Pregnancy is a continuum and there are no real divisions between each stage.
Pregnancy can seem to fly by or take forever to get through.
But let’s be honest! A lot happens from the moment of conception until a baby is born.
A human pregnancy lasts an average of 40 weeks – that’s 9 calendar months, 10 lunar months, or three-quarters of a year.
Some type of classification of stages, changes, and symptoms is most welcome when we’re trying to understand what happens throughout pregnancy.
There are different ways to discuss pregnancy stages. Many health care providers talk about pregnancy in terms of weeks, counting from your last menstrual period until birth.
If you’d like to see the stages of pregnancy, week by week, you can start at Week 1 with BellyBelly’s Pregnancy Week By Week series.
What are the 3 stages of pregnancy called?
There are many different ways of breaking down the stages of pregnancy; we’ve kept it quite simple when it comes to giving each stage a name.
The most common way to talk about pregnancy stages is to divide it into first trimester, second trimester, and third trimester.
This classification is so widely accepted, we’ve even developed another term – the fourth trimester – to refer to those very special first few months after childbirth.
Each of these stages is completely different and presents a unique set of challenges, as well as many magical moments.
Seeing how original obstetrics healthcare providers are at giving names, have a wild guess about what the three stages of labor are called.
Pregnancy trimester breakdown
Any length between 37 and 42 weeks is considered a full-term pregnancy. The average pregnancy is about 39 weeks or 40 completed weeks in length.
Health care providers have rounded the average length of pregnancy to 39 weeks and divided it into three:
- The first trimester starts from week 1 (the first day of your last menstrual cycle) and goes to the end of week 12, start of week 13
- The second trimester is from week 13 until the end of week 26
- The third trimester starts in week 27 and and continues until childbirth occurs.
Let’s see what happens in each of these stages.
What happens during the first trimester of pregnancy?
Week 1 – week 13
This is where it all begins. In fact, for the first two weeks of pregnancy, you’re not even pregnant. Pregnancy is said to start on the first day of your last menstrual period, although you won’t conceive until ovulation occurs between weeks 2 and 3.
In week one you’ll have your last period, like any other previous period. Then your uterus will start to get ready for conception.
Follicles begin to mature in your ovaries and ovulation will occur when an egg is released into the Fallopian tube. This is where the egg is fertilised by sperm; it then travels to the uterus where implantation occurs.
Most women discover they’re pregnant at some time around week 4-5, when they miss a period.
Although a home pregnancy test has confirmed the pregnancy, you might not really ‘feel pregnant’ or have any symptoms of pregnancy in the first month.
You won’t usually experience symptoms until week 6-8, when hormones start to rise, especially hCG and progesterone.
You might notice your breasts feel tender and swollen and you need to wee more frequently. You might also begin to experience mood swings, headaches and, of course, morning sickness.
You can read more in What Happens In The First Few Weeks Of Pregnancy?
The first trimester is a period of rapid development for your fetus, and you might feel exhausted as a result.
What happens during the second trimester of pregnancy?
Week 13 – week 28
The second trimester is often seen as the ‘best’ trimester of the three. You might feel a bit rough when you’ve made it to the end of the first trimester, but now you’re likely to start feeling much better.
For most women, nausea and morning sickness disappear around the 16th week of pregnancy, leaving them free to enjoy food again.
It’s common for women to have their first ultrasound scan towards the end of the first trimester.
You can read more in Nuchal Translucency Scan | 11 Common Questions.
As the second trimester commences, the risk of miscarriage reduces, meaning you might feel more relaxed about sharing your goods news. Some parents, though, choose not to wait to announce their pregnancy and have already told the world.
You’ll start to have a lot more energy again and exercise won’t be such a chore now. Swimming, yoga, and walking are all great exercises during pregnancy and will help you to stay fit for birth. If you can manage half an hour walk each day, this will be extremely beneficial for you, both emotionally and physically.
At around weeks 14-16, your baby bump could be making its grand debut; it will soon be time to invest in some maternity clothes.
You might be waiting for those first flutters, too. First-time mothers don’t usually feel this quickening until around 20 weeks.
These delicate flutters will only be noticeable to you at first, but soon your partner will be able to feel them too. Over the course of the second trimester, delicate flutterings will become definite kicks all over your belly, as your baby grows bigger and stronger.
Encourage your partner to start bonding with your baby by feeling the kicks, and talking to your bump each day. Your baby is already able to recognize your voice.
By the end of the second trimester, you might find stretch marks beginning to appear across your bump. Stretch marks are hereditary, and there’s not much you can do to avoid them, but moisturizing can reduce any discomfort.
Use natural moisturizers, such as organic extra virgin coconut oil, which has the added benefit of being free from chemicals and irritants.
