunately, twin or multiple pregnancies can’t be confirmed simply by peeing on the stick. The only way to detect multiples definitively is by ultrasound.
Twins can normally be detected on a 6-week ultrasound. So if twins run in your family, or you think you might be carrying twins, you’ll just have to wait a little bit longer to know for sure.
3 weeks pregnant hCG levels
hCG levels can also be detected in your blood. This type of blood test is normally performed by healthcare providers in early pregnancy if it’s deemed necessary, based on your situation.
Repeat blood tests to measure hCG can be used to track the trend of your hCG levels, or if there are any concerns about miscarriage.
Serum (blood) hCG levels give a more accurate result. The blood results give a numerical figure, which can be tracked to see whether it’s going up or down.
hCG levels can be detected in the blood about 8-11 days after conception. Levels will then rise rapidly, peaking at the end of your first trimester. They then tail off throughout the rest of your pregnancy.
Standard hCG levels will vary drastically from woman to woman, and it depends a little on what your ‘normal’ is. As with many things in nature, everyone’s ‘normal’ is a little bit different. In other words, ‘normal’ levels can vary quite a lot.
Your ‘normal’ will depend on how many embryos you are carrying, and how your pregnancy is progressing.
A standard hCG level for 3 weeks is from 5-50mlU/mL.
Our article hCG Levels – What Should They Be Each Week? has more information.
Can I be 3 weeks pregnant and still get a negative test?
At this stage, it’s fairly likely you could be pregnant, and still get a negative result on your pregnancy test.
Week 3 is only technically the first week of your pregnancy.
If you take the test too early, the levels won’t be high enough yet to be detected, particularly on a urine test. But remember, this isn’t an indicator of the health or ‘strength’ of your pregnancy or baby.
That’s why it’s really important to take the test at the most appropriate time.
Read When To Take a Pregnancy Test to learn more.
3 weeks is usually too early to take a test if you want the most accurate result. Some women, however, will get a positive result by the end of this week.
Although you might be desperate to find out, if you think you could be pregnant it’s best to wait until next week. A few days at this stage can make all the difference to your hormone levels.
The best time to take a test is after the date your period would normally be due.
Can a miscarriage happen at 3 weeks?
It’s possible to have a miscarriage at any point after fertilization.
The majority of miscarriages (about 80%) will occur in the first trimester.
At 3 weeks, a pregnancy might end even before a woman is aware she’s pregnant. Most women don’t know they’re pregnant at this point.
At this stage, a miscarriage can easily be mistaken for a period.
The most common signs of an early miscarriage are:
- Vaginal bleeding/passing clots
- Cramping (period-type pains)
- Aching in the lower back
If you’re concerned about your symptoms, seek professional medical advice from your healthcare provider.
You can also read more in Signs Of Miscarriage | 5 Signs To Know.
3 weeks pregnant belly
At 3 weeks pregnant your belly won’t change at all, although you might feel a little bloated over the next few weeks.
Despite the magic happening inside, the outside world will be none the wiser for quite some time yet.
Your immune system is also suppressed so your body won’t reject your soon-to-be embryo as a foreign object.
Your ovaries produce progesterone for another 7 weeks or so; then, in your second trimester, the placenta will take over.
3 weeks pregnant – signs & symptoms
At this stage, pregnancy symptoms aren’t likely to have started yet.
Pregnancy hormones trigger early pregnancy symptoms, but the hormone levels aren’t yet high enough.
You might notice some signs over the coming weeks.
- Implantation bleeding. You might notice a very small amount of spotting or light bleeding that results from the fertilized egg burrowing into the uterus lining
- Pregnancy nausea. As hCG levels start to rise you might notice a feeling of queasiness. Morning sickness isn’t well named, as it can happen at any time of the day
- Tender breasts. Amazingly your breasts start to prepare for feeding your baby very early in pregnancy. This can cause them to feel sore, swollen and tender
- Vaginal discharge. Your body prepares itself to protect your baby by forming a mucus plug in the cervix. You might notice some discharge as this happens.
You might have none, some, or even all of these very early signs of pregnancy.
Every woman’s experience is different, but the two-week wait after conception can be a trying one.
3 weeks pregnant ultrasound
Unless your doctor has concerns about ectopic pregnancy it’s not common to have an ultrasound at 3 weeks pregnant.
Usually, one sperm fertilizes the egg in the fallopian tube; the egg then moves down into the uterus.
Sometimes, it doesn’t move and continues to grow in one of the fallopian tubes instead.
This is called an ectopic pregnancy, and it can be very serious and potentially life-threatening.
Ectopic pregnancies are very rare, occurring in about 1% of pregnancies.
Ectopic pregnancies aren’t usually discovered until a few weeks down the line.
My baby at 3 weeks pregnant
After it has been penetrated by the successful sperm, the egg begins to divide rapidly.
During its journey of around six or seven days, it continues to divide into a tiny ball of cells.
Over the next few days, it attaches itself to the uterine lining.
An estimated 50-60% of fertilized eggs never make it this far.
If the fertilized egg isn’t able to implant successfully into the wall of the uterus, the woman’s body will shed the egg along with the lining. This shedding causes the bleeding of a menstrual period.
However, once successfully implanted, your tiny embryo begins the work of growing in earnest.
A yolk sac starts to form; this provides the embryo’s first nutrients until the placenta takes over.
3 weeks pregnant baby size
At week 3 of pregnancy, your tiny embryo is a microscopic ball of cells.
Over the next nine months, your baby will grow from a collection of cells – smaller than a poppy seed – to the size of a pumpkin.