The most mind blowing thing about your first trimester is that it begins before you are actually pregnant! (Pregnancy math is, by far, the weirdest math of all.) That means your initial first trimester symptoms are actually menstrual symptoms, like cravings, bloating, and breast tenderness. And since the first trimester stretches from the first day of your last menstrual period to 13 weeks of pregnancy, you’ve got plenty of time to experience first trimester pregnancy symptoms…and there are a lot! After all, your body is suddenly tasked with building a whole new human, which takes a ton of energy and work. To get the ball rolling, your body is flooded with hormones, your uterus begins to expand, the amount of blood that rushes through your body increases, and more. How does all of this translate into first trimester pregnancy symptoms? Keep reading to find out!

What is the first trimester of pregnancy?

Pregnancy is divided between three distinct stages called trimesters. Each trimester is about three months long. But by the time you know you’re pregnant, you likely already zipped through the four full weeks of your first trimester! That’s because your first trimester begins on the first day of your last menstrual period (LMP)...before you’re even pregnant. (To calculate your due date, your provider adds 40 weeks to the first day of your LMP.) Adding to the confusion, not all experts agree when the first trimester ends. This guide adheres to the American College of Obstetricians and Gynecologists (ACOG) statement that your first trimester of pregnancy lasts until the end of week 13 of pregnancy.

First Trimester Symptom: Breast Changes

Even though you’re still a long way off from breastfeeding, an influx of estrogen and progesterone encourages your breasts to start preparing now. In fact, early in your first trimester, these hormones team up to increase what’s called ductal branching, which is a tree-like network of ducts that are readying to transport breastmilk to your nursing baby. At the same time, pregnancy hormones broaden your mammary glands, causing swelling and tenderness—and they work to enlarge and darken your areolas, which are the pigmented areas around your nipples. (It’s thought that these areola changes make it easier for your little one to find milk fast!)

During the first trimester you’ll start to notice wee white bumps around your areolas. These are called Montgomery’s tubercles and they’re enlarged sweat glands that’ll eventually produce oily secretions to help prevent your nipple and areola from cracking while breastfeeding. (Fun fact: The oil smells like amniotic fluid, so that your newborn will recognize and feel comforted by the familiar aroma.) Finally, the uptick in blood flow, means the veins in your breasts are now way more noticeable than pre-pregnancy. The good news is that breast soreness usually fades once your body has a chance to acclimate to the hormone influx. In the meantime, wear a comfy, cotton bra that offers good back and side support—and consider wearing a sleeping bra.

First Trimester Symptom: Bleeding and Spotting

Light bleeding or spotting during the first trimester can be scary, but it’s usually nothing to worry about. Experts note that elevated hormone levels alter the surface of the cervix, which can make you more susceptible to bleeding. About 15% of moms-to-be who bleed or spot during their first trimester do so around the time of their expected menstrual period, according to a report in the journal Annals of Epidemiology. This type of early first trimester pink or brown spotting is called implantation bleeding, and it’s a sign that a fertilized egg has implanted into your uterine lining. Implantation bleeding can be a brief one-time thing, or it may linger for about three days. If spotting stops within a day, simply let your healthcare provider know at your next prenatal visit. But if the bleeding extends longer—or is heavier, features clots, and/or is accompanied by abdominal pain, cramping, fever, or chills—call your healthcare provider immediately.

First Trimester Symptom: Increased Urination

Right about now, you may find yourself scoping out the nearest bathroom wherever you go. That’s because the increased need to pee is a common first and third trimester pregnancy symptom. (You are granted a brief reprieve in the second trimester.) In the third trimester, your growing uterus puts the squeeze on your bladder, which prompts frequent bathroom visits. But during the first trimester, a spike in hCG, or the human chorionic gonadotropin hormone is the reason for all those pee breaks. This hormone not only enhances blood flow to your nether regions, it likely also triggers your kidneys to work overtime, encouraging all those trips to the bathroom.

While there’s nothing you can do about all the hCG flowing through your body, practicing Kegel exercises can help strengthen your pelvic floor and make your bladder a little less reactive. At the same time, it’s a wise idea to drink most of your water during the day and avoid beverages too close to bedtime. This can help you middle-of-the-night bathroom runs.

First Trimester Symptom: Nausea

Morning sickness is one of the most common telltales of early pregnancy, impacting between 70 and 90% of moms-to-be. The worst of it usually strikes between 8 to 10 weeks of pregnancy, with the nausea and vomiting often tapering off by the end of the first trimester. It’s believed that hCG—the hormone behind all those first trimester bathroom visits—may be at least partly responsible for morning sickness. Produced when a fertilized egg attaches to the uterus, hCG continues to rise through the first trimester, then declines for the rest of your pregnancy 

Studies have linked high levels of GDF15, a cellular stress hormone found in the placenta, to first trimester nausea and vomiting, too. Apparently, GDF15 is responsible for sending signals to the part of the brain that controls nausea and appetite. While morning sickness can strike in nearly any pregnancy, certain factors may increase your chances of severe morning sickness, such as carrying multiples, a history of motion sickness or migraines, sleep deprivation, and having a BMI greater than 25 or less than 30.

To help quell this common first trimester pregnancy symptom, get as much rest as you can, avoid laying down after eating, drink 8 to 12 cups of water a day to avoid dehydration that can make nausea worse, and consider aromatherapy. Smelling fresh lemon, orange, and mint has shown to help quell nausea. Certain dietary tweaks may help curb nausea, as well, but don’t hesitate to speak to your doctor about supplements or medication.

