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Fetal stage (weeks 9–40)

When the organism is about nine weeks old, the embryo is called a fetus. At this stage, the fetus is about the size of a kidney bean and begins to take on the recognizable form of a human being as the “tail” begins to disappear.

From 9–12 weeks, the sex organs begin to differentiate. At about 16 weeks, the fetus is approximately 4.5 inches long. Fingers and toes are fully developed, and fingerprints are visible. By the time the fetus reaches the sixth month of development (24 weeks), it weighs up to 1.4 pounds. Hearing has developed, so the fetus can respond to sounds. The internal organs, such as the lungs, heart, stomach, and intestines, have formed enough that a fetus born prematurely at this point has a chance to survive outside of the mother’s womb. Throughout the fetal stage the brain continues to grow and develop, nearly doubling in size from weeks 16 to 28. Around 36 weeks, the fetus is almost ready for birth. It weighs about 6 pounds and is about 18.5 inches long, and by week 37 all of the fetus’s organ systems are developed enough that it could survive outside the mother’s uterus without many of the risks associated with premature birth. The fetus continues to gain weight and grow in length until approximately 40 weeks. By then, the fetus has very little room to move around and birth becomes imminent. The progression through the stages is shown in [link] .

The growth of a fetus is shown using nine pictures in different stages of development. For each stage, there is a picture of a fetus which gets progressively larger and more mature. The first stage is labeled “9 weeks; fetal stage begins.” The second stage is labeled “12 weeks; sex organs differentiate.” The third stage is labeled “16 weeks; fingers and toes develop.” The fourth stage is labeled “20 weeks; hearing begins.” The fifth stage is labeled “24 weeks; lungs begin to develop.” The sixth stage is labeled “28 weeks; brain grows rapidly.” The seventh stage is labeled “32 weeks; bones fully develop.” The eighth stage is labeled “36 weeks; muscles fully develop.” The ninth stage is labeled “40 weeks; full-term development.”
During the fetal stage, the baby's brain develops and the body adds size and weight, until the fetus reaches full-term development.

Prenatal influences

During each prenatal stage, genetic and environmental factors can affect development. The developing fetus is completely dependent on the mother for life. It is important that the mother takes good care of herself and receives prenatal care    , which is medical care during pregnancy that monitors the health of both the mother and the fetus ( [link] ). According to the National Institutes of Health ([NIH], 2013), routine prenatal care is important because it can reduce the risk of complications to the mother and fetus during pregnancy. In fact, women who are trying to become pregnant or who may become pregnant should discuss pregnancy planning with their doctor. They may be advised, for example, to take a vitamin containing folic acid, which helps prevent certain birth defects, or to monitor aspects of their diet or exercise routines.

A pregnant woman is lying on a table being examined by a doctor. The doctor's hands are on her belly.
A pregnant woman receives an ultrasound as part of her prenatal care. (credit: United States Agency for International Development)

Recall that when the zygote attaches to the wall of the mother’s uterus, the placenta is formed. The placenta provides nourishment and oxygen to the fetus. Most everything the mother ingests, including food, liquid, and even medication, travels through the placenta to the fetus, hence the common phrase “eating for two.” Anything the mother is exposed to in the environment affects the fetus; if the mother is exposed to something harmful, the child can show life-long effects.

