What to Expect During Your First Trimester of Pregnancy

Growing a little human brings on a lot of change: changes for your baby and changes for you, both physically and emotionally. If this is your first time being pregnant, or even if you just need a refresher, here’s what you can expect during your first trimester.

By Dr. Kenosha Gleaton

How long is the first trimester?

The first trimester begins on the first day of your last period and ends with the thirteenth week. Thus, many women are half way through the first trimester before discovering they're pregnant! Whether your mom-to-be status is discovered early or late, we're here to help you navigate this exciting yet often daunting time. Keep reading!

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The initial doctor’s visits

Once your pregnancy is confirmed, a thorough prenatal visit should follow. Your initial visits will include:

1. Medical history, including medications, prior surgeries, past pregnancies, partner’s history, and family history
2. Physical exam, including breast exam, pap smear, possible sexually transmitted infection (STI) testing, and blood pressure check
3. Imaging, including an ultrasound to confirm your best due date
4. Lab tests, ruling out pre-existing medical conditions
5. Education, covering nutrition, exercise, sleep, and harmful substances
6. Counseling, regarding options for genetic testing during pregnancy

Changes for mom

Three months of pregnancy means three months of intense change. After an embryo attaches to the uterine wall, the amniotic sac, placenta, and umbilical cord develop. The amniotic sac contains fluid to protect and regulate the fetus, while the placenta provides fetal nutrients and eliminates waste. The umbilical cord connects the fetus and the placenta and transports nutrients and waste back and forth. 

Such intense physical changes can impact your energy as well as your emotions—both of which can be quite unpredictable. 

Here’s what you’ll likely experience early on:

• Missed period
• Sore breasts
• Fatigue
• Changes to your skin
• Discharge or spotting  
• Frequent urination
• Cramping
• Nausea and possibly vomiting

Closer to your 13 week mark, you can expect:

• Cravings or aversions 
• More visible veins
• Unpredictable moods
• Constipation
• Heartburn

Changes for baby

The first four weeks of pregnancy establish the fundamental development for every system of the growing embryo. The neurologic, circulatory, cardiovascular, and musculoskeletal system all begin to form. This translates into your pea-sized embryo having a brain, spinal cord, lungs, and limb buds at the conclusion of the first month. 

And throughout the entire first trimester, big changes are happening to an embryo. The nervous system and the heart are starting to develop, and vaginal ultrasounds can likely pick up a fetal heartbeat. Halfway through the first trimester, a fetus is the size of a pea, and the formation of nostrils, eyes, and limbs is evident.  

Closer to the end of the first trimester, the eyes will be fully developed (but will remain closed), the placenta will grow to about one and a half pounds, and limb bones will begin to form. Eventually, the fetus will weigh about an ounce, be about three inches long, and be nearly the size of a lemon. 

Six ways to prepare for a healthy pregnancy

1. You should be taking a prenatal vitamin ASAP if you aren’t already! This is so important for the growth of your baby and for your own health. We offer our Natalist Prenatal Daily Packets subscription so you can ensure you’re getting the best nutrition possible each and every month. 
2. Organic ginger candy can be helpful for settling morning sickness and digestive issues.
3. Read What to Eat When You’re Pregnant for recipes and information on keeping you and your baby healthy. 
4. Read Parent Plans to cover all your bases, from baby names to finances. 
5. If you’re putting off buying those maternity pants, these waistline extenders can help you fit into your favorite pants and skirts when that baby bump starts showing. 
6. Make a doctor’s appointment. If you know or expect that you’re pregnant and you haven’t seen a doctor, you should make an appointment ASAP. It’s vital to find a provider you’re comfortable with to establish care for your  prenatal visits. 

From gazing at your baby's first ultrasound to announcing your pregnancy to the world, there’s lots to do in the first three months of pregnancy. Although everyone’s journey is vastly different, the desired destination is the same. Check out our other pregnancy articles for more information, support, and answers to common questions.