Foetal developement

Rob Pettit
Mind Map by Rob Pettit, updated more than 1 year ago
Rob Pettit
Created by Rob Pettit over 6 years ago


Stages of development of the fetus in the womb

Resource summary

Foetal developement
  1. First trimester
    1. Weeks 1-6
      1. Weeks 7-8
        1. Now about the size of a kidney bean, the head is taking shape. Organs are all in place and limbs are forming. Inner ears are starting to function. Soft cartilage is beginning to turn to bone. The tube that connects the spine and brain, called the 'neural tube', closes up. The baby is called a 'foetus' rather than an embryo.
          1. Weeks 9-10
            1. Now about 22mm long. Major organs, fingers and toes continue forming. The face is starting to form and a mouth and tongue. Jawbones already have tiny tooth buds. Fingernails start to form. Hiccups occur.
              1. Weeks 11-12
                1. Around the size of a plum, baby will be fully formed with all the organs, bones and muscles in place. The placenta will be fully developed. Toe/fingernails are forming. Can feel pain, suck thumb and grasp. Vocal chords are formed. Moving more, can swallow and 'breaths' amniotic fluid.
            2. The embryo is the size of an orange pip and implants in the uteras. Layers of cells develop that will become different parts the body. Some cells will turn into the placenta. Before the placenta has formed, the embryo gets energy from a ‘yolk sac’. The amniotic fluid starts to form in the sac that surrounds the embroyo. The heart is beating with babies own blood (often different to mothers). The brain, spine and nervous system start to develop. Four 'buds' start to form that will become the arms and legs. Tiny dents in the head will develop into the eyes, ears, mouth and nostrils.
          2. Second trimester
            1. 13-14 weeks
              1. About the size of a kiwi fruit (25g / 85mm long), the genitals are forming although is unlikely to reveal the sex. A heartbeat can be heard with a foetal heart rate monitor held to mothers stomach.
                1. 15-16 weeks
                  1. Around the size of a lemon, baby is covered in fine hair called lanugo. The kidneys start working, passing urine which goes into the amniotic fluid.
                    1. 17-18 weeks
                      1. Baby will now weigh around 150g. The placenta continues to grow. The head was bigger in proportion to the body, but now proportions are evening out. Eyebrows/lashes are starting to grow, eyes can move, eyelids are still shut.
                        1. 19-20 weeks
                          1. 21-22 weeks
                            1. Baby is growing hair. Outside sounds can be heard, including voices. Taste buds will continue to develop, and practising swallowing in readiness for life outside the womb will occur. The lungs are not yet ready for life outside the womb. All oxygen is received from mothers blood via the placenta until he takes his first breath after he’s born.
                              1. 23-24 weeks
                                1. Baby is said to be ‘viable’. This means that there is a chance that she would survive if she was born now. Baby is getting into a pattern of sleeping and waking.
                                  1. 25-26 weeks
                                    1. About the length of a forearm, eyelids open at around 26 weeks and eye colour is very likely to be blue. Baby will hiccup and respond to sounds. The lungs are still not fully mature.
                                      1. 27-28 weeks
                                        1. Baby will be having periods of sleep and periods of activity, which can be detected by movements in a regular pattern. If the pattern stops or slows down it should be checked immediately.
                                  2. Around the length of an A4 piece of paper, the baby is gaining weight but doesn’t have much fat on its body. Mother starts to feel proding or kicking. By week 20, baby’s skin is coated in a white, creamy substance called vernix. This is thought to protect babys skin while in the womb.
                          2. Third trimester
                            1. Weeks 29-30
                              1. Baby will measure around 33cm from head to toe. The eyes can open and light detected outside the womb. As well as being able to open his eyes, he can turn towards light . More fat under the skin reduces wrinkles and the skin is smoothing out.
                                1. Weeks 31-32
                                  1. The womb tightens every so often, in readiness for the birth. This is called Braxton Hicks contractions. Fingernails are growing and baby will have its own pattern of movements. Babies do not slow down at the end of pregnancy, it can be a sign baby is having problems.
                                    1. Weeks 33-34
                                      1. The brain and nervous system are now fully developed. Baby turns around and is head down deep into the pelvis. This is called ‘engaging’.
                                        1. Weeks 35-36
                                          1. If baby was born now it would have a very good chance of survival. The lungs are ready to breathe and baby would be able to suckle. Baby is still laying down extra layers of fat to help regulate temperature after birth.
                                            1. 37-38 weeks
                                              1. Full-term, baby will probably move head-down into the pelvis ready to be born.
                                                1. 39-40 weeks
                                                  1. Ready to be born. Most babies are delivered between 38 and 42 weeks of pregnancy. Movements do not slow down in late pregnancy.
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