Questions & Answers

when young children speak in short phrases using verbs and nouns,what it is referred to
Simran Reply
how old? generally that's how kids talk isn't it?
Ezra
especially shy ones
Ezra
slang
Emma
what are the social psychology concepts
MICOT Reply
their are about seven main theories... hope someone could help out with main one and their characteristic
Neelkanth
the self concept, social cognition, attribution theory, social influence, group processes, prejudice and discrimination, interpersonal processes, aggression, attitudes and stereotypes.
Deepa
what is different between psychoanalysis, psychopathology?
salma
when do children form oppions
Tasha Reply
they sit in home and play home toys
muhammad
oppions?
Grace
How to know other person
RAGHAV Reply
what is the nature and scope of biopsychology?
Pratibha Reply
working along with neurologists and doctors closely on the field related to brain and nerves
devesh
How can one over come a sleep debt
Andy Reply
how does an algorithm save you time and energy when solving a problem
john Reply
by directing your attention or misdirecting your attention to a particular topic
frederick
can an obsession with blood and Gore be caused by psychological trauma
Dalton Reply
psychological trauma is a bit of a wild card in the case of long term effects. everyone has their own unique experience and I dont see why the example in your question couldn't be a possible manifestation.
Elle
it would be a bigger possibility of this resulting from trauma if this began after you witnessed a violent or gory event. however this often comes from the amount of violence and gore we are exposed to through social media, the news, and fictional material like books, movies and video games.
andrina
how can the bipolar and mood disorder can prevent?
Shana Reply
Control stress. Stress is a major bipolar trigger. ... If you would control stress you will simply feel good ....if you want to know more about this DM @shana mae
KhaLid
That brings us to the next question.. How do we actually control stress in an effective way?
Looney
well for me mindfulness meditation techniques are very much effective for coping with stress ....
KhaLid
please what are the major things I need to know now in psychology,because I'm a new student of psychology.
Godwin
Godwin if it is your begining in this field you should first clear some concepts like what is psychology it's etymology , structuralism,functionalism , behaviourism and many other perspectives .....
KhaLid
first of all are you studying in psychology or working as a psychologist
muhammad
studying Sir
Godwin
Thank you Sir Khalid.
Godwin
Muhammad Akram Both ☺️
KhaLid
Far too often, you can't control stress just like that on your own . And it will affect you On subconscious level . When it comes to meditation it's something to take seriously and best to be taught by professional.
Kira
I know there are many other ways but I found this one at my own Kira Emerala!
KhaLid
Hi friends
RAJABU
it can't be extracted I'll tell u that much
Shawnte
someone who study psychology here need help ? anyone ?
khawla
Can I ask for tips when you have no motivation and can't focus with your studies?
Jhea
For Shana, I'm sorry, I can't answer your concern at the moment, because I'm still studying about the basics of psychology 😬
Daydreaming
do meditation, start learning few pages initially n understand before moving to another topic
mini
play a sport of your choice for half an hour or listen to your fav music, develop your positive outlook towards life
mini
learn to balance work play study
mini
n health
mini
I'm struggling with BPD cptsd major anxiety disorders and going to college for a psychology degree. trying to maintain motivation is difficult. what can I do?
Sarah
I already meditate take my meds use biofeedback and several other things
Sarah
As a student, it is normal to lose motivation during college life but look at the long term goal. What do you want to achieve at the end? Divide it into small achieveable goals. Once you achieve it, focus on 2nd small goal. Last thing, it's okay to ask for help when needed. We are all in a journey.
mehdi
what's your friend's circle
muhammad
khawla saadouni yes how can I help you ?
KhaLid
Sarah you need CBT it will be effective on that what you are experiencing !!
KhaLid
implicit memory are those type of memories which can be written without any unconsciousness
Aayu Reply
m interested in this research...
Arnav
me too plz I am suffering from depression so v forgetful which has ruined my life
Sins
yes plank youth
Shawnte
0rayers poracles a d majik
Shawnte
cuffed truthfullcreatibeclarity
Shawnte
sins saintly do you need any help regarding how to cope up ?
KhaLid
nebieiluvrue
Shawnte
yes
Shawnte
what do you mean by sensory memory
Aayu Reply
sensory memory simply is an automatic response, not under conscious control. It deals with the input from the senses. 
KhaLid
what is the name of a person who introduction the techniques of factors analysis in intelligence
JobJoy Reply
what is associated with the developmental
JobJoy
lifelong spiritual advice
Zach Reply
Can you define spiritual Zach?
Emely
Are teeth part of our minds?
Kamil
who introduced the technique of factor analysis in intelligence
JobJoy Reply
Spearman's (1904)
Stephen
apart from Spearmans 1904 who again
JobJoy
Howard Garner
Komal
what scattered and worn triage has created upon resisting the internal anabalistic instinct to kill and conquer
Shawnte Reply
can anyone please recommend me some good psychology books?
Fareha
Id love to help but i would need to know about you.
Shawnte
Hahahahaha
Zain
Hey, I'm a 2nd year college student doing majors in psychology, i really love to read about different psychological concepts that effect us today's world, it would be great if you could recommend any books, thanks.
Fareha
lol @zain its ok i hope i get some books recommend too now
Fareha
anything related to the today's worlds issues and its factors related to the psychological effects
Fareha
obviously psychological concepts that effect about us today related to that @mujtaba
KhaLid
fareha Fatima have you ever read any book related to emotional intelligence?
KhaLid
@Khalid yes i did a few you can recommend me any book anyways
Fareha
thank you @Mujtaba i just downloaded the pdf.
Fareha
interesting emotional intelligence?
Sheila
interpretation of dreams sigmund frued behaviourism by JB Watson the ego and the Id by Sigmund frued
KhaLid
emotional waring made me mick bravery to even introduce my superiority complex without hiding...
Shawnte
yes especially by Daniel Goleman@sheila Henderson
KhaLid
how do i determine if im schizo because the voices i somtimes hear/feel are real.. it dosnt help my borderline personality disorder
Edward
Edward those types of labels are just words trying to capture the equation of some phenomenal behavioristic traits some have been both cursed and blessed with.
Shawnte
@Fareha erich fromm is very interesting
Mal
@Fareha read about personality by Sigmund Frued, Albert Adler & Eric Fromm..... & read about School of thoughts of Psychology...
Zain
electric field lines never cross why?
Hejab

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Source:  OpenStax, Psychology. OpenStax CNX. Feb 03, 2015 Download for free at https://legacy.cnx.org/content/col11629/1.5
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