What Is the First Trimester of Pregnancy?

A Week-By-Week Guide To First Trimester

What To Expect In The First Trimester

At our 3D Ultrasound Toronto studio, we take pride in delivering the best images and friendliest environment available. Our clients often inquire about their baby’s development, size, what they do at a certain stage and so on. The first trimester of pregnancy is almost always overlooked, but this is when a lot of rapid development takes place. Read on to learn more!

What Is the First Trimester of Pregnancy

While 3D ultrasound and 4D Ultrasound is an amazing way to see the baby, it might help to know what happens at each stage of the pregnancy so that you can expect those things when entering our studio.

We are pleased to announce a series of articles describing the stages of pregnancy and, hopefully, giving you a better idea about what your baby looks like and likes doing at a certain stage. Visit our gallery to see more images of babies in certain stages of development.

As the first article in the series, here will discuss the first moments of the baby’s journey from embryo to becoming a fully developed human being. While we might keep the description short, it will surely be sweet.

This is the first 1/3 of your pregnancy. It will begin with conception and will last until the 12th week. During this stage, the baby will go through rapid growth processes and a lot of the baby’s body will be forming.

How many weeks is the first trimester of pregnancy?
The first trimester begins on the first day of your last period and lasts until the end of week 12. This means that by the time you know for sure you’re pregnant, you might already be five or six weeks pregnant! A lot happens during these first three months.

Pregnancy Symptoms: What is developed?
-Weeks 1-2: You’re not really pregnant! Your doctor will start your pregnancy from the beginning of your last menstrual cycle, while the actual conception will take place two weeks after your last menstrual cycle. So your baby’s actual age is always 2 weeks behind what your healthcare providers tell you.

-Week 3: This is when fertilization takes place, and the sperm enters the egg. The combo, now called a zygote, moves from the Fallopian tubes into the uterus where the rest of the pregnancy will take place, and begins to divide.

– Week 4: The zygote rapidly divides and is now called a blastocyst, and consists of two parts: the inner one will become the baby, the outer all its attributes like the placenta and amniotic sac, etc.

-Week 5: You’ve now got yourself an embryo! The brain, spinal cord, and heart are starting to develop. There are now three layers, each will give rise to certain organs.

-Week 6: The spinal tube closes, and the first facial features begin to show themselves. This is an important time when the heart starts to beat. Baby’s about 5 mm long, or the size of a small lentil.

-Week 7: Nostrils and other facial features will develop, and the arms and legs will start to be visible. They’re about the size of a chickpea or 10-12 mm.

-Week 8: We can now see the eyes, the upper lip, and nose. The length is about 14 mm.

-Week 9: Baby’s arms grow bones and elbows develop. The length of the baby now is about 20 mm.

-Week 10: Eyelids are shut at this stage to protect the eyes, while the neck starts to develop. The head takes a rounder shape. The baby weighs about 4 grams and is about 30 mm long.

What does the 3D ultrasound look like in the first trimester?
-Week 11: Congratulations! You have reached the fetus stage! The baby’s head is still the biggest part of the length (about half). During this time we can start seeing the external genitalia develop into a penis or clitoris and labia majora. The eyes become separated, while the eyelids fuse shut. Red blood cells begin to form in the liver. The baby weighs around 8 grams and is about 50 mm.

– Week 12: Baby’s face starts to look more like a babyface, and fingernails develop. The length is around 60 mm, while the weight is around 14 grams. It is likely the first time that an ultrasound can be done to see if this is a baby boy or a baby girl, although the accuracy is low and will increase with time (16 weeks is the best time to start determining the gender).

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