iCliniq logo

Ask a Doctor Online Now

HomeHealth articlespregnancyWhat Changes Occur During the First Trimester of Pregnancy?

First Trimester of Pregnancy - What to Expect

Verified dataVerified data

4 min read


During the first trimester of pregnancy, major development of the fetus occurs. Read this article to know more about the changes happening in this stage.

Written by

Dr. Asha. C

Medically reviewed by

Dr. Richa Agarwal

Published At September 16, 2022
Reviewed AtFebruary 8, 2023


The full-term pregnancy lasts about 40 weeks and is divided into three trimesters. The first trimester starts from the first day of the last period and lasts until the end of the 13th week. Understanding a pregnancy week by week can help you prepare for the changes ahead and make informed decisions.

What Are the Changes That Happen in the Body During the First Trimester of Pregnancy?

Every pregnancy is different, and so are the experiences. During the first trimester, many changes will happen to the body, which helps protect and nourish the baby. Some pregnancy symptoms continue for many weeks or months while others symptoms are only experienced for a short time.

The following are the lists of symptoms and changes that may happen during the first trimester:

  • Tenderness of the Breast - Tender breast is one of the early symptoms of pregnancy. Due to the enlargement of the mammary glands, the breasts swell and become tender in preparation for breastfeeding. The breasts will be most sore throughout the first trimester. Using a large bra size or wearing a support bra can be helpful.

  • Morning Sickness - It is one of the most common symptoms of pregnancy. It is due to hormonal changes in the body, and it can last through the entire first trimester. Nausea is usually worse in the morning. Nausea is a common symptom, and there is nothing to worry about, but if it is severe or lasts for a long duration, it can affect the amount of nutrition the baby gets.

  • Constipation - Increased levels of the hormone progesterone slow down the muscle contractions that normally move food through the digestive system. Iron supplements can also result in uncomfortable constipation. Consuming more fiber and drinking extra fluids help to relieve constipation.

  • Tiredness - The mother’s body is working hard to nourish a growing baby. This is the reason for tiredness. Taking proper nutrition helps to prevent fatigue.

  • Vaginal Discharge - Thin, milky white discharge is common in early pregnancy. If the discharge smells really bad or green or yellow colored, then consult a physician.

  • Bleeding - In the first trimester of pregnancy, light spotting or bleeding may be due to the fertilized embryo implanting in the uterus. If the bleeding is heavy and continuous or accompanied by cramping pain, it may be a sign of miscarriage.

  • Heartburn - During pregnancy, the body produces more of the hormone progesterone that relaxes the smooth muscles of the lower esophagus (the tube that connects the mouth and stomach). These muscles normally keep food and acids down in the stomach. When the muscles get to loosen up, acid reflux happens to cause heartburn.

What Are the Changes in the Fetus During the First Trimester?

During the first trimester, the baby changes from a fertilized egg into a fully-formed fetus. These are the following changes that happen to the fetus,

Development in 4 Weeks -

  • In this stage, the embryo looks like a tadpole.

  • The major organs and systems begin to develop, like the neural tube, the heart and circulatory system, and the digestive system.

  • The eyes and ears start to develop.

  • Tiny limb buds appear, which form future arms and legs.

  • The heartbeat starts appearing in this stage.

Development in 8 Weeks -

  • There is the continuous development of major body systems,

  • The embryo starts taking on a human shape.

  • Development of the mouth and tooth buds happens.

  • The eyes, mouth, nose, and ears are becoming more distinct.

  • The arms and legs can be easily visible in ultrasound, and the fingers and toes look webbed but can be distinguished.

  • The baby's heartbeat can be heard using Doppler.

  • The bones begin to develop.

  • The nose and jaws grow rapidly.

Development During 9 to 12 weeks -

  • The genital organs develop during this week.

  • Eyelids, fingernails, and toenails appear.

  • Increased fetal movements happen.

  • Full development of arms and legs takes place.

  • The voice box begins to form in the trachea.

The embryo is called a fetus after eight weeks. All the major organs and systems develop at this stage.

What to Expect During the First Prenatal Visit?

The first prenatal visit may include:

1) Medical History -

  • Record of any medical conditions, like diabetes, blood pressure, anemia, or any allergy.

  • Previous history of surgery, trauma, and current medications.

  • Paternal family medical history, including illnesses, genetic disorders, and intellectual or developmental disabilities.

2) Gynecological and Obstetrical History - Doctors take a record of past pregnancies, stillbirths, deliveries, miscarriages, terminations, and menstrual history.

3) Pelvic Exam - It is done to note the size and position of the uterus, determine the age of the fetus, and check the pelvic bone size and structure.

4) Lab Tests -

  • Urine Tests - These are done to screen for glucose, bacteria, and protein in the urine.

  • Blood Tests - These are done to determine your blood type and Rh factors.

  • Blood Screening Tests - These are done to check any diseases that could have an effect on the pregnancy, like rubella.

  • Genetic Tests - These are done to check inherited diseases, like sickle cell disease.

5) Ultrasound - To confirm pregnancy and check the growth of the fetus.

What Should Be Followed During Pregnancy?

