First trimester

Did your heart just skip a beat when you saw “Positive” on your pregnancy test kit? Did you feel butterflies in your stomach, yet somewhere deep down you were a bit nervous because you do not really know how things will work out? Is this the first time you are going to become a mommy? If your answer to all these questions is in affirmative, this article is most definitely for you! First of all, calm down, take a deep breath and go through this, for there is actually nothing you should worry about so much! You can be rest assured for at least the first three months because we are going to tell you all about the first trimester of one of the most memorable periods of your life!

pregnency test




What is the first trimester?

As the very name suggests, if your entire pregnancy period of approximately nine months is divided into three equal parts, the first three months of your pregnancy fall into the first trimester. Technically speaking, the first trimester encompasses the span of time starting from the first day of your last menstrual period to the twelfth week of your pregnancy. Surprisingly enough, by the time you are absolutely sure of the “good news” in your life, you are probably almost into the midst of your first trimester!

This is because for the hormone levels to change enough so that the pregnancy is reflected in the tests and to provide you with ample symptoms, it already takes about four to five weeks from conception. There are a lot of changes that take place in this period.

The process of cell division, in fact starts right from the moment the egg is fertilized by the sperm. The fertilized egg, now known as the zygote, starts dividing into several layers of cells and gets implanted into the uterine wall, which will be the home of your baby for the next 9 months. This is when the zygote becomes and embryo, which is your baby’s name in this period.

developments in the first trimester

Developments in the First Trimester

Weeks 1 and 2 of the first trimester

It might sound surprising to you, but you have not actually conceived your baby during these two weeks, although these are counted in the span of your pregnancy. So this period is actually two weeks from your last menstrual period and your baby is yet to be conceived.




Not that you are pregnant, it’s really important to know what to eat when pregnant and what not to eat when pregnant.

week 1 and week 2 first trimester

Week 3 of the first trimester

This is basically when due to sexual intercourse, the process of fertilization will occur. The egg cell and the sperm cell unite in one of the fallopian tubes to form what is known as the zygote which has 46 chromosomes- 23 from the mother and 23 from the father. Soon after this, the zygote travels, through the walls of the fallopian tube, to the uterus, ready to be implanted.

week 3 during first trimester

Week 4 of the first trimester

This is when the process of implantation actually takes place. By this time, the embryo has rapidly divided its cells and is now known as the blastocyst, ready to burrow itself into the uterine wall. The inner part of the blastocyst remains to be the embryo and the outer part will give rise to the placenta which will nourish the baby throughout your pregnancy.

Week 5 of the first trimester

This is when the secretion of HCG hormones in your body increases rapidly, signaling the uterus to produce more estrogen and progesterone. Increased levels of these hormones stop your menstrual period, which often one of the first signs of pregnancy. They also fuel the growth of placenta for proper nourishment of the embryo. The embryo now has three distinct layers:

 Ectoderm – This will lead to the formation baby’s outer layers of skin, central and peripheral nervous systems, eyes, and ears.
 Mesoderm – This layer gives foundation to your baby’s heart, primitive circulatory system, bones, ligaments, kidneys and much of the reproductive system.
 Endoderm- This is where the baby’s lungs and intestines will be formed.

Week 6 of the first trimester

This is when the baby’s brain and spinal cord will be formed from neural tube.
Structures leading to the development of the eyes and ears also begin to develop during this time. Small buds also begin appear that later become arms. The baby gradually begins to shape into a C-shaped structure as later seen during sonographies.




week 6 of first trimester

Week 7 of the first trimester

You’re seven weeks into your pregnancy and your baby’s brain and face start to develop. Depressions that will give rise to nostrils become visible, and the foundations of the eye’s retinas begin to form. The lower limb buds that are become legs begin to appear and the previously sprouted arm buds now develop their actual shape.

Also read: Second Trimester and Third Trimester explained week by week.

Week 8 of the first trimester

Now, baby’s lower limb buds take their shape. Fingers are beginning to form. Foundations to your baby’s ears develop and the eyes become visible. The upper lip and the nose are now completely formed! The neck too begins to straighten. The baby is now almost half an inch long from the crown to the rump.

Week 9 of the first trimester

This is when your baby’s arms grow and elbows begin to appear. The toes and eyelids are also formed. Although the head is large, your baby surprising still has a poorly formed chin.

Week 10 during the first trimester

Your baby’s head will gradually now take its round shape and he/she can now bend his/her elbow. Toes and fingers take their shape too. Eyelids and external ears still develop. The umbilical cord which is the main connection between you and your baby is now clearly visible.

Week 11 during the first trimester

This is the period by the end of which your baby’s sex organs will be developed! The red blood cells begin to form in the liver. Now, the face and the eyes are distinct, and the eyelids and ears too are developed. Congratulations! Your baby can now officially be called a fetus!

Week 12 during the first trimester

You’re twelve weeks into your pregnancy, and your baby has now grown his/her fingernails. The face further develops and his/her intestines are developed in the abdomen. He/she is now two and a half inches long from crown to rump!

Change in your lifestyle during the first trimester

No matter how difficult it is for you to accept, now that you’re about to bring another new life to this world, there are certain changes that you have to adapt to right from the first trimester, whether you like it or not! To start with, you will now have to make your gynecologist your best friend. As we all know, “It is better to be safe than sorry”, and hence it is always better to consult him/her whenever in doubt.

The obvious things that you have to give up is smoking, drinking, self-medication and intake of caffeine. Listening to some good music, doing what you love to do and devoting some time to relaxation and yoga might help you keep fit mentally and physically.




Effects on your health during the first trimester

There is no use denying the fact that early days of pregnancy will surely take a toll on your physical health right from the first trimester itself and let me tell you that is perfectly normal. Symptoms such as nausea, morning sickness, cramps and indigestion are completely fine and nothing to worry about. However, do not forget to consult your new best friend (Read: Gynecologist) if it bothers you too much.

effects on health during first trimester

Please remember that your mental health is also equally important. It is perfectly okay to feel low and down at times. Try speaking your mind out to someone you trust. I promise it will be fine with time.

Do not forget that this is a journey you will surely cherish for the rest of your life. So, laugh and be merry, your happiness will surely be contagious!




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