You can read more in Pregnancy Stretch Marks-7 Facts.
Be sure to read 10 Ways You Know You’re In Your Second Trimester.
What happens during the third trimester of pregnancy?
Week 28 – week 40 (and beyond)
This is the home stretch and, for many, the hardest part of pregnancy. Although the nausea and fatigue of the first trimester are far behind you, you’re probably experiencing the aches and pains of late pregnancy.
The third trimester is also the one where everything feels more real as the big date gets closer. Your baby is growing bigger, and you might even be able to identify different body parts as you push on your abdomen. Your partner might feel more involved, too. Now, feeling baby from the outside is much easier and more rewarding.
During this final trimester, your baby is putting on weight and her lungs are still developing, ready for birth. You might find sleep elusive now, as you try to find comfortable positions and wake frequently for bathroom breaks.
Heartburn and indigestion are common complaints of this trimester. Try to avoid eating spicy foods, and stay upright immediately after eating to reduce symptoms.
Your growing uterus will reach up to your ribcage this trimester, and you might notice little feet sticking into your ribs throughout the day.
Your enlarged uterus could also be putting pressure on your already-squeezed-in-bladder, and you might spend half of your day walking to and from the toilet.
Your weight gain might slow during the last month of pregnancy, as your baby’s weight gain reduces slightly.
Light exercise, such as swimming, yoga, and walking, can do wonders for pregnancy aches and pains, so try to stay active.
It’s hard not to focus on the ‘due date’ but being aware that it is, in fact, a ‘guess’ date helps you to feel less impatient for baby to be born. It can help to give out a date later than your estimated one, to reduce any pressure you feel to have your baby.
During the third trimester, your baby is putting on the finishing touches for life outside the womb. Her lungs are still developing, which is why it’s important to wait for labor to start on its own. You might be amazed to know what causes labor to start: it’s your baby’s lungs signaling their readiness to breathe!
It can be a challenge to get through these final weeks of pregnancy but it’s worth it.
Be sure to read 10 Ways You Know You’re In Your Third Trimester to take your mind off your aching feet.
Which stage of pregnancy is the best?
I’m sure you’ll find women who will tell you which stage of pregnancy was their favorite, and why. This really depends on how you experience your pregnancy and your personal circumstances or previous experiences.
Some women have a very mild first trimester; some don’t even know they’re pregnant until their belly starts to show.
Some pregnant women refer to the third trimester as the best one for them, because they felt safer knowing their baby could already live independently outside of the womb. This is especially true for women who previously had difficult pregnancies, miscarriages, or premature babies.
When they look back, most women tend to agree that the second trimester of pregnancy was the easiest.
As the discomforts of the first trimester have fade away you start to feel human again. Your digestive system gets back on track and although your body changes are noticeable, the baby inside your uterus is growing and developing.
At the same time, the size and growth of your belly are still quite manageable, and you have a beautiful pregnancy glow.
Which stage of pregnancy is most difficult?
Once again this really depends on who answers the question.
It’s unlikely that many pregnant women would tell you the worst trimester is the second. You’ll find many who will say the first trimester is the worst. And probably just as many will give the medal to the third trimester.
The first trimester seems to be the hardest for many women. Especially for those who have had previous difficult pregnancies or a history of pregnancy loss. The anxiety these mothers experience during the first trimester starts to fade as their pregnancy progresses.
If first-trimester pregnancy symptoms are very severe this first stage might prove particularly hard, especially when it’s tempting to think these symptoms will never fade. In fact, it’s rare for them to persist for longer than the first few months.
Rarely, some women experience severe morning sickness – hyperemesis gravidarum – throughout their whole pregnancy.
The third trimester is the hardest for many women as the growth of their belly makes them feel heavy and clumsy.
Many suffer from pelvic girdle pain; others find breathing difficult or are unable to perform simple tasks without help.
Your breasts are fuller and might feel sensitive or even sore. You could feel some colostrum leakage at the least expected moments, and your movement could also be a bit restricted.
As you get closer to the birth date, your anxiety about giving birth might rise. Make sure you read plenty of beautiful, empowering, and joyous birth stories, to prepare your mind for a positive birth experience.
Here are some beautiful birth stories that BellyBelly members have shared with us.
Stages of pregnancy month by month
Long before the medicalization of birth, how did women keep track of their pregnancies?
Obviously, if they’d missed their expected period, that was a sign that they were possibly pregnant. But how did they know when their baby would be born?
It’s commonly believed women would count their cycles and pregnancies by lunar months. A lunar month was 28 days long, and there were 13 lunar months in one year (364 days plus one spare day). That means pregnancy was 10 months long.
