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First Trimester - Week By Week

Your First Trimester (Weeks 1 – 13)

woman in early pregnancy holding a yoga poseCongratulations on your pregnancy! There's so much to discover of the next months as your body changes and your baby grows.Your first trimester is the first 13 weeks of pregnancy. Below is week-by-week overview of your first trimester and baby’s development.

Week 1

You’re not actually pregnant yet. Ovulation and conception are hard to determine, so doctors use your menstruation cycle to determine conception. Doctors won’t consider you pregnant until the first day of your last period. So you could actually be a couple weeks in depending on your cycle.

What to do: You should start taking prenatal vitamins and schedule your first prenatal appointment where they can determine just how far along you are. Make sure to quit any unhealthy habits such as drinking and smoking and eat healthy and continue to exercise.

Week 2

Again, depending on your cycle, you may not yet be pregnant or you may be 2-3 weeks pregnant, but follow the same guidelines as in week 1. Some early signs of pregnancy can include breast tenderness or soreness, fatigue, spotting, bloating, and morning sickness.

Week 3

You may or may not be pregnant. Again, your doctor won’t say one way or the other until you’ve missed your period or gone in for a test to confirm. If you are pregnant, you’re probably not yet experiencing many symptoms as your pregnancy hormones are just starting to kick in. Make sure to check any prescription or over-the-counter medications you may be taking and if you haven’t done so yet, schedule your first prenatal appointment.

Week 4

Congratulations! You’ve missed your period and have now confirmed you’re pregnant through an at-home test or scheduled appointment. Most women at this point still may not realize they are pregnant unless actively trying and waiting for this moment. No worries. At this point, it’s important to get that prenatal check-up scheduled and a firm confirmation of pregnancy. If you haven’t started those vitamins or quit those bad habits, now’s the time!

Baby is about the size of a poppy seed.

Week 5

This is the week most women find out they are pregnant. Not only because of a missed period, but also because pregnancy hormones start to kick in providing those other tell tale signs, including sore breasts, nausea, fatigue, and morning sickness. This isn’t to say you will or will not have these. Every woman and pregnancy is different.

Can you believe your baby is already starting to form major organs! While only the size of a grain of sand, in the next week, you’re baby will double in size. Make sure you’re providing essential nutrients for you and baby, including a prenatal vitamin, lots of water, and healthy food choices.

Baby is about the size of a sesame seed.

Week 6

Baby has now doubled in size and it about .25 inches long. Growing a baby is an emotional ride. Add in those pregnancy hormones and you might be wondering why you’re suddenly nervous or anxious or scared. Don’t worry. These are all normal feelings as you adjust to the idea that you’re going to be a mom! Along with mood swings, you may also continue to have sore breasts, fatigue, morning sickness or nausea, and cramping or spotting.

As for baby, they are busy working on growing those cute little features like their nose, chin, ears and cheeks.

Baby is about the size of a sweet pea.

Week 7

Baby has again doubled in size and is now about half an inch long – or about the size of a blueberry. Previous symptoms could still be in full throttle or maybe you’ve noticed some new symptoms, such as aversions or cravings of certain foods, acne, or bloating. These are all common symptoms that you may or may not get.

Big brain growth is happening in baby, along with the heart. If you haven’t done so already, schedule your prenatal check-up. For low-risk pregnancies it’s common for your first prenatal to occur between 8 – 10 weeks pregnant. Make sure you’re also taking a prenatal vitamin, eating well, and getting in some healthy exercise.

Baby is about the size of a blueberry.

Week 8

If you have your first prenatal check-up scheduled, you may get to hear baby’s heartbeat for the first time during an ultrasound! This ultrasound can also help tell how far along you are more accurately.

As far as symptoms go, you may be noticing your sense of smell is a little more heightened. This is normal, but may not be lovely if you also have nausea. What’s also normal? Odd dreams. Don’t fret over them, but you may want to jot them down to look back at since they can get a little weird. Remember, there’s a lot happening at once!

Why are you so tired all the time? Well, you’re growing a baby . . . and because of this, your blood sugar and blood pressure may be lower as you’re also producing blood cells for your baby. It’s normal and a nap be much needed to re-energize you. Take advantage of it now!

Baby is about the size of a kidney bean.

Week 9

The good and the bad – this is the week that your symptoms will most likely be their worst at your hormones are at their peak level. Hopefully it’s smoother sailing after this week if you have had severe symptoms.

You might also feel like you need to urinate a lot more now. At the uterus grows, it begins to start putting pressure on your pelvic area so you may feel the need to go more often. Don’t let this deter you from staying hydrated and drinking lots of water!

You may also be reaching for tissues more often as you’re producing more mucus; another normal symptom of pregnancy.

Every woman shows at different times, but many start to feel it’s a little harder to get into those pants at this point. There is a lot of helpful tools to extend the wear of your everyday clothes or consider going shopping for some comfy maternity clothes!

Baby is about the size of a grape.

Week 10

This is the week most women begin to show. Because of the growth of both your baby and your uterus to make more room for them, you may experience round ligament pain as your uterus begins to stretch. Aches and pains around your abdomen at this point are common, but if it’s severe, contact your provider.

Whether you decide to breastfeed or not, your breasts are preparing to nourish your little one, so you’re probably noticing them growing as well. Invest in some comfortable and supportive bras to help alleviate back pain.


Baby is developing quickly. They have fully developed vital organs which are beginning to function and they are now measuring over an inch long! 

Sometime between weeks 10 and 14 you will schedule a Nuchal Translucency Measurement ultrasound, which measures the fluid in the back of the fetal neck and is used to screen for chromosomal abnormalities like Down syndrome.

Baby is about the size of a strawberry.

Week 11

You’re getting close to your second trimester! Have you noticed you may be forgetting common things? Pregnancy brain is completely normal as hormones and your body is changing. You may still be fatigued, have mood swings, and nausea, but you may now also have more gas, leg cramps and may start to see the linea nigra, a dark line that runs down the center of your belly. Don’t worry, this isn’t a permanent line, but may take a little time after birth to disappear as it is caused by breastfeeding hormones.

Wondering when to announce your pregnancy? Many women tend to wait until the beginning of the second trimester, but as long as you’ve heard and seen your baby’s heartbeat, the risks of miscarriage decreases dramatically (to around 3%). At this point, it is really your preference on who and when you announce your exciting news!

Baby is about the size of a fig.

Week 12

Your baby is now over 2 inches long and has developed all organs. Now they just need to continue to grow and nourish those organs. At this stage, baby’s can now curl toes and open and close fingers.

Your first trimester is usually the most intense in regards to symptoms, but hopefully they should be waning soon. What you may notice around this point is dizziness and headaches. While completely normal, it’s important to make sure you’re getting enough rest, water, and decreasing stress. Make sure to eat regularly as blood sugar can drop quickly while supporting another human being growing in your belly!

Baby is about the size of a lime.

Week 13

You are now technically three months pregnant and one-third of the way through your pregnancy! Congratulations.

You’re probably starting to feel a lot better if you had a lot of the symptoms we’ve mentioned. Energy will start to increase, including your sex drive. You may also see more visible veins. You need to supply a lot of blood to your baby for their development so this occurs with the increased blood flow.

Now that you have all this energy, it’s a good time to consider planning a babymoon. A babymoon is a great time to travel with your significant other to prepare and relax before you’re up all hours of the night with your precious little one. It’s time for a little R & R.

Make sure you’re still eating well and getting in some moderate exercise. Ask your provider about healthy weight gain for you and baby.

Baby is about the size of a lemon.

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