fetal growth and development

Fetal Growth and Development

Stages of Fetal Development – Pregnancy Timeline


After the egg and the sperm have united, the tiny bundle of cells begins to divide and multiply rapidly. Three weeks following conception, these cells have formed into an embryo and the tiny human being begins to develop a central nervous system and brain.


Up to Week 8 of Pregnancy


By now internal body organs are starting to form. This is the first time the foetus (or more correctly at this point – the embryo) inside begins to look something like a human being, although it is probably fair to say it looks more like a jelly baby at this stage of its development! But it has the beginnings of limbs, ears, eyes and heart. The heart actually starts to beat from around about five weeks following conception, but roundabout week 8, it’s going at approximately 150 beats per minute. In the brain of the fetus, an unbelievable amount of growth takes place as cells are produced by the million every single minute. The part of the brain that is responsible for reflexes and body movement, the brain stem, begins to take shape.


fetal growth and development

Up to Week 12 of Pregnancy


By this stage the baby is referred to as a fetus (or foetus).  If one were to look at fetal fotos at this stage of development, you could see that it possesses arms and legs, feet and hands, even fingernails. It can now move inside the womb and the mouth and throat begin to function as the baby learns to move its lips and mouth muscles. All the organs are functional including the lungs. Amazingly, the baby actually breathes in amniotic fluid and then expels it again. There is a thin layer of hair over the whole body also.


In the brain of the fetus more and more neurones are produced and begin forming an interconnected structure that will eventually control all the reflexive and non reflexive movements such as blood flow, breathing, eating, drinking, and swallowing etc. Remember, the baby is learning already, even before birth! It also responds to the mother’s hormonal and psychological state. When the mother is experiencing highs and lows, corresponding indicators in the baby can also been monitored using 3d or 4d ultrasound pictures.


Up to week 16 of pregnancy


By this point in fetal growth and development, the eyes and ears start maturing at a greater rate now as the baby can pick up vibrations inside the womb coming from noises outside. Even though her eyes are shut tight due to the eyelids being fused, the baby can sense light conditions in the external environment. The baby develops tastebuds and a keen sense of smell, and practices sucking her own thumbs in preparation for breastfeeding later on.


Sexual organs have already formed by this stage. If it is a baby girl she already possesses ovaries which even at this stage contain up to three million eggs! Tiny teeth are beginning to appear. Vocal cords begin to develop. Even though the baby is probably only 6 inches long at this point, the hands have a full set of fingerprints.


During this phase of fetal growth and development the brain goes into overdrive producing almost 600,000 new neurones every minute. Thalamus and cortex join which now means that your baby can experience discomfort, sadness, happiness and physical pleasure.


Up to week 22 of pregnancy


This is the earliest point that the developing fetus could survive if born. The skeleton begins to harden off and the skin becomes more mature, capable of sensing touch everywhere except the head. Luckily for the baby, the nerves in this area are temporarily deactivated to lessen the pain that could potentially be experienced during birth.


At this point in time, the growing fetus instinctively starts to reach around the womb feeling for something to grab such as the umbilical cord.  By now the brain of the fetus is developed to such an extent that the baby can even experience dreams. Untold millions of neurones are now interconnected. The child is fully capable of experiencing and forming memories related to her environment.


Up to week 28 of pregnancy


Some of the nutrition the baby now gains from the mother, is being stored as fat, which will sustain her during the rigours of birth and a few days prior to starting breast feeding. The baby’s eyelids are now mobile and she practises opening and closing them. The baby becomes ever more focused on the external environment now. She responds to noises from the outside with increased heart rate and also reacts to you touching your abdomen.


The brain of the developing fetus now has over 100 billion neurones and is now set to facilitate a lifetime of learning. Putting any processor in your personal computer to shame, the brain processes over one million chemical reactions every single second. Portions of the fetus’s brain assigned to talking and listening continue to mature as does the ability to react emotionally and store memories.


Up to week 32 of pregnancy


Even now, prior to birth, a baby expands much energy on developing its own ability to one day produce offspring itself. At this stage of fetal growth and development a female baby’s labia are developing, as are the boys testicles which slowly migrate from the kidney area down to the scrotum. Sleep cycles are now in place to some extent, and like anybody else, the baby can be awakened by disturbances such as noise and bright lights, and motion from the mother. It is thought that the baby even has the capacity to appreciate music and become familiar with particular songs and melodies.  The brain begins to expand rapidly now and the head elongates. Brain activity is increased and the baby evening experiences rapid eye movement dream sleep R.E.M. As the baby develops more more memory and experiences of stimulation from within and outside the womb many more connections are made between the billions of neurones.


The final weeks before birth


Body weight increases rapidly now. Over 30 per cent of the baby’s total weight is gained during the two months prior to birth. Everything continues to develop such as the organs, fingernails, hair and arms and legs. The skeleton hardens even more with the exception of the skull. This remains rubbery and pliable. The separate bones of the skull are capable of sliding over each other and this enables the baby to exit the womb easier.


The very fine body hair, known as Lanugo, has now shed into the amniotic fluid and actually been eaten by the baby! The lungs are now preparing for the transition from an aquatic environment to air. A liquid known as surfactant is produced which decreases the surface tension within the respiratory tract. This enables the lungs to fill with air after birth so that the newborn can take its first breath.


The head and the brain outpace growth in the rest of the body as even more neurones connect. It is from the brain of the child that messages are sent which promote the release of hormones that interact with placental hormones. These are responsible for the onset of contractions.


During Labour


Some babies are much busier than others during this stage of fetal growth and development. The lazy ones just take it easy and let the mother to most of the work! Others twist and turn vigorously down the birth canal which assists the mother in her efforts. The head of the baby is bigger than the gap it has to exit through – the vagina.


This problem is solved as the head is capable of great flexibility due to the previously mention rubbery nature of the bones in the skull. The baby’s scalp pushes on the cervix with each contraction and its head become smaller. The combination of fully dilated cervix, and flexible head is what enables the rest of the body to pass through the vagina into daylight.


Babies manage to sleep for certain periods during labour but they do wake up when they sense that contractions are near. The powerful forces of contraction also prepare the baby’s mind and body for birth. Most babies go through labour without any upsets. However, monitoring of baby’s heart rates and brain patterns during births, has revealed that some do feel pain and anxiety at this time. This discomfort is usually increased, and understandably so, with births involving instrumental deliveries.