The growth and developmentstages of the baby from conception to birthThe human reproductive system contains all the organsneeded for reproduction and producing babies. Conception occurs in thefallopian tube when male sperm meets the female egg and fertilizes it, andbegins to develop into fetus and finally a baby. During this process woman’sbody will undergo many different changes. The development stages of pregnancyare called trimesters, or three-month period, because different changes occurat each stage. During each stage of development, different physical changestakes place in fetus and the baby will develop very quickly in the 40 weeks ofpregnancy.
0-4 weeks:Weeks of pregnancy are dated from the first day ofthe last period. This means that during the first two weeks you are notseverely pregnant, your body will be preparing for ovulation. The mostimportant time for intercourse is the two days before and the day of ovulation.The fertilization of the egg begins when a sperm penetrates the female egg.When sperm fertilizes a woman’s egg it becomes a zygote and during this periodthe zygote will move down the fallopian tube to the uterus where it willcontinue to grow and attach to the blood-rich lining of the womb. Safe insidethe uterus it changes again. A cavity forms its center, and two groups of cellsare formed.
One group of cells become embryo and the other will becomeplacenta. In these first weeks of pregnancy, the embryo is attached to a smallyolk sac that provides food. A few weeks later, the placenta will be fullyformed and will take over the nutrient transfer to the embryo. Hormones fromthe embryo now flow through blood stream; a blood test taken at now wouldlikely detect the pregnancy. 4-8 weeks:During this time baby’s major organs are developingrapidly and he or she is changing from embryo to fetus. Until eight weeks afterconception the developing baby is called embryo, from eight weeks until birth,the developing baby is called fetus. At four to five weeks the embryo is thesize of a pea and during this early stage the embryonic cells are divided intothree layers: · TheEctoderm- forms the outer layer of the baby, the skin, nails and hair, it foldsinwards to form the nervous system (brain, backbone and spinal cord)· Theendoderm- forms all the organs inside the baby. · Themesoderm- develops into the heart, muscles, blood and bones.
After six weeks the embryo is about the size of alentil and has a heart, which beats up to, 150 per minute and arms and legsappear as buds growing out from the embryo. By week seven the baby will be thesize of a small bean, arms and legs and even fingers will be forming. At thispoint the head of the baby is far bigger than other parts and small sectionsbegin to be visible eyes, nose and ears. By week eight the baby will have moredeveloped brain and heart, and the arms will be long enough to bend and tinylegs may meet in front of the baby.
8-12 weeks:At eight to nine weeks the unborn baby is calledfetus and measures about 2cm long, by this time baby’s face will start forming.Toes and finger start to form and the major internal organs such as heart,brain, lungs, kidneys and gut, continue developing rapidly. By week 10 smallthings start to form on the fetus including fingernails and hair, ears start todevelop on the sides of the baby’s head and the ear canals are formed insidethe head and also jawbones start developing, already contain the future milkteeth.
By the week 11-12 babies can move fingers and toes and fingerprintsformed. The baby starts smiling, sucks, swallows and urinates. The sex of thebaby can be said at this time.
12-16 weeks: At 12-16weeks the fetus has grown fully and is now around 10cm long and weighs about100g. By 12 weeks the unborn baby is fully formed and just need to grow anddevelop. By week 13 babies ovaries or testicles are fully formed and their genitalscan be formed outside the body. By week 14 babies begins to swallow little bitsof amniotic fluid which passes into the stomach and kidneys start functioning.Around week 15 babies start to hear from outside the world and any noisesdigestive system makes. They also start becoming sensitive to the light. Byweek 16 muscles of the baby’s face can move and have a fully workingcirculatory system and urinary tract. 16-20 weeks:At these weeks the fetus is large enough for themother to feel its movements.
By the 17th week of pregnancy, the baby grows rapidlyand weighs around 150g. The baby’s eyes now move although the eyelids are stillclosed and the mouth can open and close. The baby moves a little and reacts tothe loud sounds from the outside world, such as music. The week 20 reproductiveorgans and genitalia are now fully formed and may able to know the sex of thebaby by ultrasound.
At this point in pregnancy the baby’s skin is covered in awhite greasy protective film called vernix. This will protect the skin of thebaby for a long period of time in the amniotic fluid and will also help duringbirth. 20-24 weeks:By 20 weeks the baby weighs around 350g, at this timethe baby becomes covered in a very fine, soft hair called lanugo. It keeps thebaby in the right temperature and usually disappears before birth. The babystarts responding to sounds by moving or increasing the pulse and may noticejerk motions if baby hiccups. The lungs still cannot function properly, but thebaby is practicing breathing movements to prepare for life outside the womb.The baby gets all its oxygen from the mother via the placenta and will do sountil it’s born.
In the 24th week pregnancy the baby has a chance of survivalif he or she is born. Longevity babies cannot survive because of the lungs andother vital organs aren’t developed enough. 24-28 weeks:During these weeks the baby will be around 14 incheslong and weighs around 900g. The baby moves heavily and responds to touch andsound. A very loud noise may make the baby jump or kick, and the mother willable to feel it. By the time the baby is 24-28 weeks he or she starts urinatinginto the amniotic fluid. The baby’s eyelids are opened for the first time andwill soon start blinking. By week 28 the baby is active and initial breathingmovement begins, and heartbeat falls to 140 per minute and can be heard with thehelp of a stethoscope.
By 28 weeks baby weighs around 1 kg and is perfectlyformed. 28-32 weeks:From 28 weeks the fetus is said to be viable- that isif born now, the baby has a good chance of surviving, although the babies havesurvived from as early as 23 weeks. The baby will be around 15 inches long andweighs around 1.5 kg. The baby grows plumper, and the skin begins to look lesswrinkled and much smoother. The white, greasy vernix and the soft, furry lanugothat covered the baby’s skin for some time begin to disappear.
The lungs anddigestive system will be functioning and fully developed. The lungs aredeveloping rapidly but the baby wouldn’t be able to breath on its own untilabout 36 weeks. 32-36 weeks:In this weeks baby may be around 18 inches and weighsaround 2-2.
5kg. The baby will continue to mature and develop reserves of bodyfat. Baby’s brain is developing rapidly at this time, and the baby can see andhear. The most internal systems are well developed but the lungs may still beimmature. By week 32, the baby lays their head downwards i.e.
. ready for birth.This is known as cephalic presentation. Movements of the baby will be atmaximum and kicks and squirms will be felt and organs will continue to mature.
By 36 weeks baby’s lungs are fully formed and ready to take their first breathafter birth. 36-40 weeks:By 36-38 weeks the baby is 20 inches long and weighs2.5-3kg. In the last weeks some time before the birth, the baby’s head shouldmove down into the pelvis. The baby will be fully developed.
Have instincts andbe ready for the first day of life. The final stages of pregnancy can beextremely uncomfortable for a woman. We may notice that the baby moves less dueto tight space. Baby’s position changes to prepare itself for labor.