4 to 8 weeks
I am now an embryo
At around 6 weeks my genitals start to grow

My heart is already pumping blood around my tiny body
My spinal cord and brain are already forming and there are small stumps where my arms and legs will grow

9 to 12 weeks
All of my major organs are busy growing, including my sex organs, although you can’t tell whether I’m a boy or a girl by looking yet.
The soft cartilage in my body is beginning to be replaced by bone, and the teeth in my gums are developing ready for I will need them
By the end of week 12 my kidneys have developed enough to start making urine  
At your ultrasound you might be able to see where my eyes, nose and mouth are growing.
12 Weeks marks the end of the first trimester – risk of miscarriage reduces greatly after this point and

13 to 16 weeks
My bones are growing stronger now
You may be able to see whether I am a boy or a girl on a scan now

17 to 20 weeks
My body is covered in a thick fatty waxy substance called vernix to protect my skin
I am covered in silky hair, called lanugo, which *
My limbs are almost

21 to 24 weeks

25 to 28 weeks

28 to 32 weeks

32 to 36 weeks

36 weeks to 10weeks

Johnson, M. (2014) Human Biology 7th Edition   Essex; Pearson Education LTD
Marieb, E. (2012) Essentials of Human Anatomy and Physiology 10th Edition   USA; Pearson Education Inc.