Pregnancy Week 8 – The Baby’s Progress

Pregnancy week 8 marks the start of ossification. The cartilage that was laid down a couple of weeks ago is now going to begin receiving calcium in order for it to harden into bone. The first bones to ossify are the leg and collar bones, along with the spine, therefore lifting the head and straightening the torso. These bones will continue developing up until your child reaches adolescence. Calcium distribution will also mark the start of hair and nail growth.

Pregnancy Week 8 What To Expect – Ossification  Begins

Although still very small, the head is characteristically human looking now as the scalp is complete and cylindrical. As the head and torso increase in size over the coming weeks, the eyes will begin to migrate forward from the sides of the head and the ears will establish their final position higher up on the head. The tongue is now present and the eyelids are almost complete, ready for fusing together.

The diaphragm that separates the chest cavity from the abdomen is now forming, along with the larynx and trachea. Mammary glands are continuing to mature and an airway passage is opening in the respiratory tract. The liver will also begin it’s early stages of development this week.

Germ cells have began responding to genetic signalling and the genitalia of the male and female embryo’s have begun to form. The critical heart development phase has now ended and will just continue to grow and mature with the heartbeat getting stronger, along with the body’s muscles. Anal membrane now appears and becomes perforated as the tail is almost completely gone.

Although your 8 week fetus is clearly moving now, you are not likely to become aware of their physical presence until around weeks 18-20 if you are a ‘first time’ mother and possibly as early as week 16 if this is your second or third child. It usually happens once the lower limbs are fully grown and in proportion. The lower limbs normally develop slower than the arms hence the reason a child can grab and pull at things before they are able to walk. So at this stage the toes are still webbed but the fingers are beginning to separate and lengthen and the arms are now bending at the elbows.

Your baby’s skin is still transparent during pregnancy week 8 and absorbing nutrients from the amniotic fluid. This absorption will take place until her kidneys begin to function and she has learnt to swallow, then the amniotic fluid will be taken orally and secreted it back into the amniotic sac. The main source of nutrients, however, will come from the placenta from week 12 onwards.

Finally, by the end of pregnancy week 8, the upper lip will be fully formed and the cleft palate will seal closed, if this process is not complete it will lead to a condition known as ‘cleft lip or cleft palate’. All the major critical organ developments are now complete, so this marks the end of the ’embryonic phase’ and you are now legally recognized as carrying a fetus (a Latin word meaning ‘young one’ or ‘little one’).

By the end of this week, your 8 week fetus will measure approximately 0.79” (20 mm) crown to rump.

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(See 8 Weeks Pregnant – The Mother’s Progress)


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