Here you can find a detailed week by week guide to what you can expect during your pregnancy. For example, do you know what a nuchal translucency screening test is, or when you should get one? Or are you wondering when you’ll be able to first feel your baby kick? You’ll learn about how your own body develops during your pregnancy, as well as your baby’s. I’ve also included common symptoms you’re likely to experience, and tips to deal with them. Most women deliver their baby between weeks 37 and 40, but on the rare occasion your baby can be born early or late. Don’t worry! Find your week in the below pregnancy calendar, and be sure to comment if you have any questions or suggestions!
First Trimester of Pregnancy
Weeks 1 and 2
Did you know during your first week of pregnancy as measured by doctors, you’re not even pregnant? It might sound counterintuitive (okay, downright contradictory), but there’s a good biological reason that week 1 of the 40 week cycle falls before conception even occurs.
Week 3
This is it! This is the big week you actually conceive. Your pregnancy is calculated to have started on the first day of your last menstrual period (LMP).
Week 4
At this point your baby is still a microscopic ball of cells (next week it’ll stop looking like a ball) which wouldn’t even show up on an ultrasound. There’s a lot going on in that little bundle though.
Week 5
The embryo which is going to become your baby is no longer microscopic by this point, but it’s still no larger than a sesame seed. The two main systems which are starting to form by this point are the nervous system and the circulatory system.
Week 6
By this point your baby is no longer the size of a sesame seed—it now measures half an inch long. The spine is nearly fully developed and lungs have appeared and branches have started to form within.
Week 7
The biggest thing going on during Week 7 is the development of your baby’s brain. Each minute your baby’s brain is adding 100,000 nerve cells! The very first pathways in the central nervous system are starting to form.
Week 8
Your baby is still only about the size of a raspberry, but expanding fast. Your baby is also starting to look a lot more human; the vestigial tail is almost gone by now and the face is becoming more defined.
Week 9
Welcome to the last month of your first trimester! By now you’ve survived morning sickness, dizziness, mood swings, and more as your baby has transitioned from a tiny ball of cells called a blastocyst into something starting to resemble a brand new human being.
Week 10
As your placenta develops, so does your baby, now two inches in length and more human-looking by the day. Last week your baby started building little muscles; this week your baby will start building little bones!
Week 11
If you baby is a boy, last week he was already producing testosterone from his primitive testes. If your baby is a girl, this is the week her ovaries will start to develop.
Week 12
You’re nearing the end of your first trimester, and your baby now weighs half an ounce and is the size of a plum! What’s happening inside your baby’s growing body this week?
Week 13
Now that you’ve reached the bridge between your first and second trimesters, there’s some good news, which is that your body is finally starting to adjust to being pregnant.
Second Trimester of Pregnancy
Week 14
Congrats—you made it to your second trimester! Now it’s official—you’re a third of the way through your pregnancy and over that first rough phase.
Week 15
During Week 15, your baby starts looking less like a space alien and more like a baby. For one thing, his or her ears are now located on the sides of the head, while his or her eyes are finally in the front of the head.
Week 16
Your baby is now four to five inches long! The most exciting development this week is that those sensory organs are finally forming to the point where they are actually starting to function as senses.
Week 17
This week your baby is discovering how to suck and swallow. These movements will be some of the first he or she will use after being born to drink milk from a bottle or breastfeed.
Week 18
Your baby is now about the size of a grapefruit and weighs about five or six ounces. His or her senses are continuing to develop and clarify, and he or she can now probably hear your voice more clearly.
Week 19
This week your baby develops a protective fatty coating. You may very well feel him or her kicking now while you kick furiously as a result of your leg cramps.
Week 20
During week 20 of your pregnancy you’ll be able to get an answer to one of the biggest questions about your baby—whether he or she is a he or a she!
Week 21
Previously, your baby received nutrition solely through your placenta. While the placenta still plays an important role, your baby is now using his or her mouth to take in nutrition as well!
Week 22
This week your baby weighs a whole pound! He or she is about the size of a small baby doll. As your baby’s senses develop, he or she is probably starting to experiment with them a bit.
Week 23
During your 23rd week, your baby is still about the size of a small baby doll, but he or she is beginning to fill out that saggy skin with brand new baby fat. This is the month your baby’s skin will finally stop looking translucent.
Week 24
Your baby’s face is very well formed and the eyes, while still closed, are fully developed, along with eyelashes and eyebrows. Your baby is even starting to experience rapid eye movements (REM), the movements associated with dreaming.
Week 25
Your baby now weighs more than a pound and a half and is developing surfactant in his or her lungs. What is surfactant? This is a substance which helps keep the alveoli of the lungs open and helps them to expand.
Week 26
Week 26 is the week that your baby’s eyelids, which until now were fused, start to open up. There isn’t a whole lot to look at, but that’s all right since your baby’s brain is still developing.
Week 27
Congratulations! You’ve reached the end of your second trimester! While your baby is curled up to fit inside your womb (thank goodness), he or she still measures about 15 inches from head to toe!
Third Trimester of Pregnancy
Week 28
Congratulations—you’ve just passed another huge milestone in your journey. Your baby now weighs around two and a half pounds! He or she probably measures about 16 inches from head to toe.
Week 29
It’s the second week of your last trimester and your baby is almost three pounds and growing faster than ever. You’re probably doing the same about now, resulting in unsightly varicose veins and stretch marks.
Week 30
During Week 30 of your pregnancy, your baby’s brain is learning how to do all sorts of new things, and many of those things are unconscious, like regulating your baby’s body temperature.
Week 31
Your baby has grown perhaps another inch in the past week, but he or she won’t be getting much longer from head to toe before you deliver. Your baby’s still getting heavier, though, as baby fat comes in.
Week 32
What’s your baby getting up to this week? Much of the physical development is complete by this time, though fat is still coming in and your baby is becoming less translucent.
Week 33
Your baby’s immune system is under development this week. Your antibodies are still playing an important part in your baby’s defense, but now your baby has an immune system in place, and soon your antibodies won’t be necessary anymore.
Week 34
This week your baby probably weighs about five pounds, and is still gaining weight at the rate of about a half a pound a week! That means that your baby will pack on several more pounds before the big day.
Week 35
This week you’re probably feeling stronger Braxton Hicks contractions (or experiencing them more frequently). Another thing you’ll be feeling more frequently is the need to urinate.
Week 36
Your baby’s immune system, which has been developing over the past several weeks, is now in good enough shape that your baby can survive outside the womb without your antibodies for protection.
Week 37
By now your baby weighs 6 or 7 pounds and is considered “full term,” though 37 weeks is still a bit early for a birth in most cases—38 to 42 weeks is considered normal and healthy.
Week 38
Your baby is probably around seven pounds right now. For the most part your baby is physically developed, though finishing touches are still being put on the lungs and digestive system.
Week 39
Your baby weighs about 7 or 8 pounds and is basically done growing for the time being—at least on the outside. Inside your baby’s soft skull, brain tissue continues to grow and new connections are made every day.
Week 40
This is it—this is the last week of your pregnancy—or not. Only about 5% of women are estimated to actually deliver by their due date. Normal deliveries can happen anywhere between weeks 38 and 42.
Week 41
Your baby may not feel as active these days; this isn’t really because your baby’s inactive—it’s because your baby doesn’t have that much room so that activity has become confined.
Week 42
Your baby is about 7 or 8 pounds now and measures approximately 19-22 inches from head to toe. If you don’t feel him or her moving around that much, it’s because there isn’t enough room left in your womb for a lot of movements.
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