First Trimester Symptom: Fatigue

Yawning through your first trimester? You’re not alone. Among 600+ expectant mothers surveyed, more than 94% reported feeling fatigued during pregnancy. Take your newfound exhaustion as a signal that your body is working extra hard and needs some time to adjust to its new job as a Baby Builder. Right now, the “passive work” of creating a placenta, plus the sharp uptick of your blood volume and the hormone progesterone are leading the pregnancy fatigue charge. But as you grow accustomed to these changes, your first trimester fatigue will usually recede so you can enjoy a burst of energy in your second trimester.

To feel better, aim for eight hours of sleep each night—and sneak brief naps during the day, if you can. Try to eat three meals and two to three snacks daily featuring healthy proteins to help keep your blood sugar stable and your energy up. It’s a good idea to move your body regularly, which will help energize you—and may even help you rest better at night. (Learn more about first trimester fatigue and how to feel more awake.)

First Trimester Symptom: Food Cravings

Studies show that 76% of moms-to-be experience at least one pregnancy-related food craving by the end of the first trimester. (The same report notes that sweets, cheese, starchy carbs, fruit, and fast food are among the most desired eats.) It’s thought that pregnancy food cravings may be connected to hormone fluctuations that affect your perception of foods—or craving may simply boil down to cultural expectations. Translation: If you expect to crave ice cream in pregnancy, you may feel okay about a freezer full of Ben & Jerry’s.

But there’s no scientific evidence to support the notion that foods are craved due to their nutritional value. Some research, like the study in the Journal of Human Nutrition and Dietetics, reports pregnancy cravings are only responsible for a small increase in caloric intake. Other research notes that frequent cravings in pregnancy are a strong predictor of excess weight. No matter which is accurate, it’s a good idea to seek out nutrient-dense foods that satisfy your pregnancy cravings. Find the healthiest way to scratch your pregnancy craving itch.

First Trimester Symptom: Food Aversions

The cruel flip side of pregnancy cravings is pregnancy food aversions, which strike nearly 70% of moms-to-be and begin to emerge during the first trimester. With pregnancy food aversions, the taste, smell, or even the sight of a particular food turns your tummy for reasons not completely understood…but there are plenty of theories! For one, progesterone slows digestion, which may make harder-to-digest fried or high-fat foods suddenly unappetizing in pregnancy. At the same time, about 93% of expecting parents experience a sour or metallic taste in their mouth and roughly 65% have a heightened sense of smell, making certain aromatic foods especially nauseating. 

If you have a pregnancy aversion to, say, buffalo chicken wings, but you’re still able to get all the nutrients you need from other sources, don’t worry about your sudden distaste of bar food. However, if your food aversions are taking a significant toll on your healthy eating, you can learn strategies to eat around your aversions. For example, adding citrus or sauces—or marinating—meat helps cut down on the metallic flavor. The good news is pregnancy food aversions often (but don’t always) disappear along with morning sickness during the second trimester.


First Trimester Need-to-Knows:



  • Cleveland Clinic: Menstrual Cycle
  • Cleveland Clinic: First Trimester
  • American College of Obstetricians and Gynecologists (ACOG): How Your Fetus Grows During Pregnancy
  • John Hopkins Medicine: The First Trimester
  • Characterization of breast changes in the early gestational period on automated breast ultrasound. Journal of Medical Ultrasonics. October 2023
  • Arizona Department of Health Services: Normal Breast Changes in Pregnancy
  • Anatomy, Thorax, Mammary Gland. StatPearls. December 2023.
  • Cleveland Clinic: Am I Pregnant?
  • Kaiser Permanente: Breast Changes During Pregnancy
  • The University of Chicago Medicine: Tips for managing pregnancy symptoms by trimester
  • Patterns and predictors of vaginal bleeding in the first trimester of pregnancy. Annals of Epidemiology. July 2010
  • Mayo Clinic: Bleeding during pregnancy
  • Cleveland Clinic: Frequent Urination
  • Huron Regional Medical Center: Pregnancy and the Urge to Pee
  • Cleveland Clinic: Morning Sickness
  • Hyperemesis Gravidarum. StatPearls. July 2023
  • Mayo Clinic, Pregnancy week by week: 1st trimester pregnancy: What to expect
  • GDF15 linked to maternal risk of nausea and vomiting during pregnancy. Nature. December 2023
  • ACOG: Morning Sickness: Nausea and Vomiting of Pregnancy
  • Fatigue and sleep quality in different trimesters of pregnancy. Sleep Science. Jan- March 2021
  • Penn Medicine Lancaster General Health: Is This Normal? Pregnancy Exhaustion Edition
  • John Hopkins Medicine: First Trimester Fatigue
  • Pickles and ice cream! Food cravings in pregnancy: hypotheses, preliminary evidence, and directions for future research. Frontiers in Psychology. September 2014
  • Houston Methodist: Pregnancy Cravings: What Do They Mean and What Should You Do?
  • Nutritional and clinical associations of food cravings in pregnancy. Journal of Human Nutrition and Dietetics. June 2016
  • Food cravings in pregnancy: Preliminary evidence for a role in excess gestational weight gain. Appetite. October 2016
  • Cleveland Clinic: Food Aversion
  • Changes in Gustatory Sense During Pregnancy. Acta Oto-Laryngologica. July 2009
  • Michigan Medicine, Univeristy of Michigan: Prenatal Nutrition: Healthy Eating Tip of the Month

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.