The lunar calendar faded out of use, in favor of the Roman Solar calendar, which most western societies still follow. The months change in length: 28, 29, 30, or 31 days depending on which month it is. This means pregnancy doesn’t fit exactly into months, but more easily into weeks.
To find out how many months pregnancy is, you divide 40 weeks by 4 weeks and the answer is 10 months. But wait … pregnancy is 9 months long, isn’t it?
But the average number of weeks in one month is 4.4. Doing the math again, the answer is now 9 months. Phew!
Stages of pregnancy week by week
Counting pregnancy by weeks is also useful because babies tend to develop pretty much on a timeline over their gestation. It makes it easier for health care providers to know what to expect from your baby’s growth over time, and to pinpoint any problems early on.
This has meant there’s a much clearer way to get information for each pregnant woman.
Not only do you know that certain tests are offered at certain weeks but you can follow your baby’s progress and development in a much more concise way.
Being able to read something so specific about your baby’s growth is very fulfilling and rewarding.
If you’re following the BellyBelly Week By Week pregnancy updates, it’s great to know in detail what’s exactly going on each week.
The series has plenty of information – from knowing how big your baby is, to learning about more detailed development, like when hair begins to grow, when your baby develops eyelids and eyebrows, or little fingers and toes, and how early their sex organs develop.
You can also check out Pregnancy Symptoms Week By Week for an overview.
Pregnancy stages and symptoms
During the first few weeks of pregnancy, most of what your body is doing is making sure the newly fertilized egg implants safely into the uterus and begins the first stages of development.
Your body is no longer a priority for you alone. As your body protects and nurtures this new existence, it’s also affected by your baby’s development.
Your body might not seem to be enjoying this so much, though, with all the symptoms you might experience, such as:
Due to rising levels of certain hormones responsible for promoting pregnancy, many women experience some nausea and even vomiting. Commonly known as morning sickness, this can occur at any time of the day or night.
In the first few weeks, the embryo is nourished by the inner layer of the uterus, the endometrium. This is also where the connection between you and your baby will develop into the placenta.
During this time, nausea might put you off eating much but your body fat will increase, helping to sustain you and your baby. Usually, the sickness will resolve by the end of the first trimester.
Try reading Morning Sickness – 10 Best Morning Sickness Remedies for tips on how to get through.
Like nausea and vomiting, foods aversions are caused by changing hormones. They are also thought to act as a protective mechanism; it’s your body’s way of keeping you away from potentially harmful foods.
Even if foods cause your baby no harm, aversions might steer you towards eating foods with nutrients you and your baby require during the first trimester.
Sleep like a baby
Tiredness doesn’t even begin to describe the extreme fatigue women can feel in the first trimester. Although, from the outside, it doesn’t look like a lot is going on, your body is working incredibly hard and using a lot of energy to sustain your baby and pregnancy.
Often in the first trimester you’ll find yourself falling asleep at every other moment of your life, especially when it’s not convenient (mid morning siesta under the desk anyone?)
Your body is signalling you to rest. The more you rest, the more comfortable your body feels focusing on the development of your baby.
As pregnancy progresses and hormones settle, aversion and nausea are left behind. It’s quite common for women to experience food cravings in the second trimester, as their body lets them know what is needed.
Very often, the food you never paid too much attention to suddenly becomes your favorite ‘I need this right know’ food.
Sometimes weird pregnancy cravings happen, which could mean you’re experiencing a mineral deficiency. Always check in with your midwife or doctor if that happens, to make sure all is well.
Although food cravings are pretty normal, keep your health in mind, especially when you can substitute the nutrients you’re craving with a healthier choice.
Be sure to read Health Pregnancy Snacks – 25 Ideas for tips.
Increased sex drive
Hooray! It’s quite common for your sex drive to increase in the second stage of pregnancy. As your baby develops, your body is being flooded with oxytocin, the love hormone. There is also lots more blood flowing to your pelvis, sex organs, and breasts, increasing your arousal and sensitivity.
It’s perfectly natural and normal, so if you feel like having sex go for it! It’s very healthy for you, your baby, and your partner too.
You might want to take a peek at Pregnancy Sex Positions for tips on how to have satisfying sex during pregnancy.
Heaviness and lightening
Most symptoms that occur in the last trimester have to do with carrying a grown baby and getting ready for labor.
The baby takes up a large amount of space, so you feel heavier, which uses up a lot of energy and means physical movement is hard work. Your bladder is squished too, and your bowel movements might not be as frequent as before.
As the heaviness increases, your blood flow gets slower, causing fluid retention that might cause swelling in your feet.
At the end of the pregnancy, ‘lightening’ occurs when the baby descends into the pelvis. This will make it easier to breathe as this descent leaves more space for your lungs.
You might like to read Signs Of Labor | 7 Signs Your Baby Is On The Way.