Development of your baby in the First Trimester

In order to understand and experience every day of your first trimester, let’s take a look at a week by week development breakdown of the most important trimester of your pregnancy.

The first few weeks of your pregnancy are the most crucial for you and your baby. This is the time period when your fetus starts to develop its organs and its heart starts beating. Apart from the joy that you feel of having a little one in your womb, you also feel symptoms of hormonal changes in the body. Sometimes you wake-up feeling nauseous, and other times you are just digging into an ice-cream tub. However, not everyone comes across the same experience during the first few weeks of their pregnancy.

First Week of Trimester

Week one is the most initial part of your pregnancy. You are not pregnant in the first week because your baby is still in the form of an egg residing in your ovaries. You have not yet conceived, because you are on your periods. Doctors count the pregnancy from the start of your period because it takes time for the egg to release.

Second Week of Trimester

This is the time when your period stops, and the lining of your uterus begins to thicken. The Progesterone levels in your body also begin to rise, and there are many blood vessels being laid inside your uterus. The egg in one of your ovaries is preparing to release. At this time, you don’t feel or know anything that is going on inside your body.

Third Week of Trimester

This is the week that you have been waiting for. The third week of your first trimester is when you conceive and take a test to find out whether you are pregnant or not. The egg in your ovaries is ready to settle in your womb. This is the time when the Human Chorionic Gonadtrophin (HCG) levels in your body elevate. Your urine also contains HCG, which will enable you to test for pregnancy using an HCG strip at home. Your egg has also been fertilized in the fallopian tube and moves to your uterus. In this entire week, your egg is dividing into hundreds of cells.

Fourth Week of Trimester

In the fourth week of your pregnancy, your egg attaches itself to the inside wall of the uterus. The blood vessels that connect the egg to the lining of the uterus help provide your developing baby with essential nutrients and oxygen. These blood vessels are also connected to the blood vessels of the placenta, which helps flush out waste matter. Your baby is no longer an egg; but has turned into an embryo. It’s beginning to develop its heart and the circulatory system. The baby is also developing its nervous system, spinal cord, skin, and hair. This is the time when your baby is taking its form. In order to ensure that a healthy baby is formed, you need to increase your intake of folic acid, which will keep your baby safe from spina bifida (a birth defect).

Fifth Week of Trimester

As you enter the fifth week of your first trimester, you will begin to feel some prominent physical symptoms. Your breasts and nipples will become tender. You will also feel minor cramps in your stomach, which means that your baby is making its presence more noticeable. The umbilical cord and placenta is also formed, which is feeding your baby the nutrients that you consume. Its brain is also starting to develop and your baby is now 2mm in size, similar to a small bud of flower.

Sixth Week of Trimester

When you enter the sixth week of your first trimester, your baby increases in size and measures 4-5mm. This little baby also has four tiny buds, which will soon take the form of arms and legs. This is the time when your baby’s eyes begin to develop. It is also developing lungs, kidneys, and intestines.

Development of your baby in the First Trimester

Seventh Week of Trimester

This is the week when your baby has grown arms and legs, but is yet to develop knees and elbows. Its lungs and lenses are formed, and it has tiny ridges at the end of its hands and feet, which are its fingers. This is the time when your baby’s facial features start to develop.

Eighth Week of Trimester

In the eighth week of your pregnancy, your baby’s growth speeds up and its organs begin to function properly. It is also developing its knees and elbows, which means that you will soon be experiencing its mischief. Bones and cartilage are also starting to develop, and your baby is now regarded as a fetus.

Ninth Week of Trimester

In the ninth week, your baby is taking shape of a tiny human. Its nose, eyes, ears, bones, and muscles are visible under its translucent skin. This is the time that your baby being sot make slight movements, but you will not yet feel them. 

Tenth Week of Trimester

Your baby’s fingers, nails, hair, and feet are developed and it starts to make small movements inside your womb. During the tenth week, your baby’s nervous and digestive system further develops, and its eye color is also determined. Its eyelids are still covered with a thin layer of skin, which means that it is still unable to see.

Eleventh Week of Trimester

Your baby is becoming more human-like at this point and has begun to pass urine through its kidneys. Its fingers and toes are separated, and it has started to make voluntary movements. This is the time when your baby starts to kick you and make its presence count. It has also started to suck and swallow the amniotic fluid.

Twelfth Week of Trimester

In this week, your baby’s soft bones are beginning to harden. This is the week that your baby’s sex organs are formed, and its eyes and ears are in correct place. Your baby also starts to experiment with its toes and hands at this time.

Thirteenth Week of Trimester

The last of the first trimester is coming to an end and your baby is developing more organs. The minor details like fingerprints are starting to develop and it is now producing bone marrow. The foundations of your baby’s body is now perfectly formed, and all is left is maturity and body growth.

When the first trimester of your pregnancy is over, you can finally take a sigh of relief as your baby has now entered into a safe stage. Your baby continues to develop and increase in size, which is evident in the size of your belly bump. You also begin to feel much relaxed, and your skin starts to glow. So, enjoy your second trimester and give the best care to your baby.

© Teresa Boardman, Nanny Options.


Browse other Parenting Guide articles from Nanny Options
or keep up to date with us on Facebook.

Avatar
Nanny Optionshttps://nannyoptions.ie
Nanny Options is an International Irish Childcare Agency based in Dublin. We provide Experienced and Professional Nannies, Maternity Nurses, Babysitters, Special Events Nannies, Housekeepers, Tutors, Sleep Training, Parenting Classes and First Aid Courses. Our Director, Teresa Boardman who has 30+ years’ knowledge is committed to providing you and your family with a quality service. She has gained a broad experience of children within different family setups.

Related Posts

Stay Connected

4,496FansLike
0FollowersFollow
321FollowersFollow

Parenting Guide Articles

How often should I bathe my baby

It is up to you how often you bathe your baby. Some babies love being in the water, and giving your baby a warm...

Joining Two Families Together

Joining Two Families Together Combining two families together into a new unit is not an easy task. Making a new family means new rules, new...

Autism

Autism Autism is a part of the developmental disabilities group known as Autism Spectrum Disorders. It’s a children’s disorder and each child is affected differently....

Health Centres

A list of Dublin based Health Centres, please feel free to print it out and keep it in a safe place. Health Centres – North...

Bathing and Equipment

For the first few weeks your baby may not enjoy bath time. This feeling will pass quite quickly and when they start feeling more...

First Aid Courses

Nanny Payroll

Member Of