Your First Trimester

computer.pngIf you've landed here, you probably just found out about your pregnancy and want to know what to expect. Or you're having yet another unfamiliar symptom and wondering, now what?? Either way, congrats and welcome to your first trimester! The good news is, you won't be in your first trimester for very long - at just 13 weeks long (and only really 10 weeks since you're not actually pregnant until around 3 weeks), it's the shortest trimester. The bad news is, the first trimester can be trying, which can make it feel longer than it really is. 

We want to make sure you have the most useful and helpful basic information about your first trimester in a quick and easy-to-read post. So, here goes.

How long is the first trimester?

13 weeks technically, but you're not technically pregnant until around 3 weeks, at the time of fertilization. The time you experience pregnancy symptoms is about 10 weeks, from weeks 3 to 13. 

What happens to baby in the first trimester?

Lots and lots and lots of growth and development. In fact, the most important parts of your baby's growth happen in the first trimester. Because of this, it's extra important during this time to be careful what you're exposed to in the environment, and in what you eat and drink, including medication. At the end of this trimester, your baby will grow from a clump of cells to a fully formed baby with all major systems, organs, limbs, and even fingernails, and measures around 3 inches and weighs .5-1 ounce! 

What happens to me in the first trimester?

Oh boy, where do I start?! From the outside, most people wouldn't notice a thing. From your point of view, you'll likely experience lots of changes and symptoms. The following is a list of possibilities -- your experience can vary widely from the next person's, so don't fret if you don't have a specific symptom (be thankful!).

  • Missed period (of course!)
  • Cramping (similar to period cramps)
  • Tender breasts and breast fullness (similar to what you experience before your period)
  • Fatigue, with a capital F and three exclamation points 
  • Nausea, sometimes accompanied by vomiting
  • Dizziness, lightheadedness, or faint
  • Frequent urinating
  • Heightened sense of smell and taste, along with aversions to food and scents
  • Heartburn
  • Constipation
  • Headaches
  • Mood and emotion fluctuations, including irritable, sad or "weepy," anxious, stressed, as well as exhilarated

Will I start to "show" in the first trimester?

If this is your first pregnancy, probably not. If this is a subsequent pregnancy, maybe -- but probably not. When most people use the word "show," they want to know if other people will be able to notice their pregnancy. And generally, unless it's a very close friend or family member, others won't know. On the other hand, you will most likely notice changes in your waistline very early on, whether it's visual changes like a bloated tummy, or physical changes like difficulties fastening your jeans.  

Will I be able to feel kicks in the first trimester?

99.9% of the time, no. There are always outliers, of course, but generally speaking, you won't feel baby kicks until the second trimester, around 15-20 weeks. 

What happens during prenatal care in the first trimester?

You'll go to your first prenatal appointment during which your care provider will "confirm" your pregnancy via urine analysis, blood test, and/or transvaginal ultrasound. Your first appointment is generally around the 8 weeks mark. Your doctor or midwife also will perform a general baseline health work up at the appointment, which may include blood/lab work, weight check, blood pressure, medical history information, a pap smear, and information on healthy pregnancy practices. It's never too early to start asking about your birth, so don't hesitate! The earlier you know about your care provider's birth practices, the better, as how you're cared for during labor and birth can affect you and your baby for the rest of your lives. Check out our tips post, "First Trimester: Choosing Your Doctor or Midwife" to learn more about how to choose a good care provider. 

What symptoms should I worry about in the first trimester?

The first trimester carries the highest risk of miscarriage. Signs of a miscarriage include consistent/continuous low back pain that is mild to severe; continuous or intermittent cramping (indicating contractions); vaginal bleeding with or without cramps, brown to red in color; blood tinged mucous (pink or red); passing tissue and/or clots. 

Other signs that could indicate a complication and require medical attention include:

  • Severe abdominal pain
  • Fever and/or chills
  • Painful urination
  • Excessive thirst
  • Swelling or puffiness in hands and/or face
  • Vision changes
  • Excessive nausea and vomiting 
  • Severe headache
  • Leg or calf pain and/or swelling in one leg

Other resources for your first trimester

We've written lots of other fantastic resources on the first trimester to help answer the many questions that pop up during this time. Check it out:

Making the Most of Your First Prenatal Appointment

How You'll Feel During Your First Trimester

5 Things You Should Know in Your First Trimester

First Trimester: Choosing Your Doctor or Midwife

10 Ways to Survive and Thrive in Your First Trimester

Bleeding in the First Trimester - What Does it Mean?

Am I Still Pregnant? First Trimester Concerns

First Trimester: Symptoms & Solutions

Changes in Your First Trimester of Pregnancy

First Trimester Checklist

Top Nutrients You Need in Pregnancy by Trimester


What do you remember about your first trimester? What helped? What would you do differently next time?

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