Your Baby’s Journey in First Trimester: An Easy Month by Month Guide

Having a baby is an amazing feeling and so is the 10-month long journey. For you to feel a new life growing inside your belly and your body working tirelessly to support this unique process is an incredible experience.

For every pregnant woman, this journey is unique. However, knowing the changes that your body witnesses during this phase can smoothen mental and physical transitions.

Your Baby’s Journey in First Trimester: An Easy Month by Month Guide

In this article, you will learn about the changes that your body and fetus undergo during the first trimester.

Start of the journey

Your pregnancy begins with the first day of your last menstrual period. However, conception occurs two weeks after this period.

Conception is the period in which fertilization occurs. Typically, a female ovary produces a group of eggs every month out of which one mature egg is suitable for fertilization. Fertilization occurs when a sperm penetrates the mature egg.

Fun Fact: Your baby’s genetic make-up is determined at this stage including its sex.

Did you know? Fertilization occurs in the fallopian tube where the egg remains for approximately three days and divides itself into multiple cells — post which fertilized egg shifts to the uterus and continues to grow.

In the uterus, egg undergoes implantation (a process in which egg attaches itself to the inner membrane lining of the uterus).

Did you know? Your baby is called an embryotill 8th week of pregnancy and after 8th week till the moment of birth, it will remain a fetus.

Pregnancy is divided into three trimesters. Each trimester is a 3-month long period and the first month marks the beginning of the first trimester.

Let’s talk about your baby’s journey in the first trimester

Month 1 (Week 1 to Week 4)

Post-fertilization and implantation, the embryo continues to grow and develops a white-tight sac around itself. This white sac, also termed as the amniotic sac, is filled with fluid and provides cushioning to the developing embryo.

At this stage, the placenta also develops. Placenta is not only responsible for the transfer of growth nutrients from the mother to the fetus but also for disposal of fetal waste.

During the first month, facial features start developing. The face begins to form along with dark circles for eyes. The mouth, lower jaw, and throat also start developing. Blood cells start forming, and blood circulation begins.

At the end of the first month, your baby is as big as a grain of rice and ¼ inch long.

Month 2 (Week 5 to Week 8)

During week 5 to week 8, most of the facial features start developing. Along with face, eyes, eyelids, mouth, and jaws, ears also begin developing little folds of skin at the side of the head. At the place of arms and legs, tiny buds start to form. Fingers and toes also start developing.

At this stage, the neural tube which includes brain, spinal cord and neural tissues of the central nervous system is well-developed. Bones have started replacing cartilage, and digestive plus sensory organs have begun to form as well. At this stage, the umbilical cord also starts developing.

During this period, your baby’s head is larger than the rest of the body and has a fully functional heart.

At the end of the second month, your baby is about 1-inch long and weighs less than a gram.

Month 3 (Week 9 to Week 12)

The umbilical cord is now fully-functional and now connects the fetus to the placenta and uterus wall. Your baby is no longer an embryo. It has transformed into a fetus now.

Your baby’s tail has now disappeared and has fully formed arms, hands, fingers, feet, and toes. Most of the organs have taken shape and will continue to mature to become functional. Your developing baby can now open and close its fists and mouth. Features like fingernails, toenails, and teeth start forming.

Reproductive organs have also started developing, but it is hard to distinguish the gender at this stage. The circulatory and urinary system has begun working, and the fetus has a fully-functional lever.

At the end of the first trimester, your baby is about 4 inches long and weighs approximately 28 grams.

Caution! The first trimester is critical for your baby

Most of the fetal development takes place during the first three months of the pregnancy, including significant hormonal and physical changes. Since your body is adjusting itself to support the new life and is working tirelessly, it is vital to take care of your mental and physical well-being.

Chances of miscarriage are high during this time due to the physical and hormonal changes in your body. Post first trimester, your chance of miscarriage drops significantly.

What are the symptoms of pregnancy during the first trimester?

The first sign of pregnancy is a missed period. However, symptoms of pregnancy generally witnessed during the first trimester includes:



         Mood Swings



         Swollen/Tender Breasts


         Weight Gain

Not every pregnant woman has these symptoms. But, it’s common to have them.

Here is the checklists for tests that should be done during 1st trimester

There are multiple tests and scans that you will be advised to undergo during your pregnancy during the first trimester, including.

  1. Pregnancy test: Your doctor will perform a confirmatory pregnancy test by checking hCG (a pregnancy hormone) level in your urine.
  2. Blood test: This test is performed to check your blood type, Rh factor, Anemia, Hepatitis B, Syphilis, HIV, Rubella, Chicken Pox, Cystic Fibrosis, and Spinal Muscular Atrophy.
  3. First-trimester screening: This test is a combination of blood test & ultrasound examination and helps determine the risk of chromosomal abnormalities (such as Down syndrome) or congenital disabilities (such as a heart problem) in the fetus.
  4. Ultrasound: This is one of the safest ways to check fetal development and is done early in the first trimester. If you have a high-risk pregnancy, you will be advised for multiple ultrasounds during the first three months.
  5. Chorionic villus sampling (CVS): This test is performed to determine the chromosomal abnormalities (such as Down syndrome) in the fetus by checking placental cells.
  6. Cell-free DNA testing: This is a blood test that checks for fetal DNA in the mother’s blood and is performed to determine chromosomal disorders.

Few of the other tests include checkups for Thyroid, Hepatitis C, Cytomegalovirus (CMV), Toxoplasmosis, Tay-Sachs disease, Tuberculosis, Fragile X syndrome, and Canavan disease. 

Prenatal tests are crucial to check mother and baby’s health, hence, it is vital to get your Prenatal Screeniing tests done from trusted diagnostic providers. LifeCell Diagnostics with over 200+ centers and 1200 hospital partners is India’s one of the biggest and high-tech diagnostic labs in India. They are also the first in the country to offer an extended first-trimester Penta marker screening, a comprehensive prenatal screening.

The pentastic test has a high detection rate of 98% and helps doctors detect the possibility of pre-eclampsia during the initial pregnancy phase. This test is also cheaper than NIPS and provides approximately the same detection rate.

Post checkups, don’t forget to ask your doctor about below-mentioned checklist:

  1. Physical care that you need to take during the first three months.
  2. Food that you should eat or avoid during this course.
  3. Exercises or physical activity that you should perform during this time.
  4. Medicines or supplements that you should take or avoid.
  5. Though it’s early, check the importance of Stem Cell banking and why you should consider it.

Disclaimer : Content presented here is for information purposes only, please consult with your doctor for any health queries

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