Pregnancy Week 3: Read all about the 3rd week of pregnancy from symptoms to baby size and from the increase in size of your belly to the required tests and ultrasounds!
Congratulations! At 3 weeks pregnant, things start to
really pick up.
Either at the end of 2 weeks pregnant or the beginning of 3
weeks pregnant, your body should have ovulated, and your baby was officially
Conception happens at the moment that the egg is
fertilized by a sperm! Once the first sperm reaches and penetrates the egg, a
layer immediately forms on the outside of the egg to prevent any more sperm
from getting in. The sperm joins with the egg to create your baby! Of course,
at this point, your baby is officially referred to as a zygote.
At this early stage of pregnancy, you may not
experience any symptoms at all. However, now that your baby has actually been
conceived, there is a chance for you to start experiencing the beginning of
real pregnancy symptoms!
As soon as the egg has been fertilised, your body will
begin producing increased levels of oestrogen and progesterone. These are
pregnancy hormones that will prevent the lining of the uterus from shedding
like it typically would when you get your period. These hormones are what supports
your baby in the very beginning before the placenta is developed enough to take
over and produce the pregnancy hormone known as human Chorionic Gonadotropin or
One symptom that you are more likely to experience at
3 weeks pregnant would be implantation bleeding. Some women experience this
while others do not. Some women shed a small amount of blood when the egg
implants into the uterus several days after fertilization. This is likely to
occur at the end of 3 weeks pregnant or possibly the beginning of 4 weeks
pregnant. Even if you don’t experience this symptom, there is a possibility
that you simply missed it since it is usually such a small amount.
One of the earliest signs of pregnancy is frequent
urination. Get ready, though, because this tends to be a mostly universal
pregnancy symptom that lasts the whole 9 months. You may not experience it
quite yet at 3 weeks pregnant, but it is more than likely coming at some point
and will only get worse when your baby and uterus start growing more and
putting pressure on your bladder.
Your breasts are another thing that is likely to
change early on. It isn’t too unusual for changes in your breasts to be your
first official sign of pregnancy. Some women experience this early on, even at
3 weeks pregnant, while some experience it later on at different points in
pregnancy. Sore and sensitive breasts are a sign that your body is slowly
preparing to produce breastmilk to nourish your baby after birth. You may also
notice an increase in breast size, nipple size, and changes in nipple and
Another symptom that is quite common from early on in
pregnancy is fatigue. Your body works hard at creating a new little person,
even from the very beginning. So, it makes sense that you tend to get tired
easy and have less energy. This is another symptom that you may or may not
experience at 3 weeks pregnant. If you aren’t experiencing fatigue yet, you
likely will in the coming weeks. Many expecting mums spend most of the first
trimester completely exhausted.
Sense of Smell
Something else that many pregnant women experience as
one of their very first pregnancy symptoms is a heightened sense of smell. This
wouldn’t be unusual to experience at 3 weeks pregnant because of higher levels
of oestrogen and progesterone. You might suddenly notice that you can smell
everything and may even be much more sensitive to some smells. This can also
lead to food aversions, which are not unusual during pregnancy.
This is the one you’ve been waiting for. Nausea is one
of the most well-known pregnancy symptoms and is often referred to as morning sickness. It’s called morning sickness because it’s likely to occur when you
first wake up due to an empty stomach, but it can definitely occur at any point
during the day or night. It can begin from very early on such as at 3 weeks
pregnant, but for most expecting mums, it begins at around 5 weeks pregnant.
Pregnant Baby Size
Now that conception has occurred, there is actually a
baby to discuss the size of! Of course, at this point, the baby – currently
referred to as a blastocyst – consists of a tiny group of cells. Remember that
the egg cell alone is large enough to be seen by the naked eye. Your baby is
currently about the size of the head of a pen. He or she currently measures at
just under 0.05mm.
3 Weeks Pregnant
There is definitely more excitement this week in the
way of baby development! That’s because there is officially a baby developing
at 3 weeks pregnant! At this point, your egg has been fertilized. A fertilised
egg is referred to as a zygote. As soon as fertilisation occurs, the zygote
begins to split and multiply into many cells bunched together. It undergoes
this process of multiplying as it travels through the fallopian tube into the
The time the zygote takes to get to the uterus can be
up to around 6 days, so by the end of 3 weeks pregnant, or possibly the start
of 4 weeks pregnant, your baby consists of hundreds of cells and is referred to
as a blastocyst. The blastocyst implants itself into the uterine wall where it
continues to grow and develop.
At this early stage of your pregnancy, every aspect of
your child’s DNA is already determined! So, even though it will be quite a
while before you find out – your baby’s gender, eye colour, hair colour, and so
much more are already determined and written in the DNA of that tiny
blastocyst. Certain cells within the blastocyst have already separated into
groups. One layer of the cells will become your baby – the embryo. Another will
become the amniotic sac, and another will be the placenta!
Pregnant Belly Size
Lots of things will be happening inside now, but at 3
weeks pregnant, there still won’t be any signs of your belly actually looking
pregnant on the outside. It will still be a good while before your uterus has
grown enough for you to start showing. Rest assured, it is already starting to
You won’t likely have any tests quite yet at 3 weeks
pregnant. However, some of the most sensitive early detection pregnancy tests may be able to show you a positive
result by the end of this week. It is still early, though. So, if you do decide
to go ahead and take an at-home pregnancy test, know that it may be negative
simply because you’ve tested too early.
See, pregnancy tests are testing for the pregnancy hormone
hCG. You won’t actually start producing this hormone until after the blastocyst
implants into the uterus. The earliest you can expect that to happen would be
near the end of 3 weeks pregnant. The best time to test for pregnancy and make
sure you don’t accidentally get a false negative would be closer to 4 to 5
weeks pregnant, after you have already missed your period.
Since you probably won’t know for sure that you are
pregnant at 3 weeks pregnant, you probably won’t see your doctor yet. So, you
shouldn’t expect a 3 weeks pregnant ultrasound. However, if you did have an
ultrasound, you really wouldn’t be able to see the baby yet anyways.
The blastocyst destined to become your sweet bub is
still too small to be seen on the ultrasound. One thing you could see if you
did have a 3 weeks pregnant ultrasound, though, is how thick the lining of your
uterus is. This would definitely signal that your little blastocyst is in there
even if it can’t be seen yet!
Now that you are officially pregnant, nutrition is
more important than ever! You need to make sure that your body is as healthy as
possible to help support your pregnancy. It can be difficult to get everything
you need each day through diet alone, so while eating healthy is vital, you’ll
also want to supplement with a good prenatal vitamin. Tons of important
development is going to be happening over these first few weeks after
Welcome to Babyinfo – the ultimate pregnancy and newborn information guide. We are here to help you find all the pregnancy and baby info you need to make the most beautiful experience of your life even better.
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