First Trimester of Pregnancy

During the first trimester of pregnancy, your body goes through a ton of changes. We’re serving up articles and videos packed with information and advice to help you navigate your first trimester.
ByThe Bump Editors|Updated November 10, 2023
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pregnant woman sitting on the bed
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Key Highlights for the First Trimester

The first trimester is an emotional rollercoaster filled with moments of joy, anxiety, excitement and dread. And the physical changes are just as dramatic. Your body is working overtime to grow new life, and major things are happening on a cellular level every single day. (By the end of your first trimester, several of baby’s major organs will have started to form, and you’ll be able to see baby move and groove via ultrasound!) It’s no wonder the first three months are underscored by extreme exhaustion and other less-than-pleasant symptoms (hello, morning sickness and constipation). No one said pregnancy would be easy, so find an OB or midwife you trust, and keep up with prenatal visits and important screenings and tests. The first trimester can feel overwhelming; just take it one day, and milestone to-do, at a time. You’ve got this!

How Long Is the First Trimester?

It might feel like the first trimester stretches on for an eternity, but in reality it starts on day one of your last menstrual period and extends through week 13, day 6. Yes, this means the first trimester includes a brief period when you’re not yet biologically pregnant. It’s a bit confusing, but your medical provider will use the timing of your last period to determine your due date. That means fertilization technically happens around week 2 or 3 and implantation occurs around week 4—so you’ll probably be able to get a positive pregnancy test around week 5. This timeline isn’t definitive, but there’s something reassuring about knowing that the first trimester is well underway by the time you get that positive result.


First Trimester Symptoms

Not sure if you're pregnant? See early signs

The early weeks and months of pregnancy can be physically and emotionally taxing. Those first trimester hormones are no joke, and your body is working hard to grow a human. This means you might feel less than stellar for a while. Of course, pregnancy is a pretty subjective experience. Some pregnant people will have all the symptoms, while others will carry on feeling more or less like their normal, pre-pregnant selves. Odds are, though, you’ll experience at least one or two of the most common first trimester symptoms, including:

Morning sickness

Got that queasy feeling in your tummy? Retching or vomiting is a common affliction in early pregnancy, affecting anywhere from 50 to 90 percent of moms-to-be. A result of rising hCG hormones in your system, morning sickness typically starts a week or two after your missed period and peaks around 9 or 10 weeks. While nagging nausea can persist well beyond the first trimester, most pregnant people get significant relief by week 15. In the meantime, try to hang in there. Eating small, frequent meals can help, as can nibbling on bland carb-centric foods. While you’re at it, be sure to take your daily prenatal vitamin with a mini meal, as this can make a difference too. Need more nausea-quelling tips? Head here for relief.

Bloating and constipation

Well before that adorable bump appears, you’ll feel like your belly has expanded. But in the early weeks of pregnancy, that’s not baby—that’s just bloat. Progesterone, another key pregnancy hormone, relaxes muscles in the gastrointestinal tract, causing a sluggish gut and slow-working digestive system. That can mean uncomfortable gas, bloating and constipation. This is common early in pregnancy but will also come and go throughout the coming trimesters.

Sore breasts

Your breasts may get the memo that you’re pregnant before you do. In fact, they may feel sore as early as two weeks after conception, thanks to a surge in hormones and increased blood flow. This is just the tip of the iceberg; you can expect lots of breast changes throughout the next nine+ months, as your body prepares to birth and potentially feed a tiny new person.

More About First Trimester Symptoms

Learn More: Pregnancy Symptoms

Ready to go beyond the basics? Here you’ll find the latest data, expert insight and proven advice on pregnancy symptoms you may encounter, from your run-of-the-mill side effects to the more uncommon symptoms that may take you by surprise.


Baby Development in the First Trimester

You may not look pregnant for a while, but a lot is happening behind the scenes—and that veritable seed inside your belly will grow by leaps and bounds throughout the next 13 weeks. Cells differentiate to become organs and systems of baby’s body, including the lungs, heart, brain, liver, spine, limbs and genitalia. What’s more, baby’s adorable facial features, toes and even fingernails begin to form in the first trimester.

What to Avoid During the First Trimester

Pregnancy isn’t all fun and games, and there are a few hard rules you’ll have to follow. Here are some things you’ll want to avoid in the coming weeks and months:

  • Smoking and recreational drugs. For starters, you’ll want to quit smoking and cut out any other habits that could pose a danger to baby, such as marijuana or other recreational drug use.
  • Alcohol. Alcoholic beverages are off the table for the next nine+ months. No amount of alcohol is considered safe during pregnancy.
  • Certain foods. Now that you’re pregnant, food-borne illnesses can be particularly harmful. To keep you and baby safe, doctors recommend avoiding foods that can contain bacteria and parasites, including raw meat, fish and eggs; unpasteurised cheese and juice; high-mercury seafood; unwashed vegetables; cold cuts and prepared deli foods. Caffeine is okay in moderation—up to 200 mg a day.
  • Certain chemicals and ingredients. It’s time to take a hard look at the ingredient lists of your skincare, beauty and cleaning products, and avoid things like toxic paint fumes and even kitty litter.
  • Hot tubs, saunas and steam rooms. A long soak or sweat might sound like a heavenly way to rest your tired body, but you’ll want to avoid anything that could raise your core body temperature higher than 102 degrees Fahrenheit, which can be extremely dangerous for your developing baby.

