Guide To Fetal Developmental Stages

Guide To Fetal Developmental Stages

Guide To Fetal Developmental Stages

Congratulations on your pregnancy! Here are the development stages your little one will go through over the next 9 months: 

First Trimester

The first 12 weeks after conception make up the first trimester. Over this time, the fertilized egg will change from a cluster of cells to a fetus that starts to develop baby features.

Month 1 (Wk 1-4) 

After fertilization, a water-tight sac forms around the egg, known as the amniotic sac. The amniotic sac cushions the growing embryo. 

The placenta also starts developing during this period. It is the organ responsible for transferring nutrients from the mother’s bloodstream to the developing embryo and also waste from the embryo and out of the body. 

By the end of week 4, the embryo will have started developing into separate sections that will form the head, abdomen, chest, and organs. There will also be small buds on the surface that will form into legs and arms.  

Month 2 (Wk 5-8)

Over this period, the embryo will develop a tiny mouth, nose, and ears. Eyelids will also form but will stay shut until later on. Other organs such as the lungs, heart, neural tube (spinal cord, brain, and other neural tissue of the central nervous system), digestive tract, and sensory organs will also start developing, 

After week 8, the embryo will start being called a fetus.

Month 3 (Wk 9-12)

The hands, fingers, arms, feet, and toes are fully formed at this stage. The fetus can also open and close its mouth and fists. The earlobes will also form as well as the fingernails and toenails.

By the end of month 3, the fetus is fully formed. All the limbs and organs are present and developing to allow for functionality. 

The reproductive organs will also start to develop but it will still be difficult to determine the baby’s gender on ultrasound. 

Second Trimester

By the second trimester, most discomforts associated with the first trimester are gone. This is also when you can find out your baby’s gender!

Month 4 (Wk 13-16)

Your baby can move its facial features to make random expressions. Nails, hair, eyebrows, and eyelashes are formed. Bones and teeth are becoming denser. Yawning, stretching, and sucking the thumb are common. 

The nervous system is also functional and the reproductive organs and genitalia are fully developed. This means your doctor can identify the baby’s gender during an ultrasound scan. 

Month 5 (Wk 17-20)

Your baby’s movements will start becoming more noticeable. As the fetus’s muscles continue to develop, you’ll notice that those flutters and kicks from their movements get progressively stronger, and you can start picking out patterns of their movement. 

Month 6 (Wk 21-24) 

By the sixth month of pregnancy, you will start noticing that your baby can now move in response to external stimuli such as loud sounds outside your belly. You may also notice jerking motions if your little one hiccups.

Month 7 (Wk 25-28)

At this point of pregnancy, your little one’s hearing is fully developed. The fetus also develops reserves of fat, which means his/her skin gets smoother as he/she gains weight. 

Responses to external stimuli also become more pronounced at this stage. Your little one can now respond to different stimuli, including light, sound, and pain. 

Third Trimester

This is the last stage of pregnancy. Typically, full-term pregnancy is 40 weeks, although there are cases where women go past their due dates by a week or two (41 or 42 weeks). Keep in mind that if you go past the due date and fail to go into spontaneous labor, you may have to be induced.

Month 8 (Wk 29-32) 

Your little one continues to grow and develop reserves of body fat. Kicks and flutters may intensify in this month. The brain is rapidly developing, and the fetus can hear and see. Most internal systems should be fully developed, but the lungs may still be underdeveloped.

Month 9 (Wk 33-36) 

At month 9, the lungs are almost fully formed and the fetus can respond to light, sounds, and touch. They can blink, turn the head, close their eyes, and grasp firmly.

Month 10 (Wk 37-40)

This is the final month, which means you could go into labor at any time. Your baby won’t be moving around as much as before because space is limited. They will have positioned themselves headfirst towards the birth canal in preparation for birth.

Final Thoughts

Knowing the various developmental milestones that your baby is going through in your womb is delightful and reassuring. Plus, it builds up the anticipation for your little one even more! 

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