Pregnancy Week 1 – The Baby’s Progress

In pregnancy week 1, although you won’t yet know that you are pregnant, the building blocks of your baby’s design have already been programmed in. As soon as your egg meets the strongest cohort of sperm it will then penetrate the oocyte (the innermost part of the egg) and shed it’s tail to be left outside to naturally disintegrate. The two will form one single cell called a zygote which will develop a thick wall around itself to prevent any further penetration from other sperm….



Within 24 hours the zygote will then begin to divide into further cells called blastomeres as it travels down along your fallopian tubes. It takes up to 72 hours for this little ball of cells to arrive at your uterus by which time the maturing cell life is referred to as a blastocyst. About 1 week after the initial fertilization took place the blastocyst will finally and securely embed itself into the lining of your uterus by growing little finger-like tentricles.

It will then announce its arrival to your body by secreting the hCG (Human Chorionic Gonadotrophin) hormone which signals the body to continue producing another hormone called progesterone. These hormones will then trigger off a chain reaction which will prevent the break-down of your uterus lining thereby stalling your next menstrual cycle. An immunosuppressant protein will also be released into the body in pregnancy week 1 to prevent your own immune system from mistaking the blastocyst as a foreign body and attacking it. In these pregnancy first weeks it will enable the embryo to continue and remain viable.

Now safe in it’s arrival the blastocyst will continue on with its cell division with each cell given it’s own function that cannot be changed. Within a few days it will develop into an embryo. By the time you enter into the second week the embryo will already have 3 seperate cell layers on it’s body known as ‘germ layers’ that will define different parts of your baby’s body even though, amazingly, it’s still not big enough to be visible to the naked eye.

Although you may not have experienced the earliest possible signs of pregnancy yet, your uterine walls will already begin to soften and the lining of your cervix will thicken. In pregnancy week one it would not be possible to determine an accurate pregnancy reading yet. Home pregnancy kits will confirm a positive reading by detecting the hCG hormone in your urine and the levels will not be high enough to read until the end of the second week.

Week 2 >>

(See 1 Week Pregnant – The Mother’s Progress)


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