Frequently Asked Questions

First Trimester
Pregnancy is chock full of “what ifs” and nagging questions. Here, we break down a few of the most common first trimester inquiries:

Is it normal to have cramps in your first trimester?


Yes, don’t be surprised if you experience some mild discomfort, similar to menstrual cramps early in pregnancy. It’s possible you might even feel this before your missed period—it could be implantation cramps (this happens when the egg burrows into your uterus). Keep in mind that your uterus is rapidly growing throughout the first trimester and beyond; this can cause a pulling, stretching or cramping sensation. Of course, if abdominal pain is severe or accompanied by heavy bleeding, reach out to your doctor.


When will my bump start to show?


What’s a healthy weight gain range in pregnancy?

First Trimester Checklist

Start taking a prenatal vitamin

Schedule your first prenatal visit—around 8 weeks—and keep up with all regular appointments

Talk to your provider about prenatal genetic testing, and schedule appointments

Ask your provider about any over-the-counter or prescription medications you’re currently taking

Complete non-invasive prenatal testing (NIPT) after 10 weeks, if you’re opting for it

Attend your first trimester screening and/or nuchal translucency ultrasound between 11 and 14 weeks

Review your health insurance plan to see what prenatal and postpartum care is covered

Start eating a healthy, balanced diet, and avoid foods that are potentially dangerous during pregnancy


Johns Hopkins Medicine, The First Trimester

Cleveland Clinic, Ultrasound in Pregnancy, September 2022

Mayo Clinic, 1st Trimester Pregnancy: What to Expect, March 2022

The American College of Obstetricians and Gynecologists, How Your Fetus Grows During Pregnancy, August 2020

Cleveland Clinic, Fetal Development, March 2023

Nemours KidsHealth, Week 2

Maternal and Child Health Journal, Maternal Influences on Nausea and Vomiting in Early Pregnancy, December 2009

Gastroenterology Clinics of North America, Nausea and Vomiting of Pregnancy, June 2011

Cleveland Clinic, Morning Sickness, April 2023

The American College of Obstetricians and Gynecologists, Lower Gastrointestinal Tract Disorders, June 2022

National Institutes of Health, What Are Some Common Signs of Pregnancy?, January 2017

Mount Sinai, Fetal Development

American Pregnancy Association, Pregnancy Cramps

Family Doctor (American Academy of Family Physicians), Changes in Your Body During Pregnancy: First Trimester, February 2021

Cleveland Clinic, Uterus Involution, April 2022

Cleveland Clinic, Diastasis Recti, February 2022

Centers for Disease Control and Prevention, Weight Gain During Pregnancy, June 2022

Centers for Disease Control and Prevention, Substance Use During Pregnancy, May 2022

National Institutes of Health, Substance Use While Pregnant and Breastfeeding, April 2020

U.S. Food and Drug Administration, What Is Foodborne Illness? Food Safety for Moms to Be, September 2018

American Pregnancy Association, Foods to Avoid When Pregnant

The American College of Obstetricians and Gynecologists, Moderate Caffeine Consumption During Pregnancy, August 2010

American Pregnancy Association, Painting While Pregnant

Centers for Disease Control and Prevention, Toxoplasmosis: Pregnancy FAQs, December 2022

American Pregnancy Association, Hot Tubs During Pregnancy

Cleveland Clinic, Pregnancy Tests, November 2022

Mayo Clinic, Prenatal Care: 1st Trimester Visits, August 2022

American Pregnancy Association, Your First Prenatal Visit

U.S. Department of Health and Human Services, Prenatal Care, February 2021

Cleveland Clinic, NIPT Test, October 2022

American Pregnancy Association, First-Trimester Screening

Genetics in Medicine, First Trimester Diagnosis and Screening for Fetal Aneuploidy, January 2008

March of Dimes, Health Insurance During Pregnancy, September 2020


More About the First Trimester

As baby grows in your belly, you’ll want to take the proper precautions to make sure you and baby are safe and healthy. Explore our guides below to learn everything you need to know about pregnancy safety in the first trimester and beyond.


Prenatal care is of the utmost importance right now. Our articles address everything from how to find a trusted ob-gyn to what to expect during your first check-up.


Tracking baby’s fetal development is a wonderful and astonishing part of pregnancy. It’s truly amazing how quickly baby transforms and grows inside the womb.


Feeling overwhelmed when it comes to prenatal testing? We're here to help. From an in-depth guide to non-invasive prenatal testing to explaining what these tests actually screen for, we'll help you through.


Congratulations! Your family is about to grow. If you're starting to wonder about the protocol around pregnancy announcements, we're here to help.


Pregnancy loss can be an emotional and heartbreaking experience. Read our miscarriage articles below to learn more about the different types of loss and how to cope during this trying time.


First Trimester Videos

Sit back and watch videos that cover all things pregnancy. We offer tips and tricks to help you take on your first trimester with confidence.

First Trimester Tools

Whether you need help choosing baby’s name or figuring out your due date, our tools are here to help. Check out our Baby Name Finder, Due Date Calculator, and even a Chinese Gender Chart.


Community Forums

Want to connect with other parents and parents-to-be like you? Join our first trimester forums and birth month clubs to strike up conversations, ask questions and find advice and support from others.

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