A to-be mother should be careful to avoid any mishappens in the first trimester. These are the things to be considered during early pregnancy:

  • Consult a gynecologist soon as you know you are pregnant.

  • Continue with prenatal visits every 4 weeks. The doctor will check your weight and blood pressure, test your urine and listen to your baby’s heartbeat.

  • Take vitamin supplements and folic acid to help the baby’s brain and spinal cord growth.

  • Take a look at your diet and make any changes you need to make sure you and your baby get the right nutrition. Drink plenty of water.

  • Eat a diet high in fruits, vegetables, low-fat forms of protein, and fiber.

  • Drink lots of water.

What Should Not Be Followed During Pregnancy?

During pregnancy, few foods should be avoided, and a few lifestyle changes should be mandatory which include:

  • Avoid using illegal drugs and quit smoking.

  • Do not do strenuous exercise or strength training.

  • Avoid food like raw fish or smoked seafood and fish with high levels of mercury.

  • Do not touch cat litter, which can carry a parasitic disease called toxoplasmosis.

  • Do not use unpasteurized milk or other dairy products.

Conclusion -

The first trimester is crucial because, during this period, the development of major organs happens, and it can be damaged if the baby is exposed to drugs, tobacco, infectious agents, radiation, certain medications, and toxic substances. So proper care and diet are important for both mother and fetus health.

Frequently Asked Questions


What Happens During the First Trimester of Pregnancy?

The first three months of pregnancy are marked by changes in hormones, sickness in the morning, changes in the breasts, tiredness, and the growth of the baby's main organs and systems.


What Should Be Avoided in the First Trimester?

It is recommended that women should stay away from consuming alcohol, smoking (including secondhand smoke), drugs (including some prescribed prescriptions), eating foods that are raw or undercooked, drinking large amounts of caffeine, or eating fish that is high in mercury during the first trimester of pregnancy.


What Week Is the First Trimester of Pregnancy?

Weeks 1–12 make up the first trimester of pregnancy.


How Should I Sleep in the First Trimester?

In the first three months of pregnancy, it is best to sleep on the side, or the left side, to reduce strain on the heart and other vital organs and increase blood flow to the baby.


How Can I Have a Successful First Trimester?

Prenatal vitamins, a healthy diet, plenty of water, regular exercise, stress management, and regular prenatal checkups are all essential for a healthy first trimester of pregnancy.


What Food Is Good in the First Trimester?

Foods rich in folate and iron, along with a wide variety of fruits and vegetables, healthy grains, lean meats, dairy products, and other healthy foods, are all recommended throughout the first trimester of pregnancy.


Where Is The Baby Located At Four Weeks?

At four weeks, most pregnancies have progressed to the point where the embryo is implanted in the uterine lining.


How Does the Stomach Feel in the First Trimester of Pregnancy?

In the first three months of pregnancy, some women experience dizziness and vomiting.


How Uncomfortable Is the First Trimester?

Some women experience more severe exhaustion, breast discomfort, frequent urination, and morning sickness during the first trimester of pregnancy than others.


Is First Trimester Pregnancy Very Hard?

Each woman experiences the first trimester of pregnancy uniquely. Some women may have more difficulty with it than others because of symptoms like morning sickness and extreme exhaustion.


When Should I Tell My Husband I Am Pregnant?

One can decide when is the best time to break the news of being pregnant to one another. There is no set schedule because it all relies on preferences.


Are Pregnant Women Always Sleepy?

Due to hormonal changes and the increased energy needs of pregnancy, fatigue, and increased drowsiness are frequent, especially during the first trimester.


What Is Most Harmful During Pregnancy?

Smoking, drinking, illicit substances like drugs, some prescriptions, environmental pollutants, and untreated medical disorders are the most dangerous things to do during pregnancy. The mother's and baby's well-being must be prioritized first.


What Activities Should I Do to Avoid Getting Pregnant?

Heavy lifting, contact sports, extreme exercise, toxic substance exposure, and high-risk jobs are all things pregnant women should stay away from.


Which Vegetables Are Avoided During Pregnancy?

Raw sprouts (including alfalfa sprouts) and other unwashed raw vegetables should be avoided during pregnancy due to the risk of bacterial contamination. However, if they are washed and cooked correctly, most veggies can be eaten safely and benefit a pregnant woman.


When Should I Stop Bending During Pregnancy?

After the first trimester (about 12-14 weeks), pregnant women are advised to avoid heavy lifting and bending from the waist to prevent the risk of strain or injury.
Dr. Richa Agarwal
Dr. Richa Agarwal

Obstetrics and Gynecology


Community Banner Mobile
By subscribing, I agree to iCliniq's Terms & Privacy Policy.

Source Article ArrowMost popular articles

Ask your health query to a doctor online

Obstetrics and Gynecology

*guaranteed answer within 4 hours

Disclaimer: No content published on this website is intended to be a substitute for professional medical diagnosis, advice or treatment by a trained physician. Seek advice from your physician or other qualified healthcare providers with questions you may have regarding your symptoms and medical condition for a complete medical diagnosis. Do not delay or disregard seeking professional medical advice because of something you have read on this website. Read our Editorial Process to know how we create content for health articles and queries.

This website uses cookies to ensure you get the best experience on our website. iCliniq privacy policy