Fetal development

Life begins with a new conception, 23 + 23 = 46 chromosomes

Cleavage, mitosis cell division

Implantation of the early embryo or blastocyst occurs at about 7 days, a few hundred cells

Development at 4 Weeks

All tissues are present, connective, epithelial, neural tube which will become CNS

Developing the structures that will form face and neck.

The heart and blood vessels continue to develop.

Lungs, stomach, and liver start to develop.

A home pregnancy test would show positive.

Slide 4, 5th week post ovulation

An opened oviduct with an ectopic pregnancy

Anatomic features, including tail, limb buds, heart (which actually protrudes from the chest), eye cups, cornea/lens, brain,

Blood cells now being produced

Cardiac contractions began at 3 weeks

Neural tube is closed

8 weeks

Final week of the embryonic period

Organogenesis in now complete

Fetal period begins start of week 9

Eyelids and ears are forming, and you can see the tip of the nose. The arms and legs are well formed.

The fingers and toes grow longer and more distinct.

External genitals differentiate

Heart has 4 contracting chambers

Umbilical cord has one vein and two arteries

Development at 12 Weeks

Starts to make its own spontaneous movements. Top of the uterus can be felt above pubic bone.

Elbows and knees have been bending since week 10

Heart beat may be heard on examination

The sex organs of should start to become clear

Development at 16 Weeks

Mum can feel the top of the uterus about 3 inches below your belly button.

The baby’s eyes can blink and the heart and blood vessels are fully formed.

The baby’s fingers and toes have fingerprints.

Development at 20 Weeks

Between 17 and 20 weeks gestation, thalamo-cortical relays penetrate the cortex.

20 weeks gestation, pain receptors are present and linked.

By 20 weeks gestation, the baby will respond to sound and move, wince, and recoil from sharp objects and incisions.

Big stress hormone response since 18 weeks

Uterus the level of the belly button.

The baby can suck a thumb, yawn, stretch, and make faces.


Slide 14, 24 weeks

Baby now and responds to sounds by moving or increasing their pulse.

Mum may notice jerking motions if they hiccup.

With the inner ear fully developed, the baby may be able to sense being upside down in the womb.

Slide 15, Development at 28 Weeks

Sleeps most of the time, clear sleep wake cycle by about 30 weeks

Activity rapid eye movement sleep

and the quiet resting state of non-REM sleep.

Baby’s First Dreams: Sleep Cycles Of The Fetus

Evidence for early dreaming

Slide 16, Development at 36 Weeks

The brain has been developing rapidly.

Lungs are nearly fully developed.

The head is usually positioned down into the pelvis by now.

Early term baby if born between 37-39 weeks

Term, born at 39-40 weeks

Late term 41-42 weeks

Written by Dr. John Campbell

Hello Everyone,My name is John Campbell and I am a retired Nurse Teacher and A and E nurse based in England. I also do some teaching in Asia and Africa when time permits. These videos are to help students to learn the background to all forms of health care. My PhD focused on the development of open learning resources for nurses nationally and internationally.


Leave a Reply
  1. Thank you Dr. Campbell for such a scientific and yet compassionately delivered video on the miracle of life! I never tire of seeing how wonderfully made we are from conception onward. Psalm 139 expresses how King David felt about it! It’s a marvel that all humans should appreciate. 28 years ago my little girl died in the womb at 24 weeks due to a defect that occurred during those very first stages of cell division you mentioned… a condition termed Turner’s Syndrome. She could only develop so far with organs not completely developing as they normally would have causing interrelated complications . But after inducing labor I was able to hold her and see her beautiful face and little body that I will always cherish.

  2. There should be no doubt that ‘human life’ begins at conception. And termination of that life should never be undertaken lightly. For too many people, it’s like ‘just do it’ and forget about it. Don’t for heaven’s sake picture the process. Or think about that little being. Not unlike what we meat eaters do when we take the lives, often inflicting pain, on fully grown sentient animals who just want to live…..

  3. Very interesting. I can see that you are passionate about this topic and many others. I wonder if you realise how biased that actually was, with respect to the debate you are not willing to enter into.
    Just look at the first sentence… "Life begins with a new conception, 23 + 23 = 46 chromosomes". Who says when life begins? Who defines what we mean by life?

  4. I was at the mountain I love to hike and I encountered snakes – I thought 💭 “ if I die here, then it was my fate. I decided to come. I came unprepared. It was all on me. My choices have consequences because I don’t have control of nature. I can only chose to be prepared🏡. “. Now, if I recklessly start playing with the snake and hoping it won’t harm me at all because I am in control then I should not complain about the possibility of being harmed to death, right? So having sex is a choice which comes with consequences. Even if there are women who have pregnancies which are sad, no one gives the right of one person to kill another. It was her choice to have unprotected sex and even if it was protected, the fact that something fatal can always happen is part of being human or a woman. Nothing ever will exonerate murder of convenience

  5. I was unsettled by the fact that you spoke of weeks from fertilisation for the early weeks and then weeks of gestation for the later weeks. I admire your work and I know you are very intelligent. Was this in any way a manipulative tactic? You usually pay such close attention to detail and specifics. And you usually go out of your way to explain details that could give people an inaccurate belief, which is what leads me to wonder if you were purposely trying to give your viewers a distorted sense of how soon early development takes place.

  6. We learned this at school, but that was around 35 years ago, but it was nowhere near as detailed as this.

    When i was young i thought that the fetus was quit small and very nonhuman like, within the period where you were allowed to do an abortion (if you didnt want it due to bad timing in life / it was "propery sick/misformed" / it was totally a unwanted pregancy etc).

    I then watched this and that really was an eyeopener: Warning: grim stuff.
    **poor doctors (or even nurses) that has to do such a job (and on a daily basis, even)**.

  7. To abort a baby is an awful thing.
    To force a child of 11 or 12 who has been raped to carry a baby in her immature body and look after it afterwards is also a dreadful thing.
    To allow a woman to die because a foetus is decaying in her body is cruel .
    Some decisions are heartbreakingly difficult.
    It isnt just about abortion on demand
    It should be a case by case decision

  8. Thank you for this video! I truly think that this type of content can go some way towards healing the deep divides in our society; purely scientific, objective facts without the toxic political rhetoric, yet still defending life from the moment of conception. I am so fascinated by embryology and the incredible processes of fertilisation, pregnancy and birth and the photos were amazing, even if sad ❤💔

  9. "I'm not going to get involved in that debate." Now let's talk about the the vassal that makes this process of creating life possible. Does her autonomy halt with a zygote? Just asking.

Leave a Reply

Your email address will not be published.