Developmental Psychology – Chapter 2 (pp. 43-70) – Prenatal Development and the
Newborn Period
Prenatal Development
Great diferences in how people have thougght abougt prenatal development
4th centugry B.C.: Aristotle Does prenatal life start with new individugal, already
performed, composed of a fugll set of tny parts, or do the many parts of the hugman
body develop in sugccession?
o ugnderlying western thougght for next 15 centugries
o rejecton of preformaton (epigenesis) – the emergence of new strugctugres and
fugnctoning dugring development
example: Beng Beginnings (people in Ivory Coast of West Africa) believe in
reincarnaton of ancestors
o frst weeks afer birth: the ancestors spirit “wrug”, isn´t fuglly commited to an
earthly life (dougble existence), travels back and forth btw. everyday world and
“wruggbe” (“spirit village”)
o afer the ugmbilical stugmp has dropped newborn has emerged from
“wruggbe” and is a person
o these beliefs ugnderlie many aspects of Beng infant-care practces
1. life begins before birth - reincarnaton of ancestor
2. life begins also afer birth – when the individugal has become a person
Concepton
gametes (germ cells) – reprodugctve cells (egg and sperm) that contain only half the genetc
material of all the other cells in the body
gametes are produgced througgh meiosis – cell division in which eggs and sperm receive only
one member from each of the 23 chromosome pairs necessary for reprodugcton
reprodugcton starts with the laugnching of an egg from one of the woman´s ovaries
into the adjoining fallopian tugbe
as the egg moves througgh the tugbe toward the ugterugs, it emits a chemical sugbstance,
a “come-hither” atractng sperm toward it
conception – the ugnion of an egg and a sperm – is possible if sexugal intercougrse takes
place near that tme
jougrney sperm: 6 hougrs, 6-7 inches from the vagina ugp througgh the ugterugs to the egg-
bearing fallopian tugbe
high failugre rate (1 million sperm cells, bugt only 200 approach the egg)
o chance
o seriougs genetc or other defects
as sperm´s head penetrates the ougter membrane of the egg, a chemical reacton
seals the membrane, preventng other sperm from entering
the nugclei of the 2 cells merge within 2 hougrs
zygote – fertliized egg cell
process 9 month (38 weeks/266 days)
, Developmental Process
ugnderlying the transformaton of a zygote into an embryo (-developing organism from 3rd to
8th week) and fetus (-developing organism from 9th week to birth)
1. cell division – mitosis (cell division resugltng in two identcal daugghter cells)
o within 12 hougrs afer fertliizaton izygote divides into 2 equgal parts with a
fugll complement of genetc materiall then into 4, 8, 16, etc. newborn
consistng of trillion cells
2. cell migraton – the movement of newly formed cells away from their point of origin
(e.g. neugrons)
3. cell diferentaton – embryonic stem cells (-embryonic cells, which can develop into
any type of body cell) start to specialiize in strugctugre and fugncton (350 diferent types
of cells)
o key determinants: “switched on”/ expressed cellsl locatonl inital exibility
4. cell death – apoptosis (genetcally programmed cell death)
Hormones are crugcial in prenatal development if androgens are present, male sex organs
develop (sougrce of androgens is the fetugs itself, arougnd the 8th week afer concepton tests
begin to produgce these hormones)
Sex diferences
male bias at birth: more male embryos were conceived than female ones
o male fetugses are more sugsceptble to spontaneougs aborton than females in
the 1st week and last weeks of pregnancy
o male infants are more likely to be born at very low birth weight and are less
likely to sugrvive
stugdy:
o concepton is equgally likely
o female fetugses are less likely to sugrvive early gestaton
o boys are more likely to experience fetal distress dugring labor & delivery
o male infants are more likely to die from sugdden infant death syndrome
o in many societes, both historically and cugrrently, male ofspring are more
highly valuged, and therefore more likely to sugrvive
Early Development
identical twins – resuglt from the splitng in half of the izygote, resugltng in each of the
two resugltng izygotes having exactly the same set of genes
fraternal twins – resuglt when two eggs happen to be released into the fallopian tugbe
at the same tme and are fertliized by two diferent sperm (only half of genes in
common)
implantaton happens afer the 1st week – here the izygote embeds itself in the ugterine
lining and becomes dependent on the mother for sugstenance (afer 2nd week
completely embedded)
afer implantaton, the inner cell mass becomes the embryo and the rest of the cells
become an elaborate sugpport system (incl. amniotc sac & placenta)
o inner cell mass three layers
Newborn Period
Prenatal Development
Great diferences in how people have thougght abougt prenatal development
4th centugry B.C.: Aristotle Does prenatal life start with new individugal, already
performed, composed of a fugll set of tny parts, or do the many parts of the hugman
body develop in sugccession?
o ugnderlying western thougght for next 15 centugries
o rejecton of preformaton (epigenesis) – the emergence of new strugctugres and
fugnctoning dugring development
example: Beng Beginnings (people in Ivory Coast of West Africa) believe in
reincarnaton of ancestors
o frst weeks afer birth: the ancestors spirit “wrug”, isn´t fuglly commited to an
earthly life (dougble existence), travels back and forth btw. everyday world and
“wruggbe” (“spirit village”)
o afer the ugmbilical stugmp has dropped newborn has emerged from
“wruggbe” and is a person
o these beliefs ugnderlie many aspects of Beng infant-care practces
1. life begins before birth - reincarnaton of ancestor
2. life begins also afer birth – when the individugal has become a person
Concepton
gametes (germ cells) – reprodugctve cells (egg and sperm) that contain only half the genetc
material of all the other cells in the body
gametes are produgced througgh meiosis – cell division in which eggs and sperm receive only
one member from each of the 23 chromosome pairs necessary for reprodugcton
reprodugcton starts with the laugnching of an egg from one of the woman´s ovaries
into the adjoining fallopian tugbe
as the egg moves througgh the tugbe toward the ugterugs, it emits a chemical sugbstance,
a “come-hither” atractng sperm toward it
conception – the ugnion of an egg and a sperm – is possible if sexugal intercougrse takes
place near that tme
jougrney sperm: 6 hougrs, 6-7 inches from the vagina ugp througgh the ugterugs to the egg-
bearing fallopian tugbe
high failugre rate (1 million sperm cells, bugt only 200 approach the egg)
o chance
o seriougs genetc or other defects
as sperm´s head penetrates the ougter membrane of the egg, a chemical reacton
seals the membrane, preventng other sperm from entering
the nugclei of the 2 cells merge within 2 hougrs
zygote – fertliized egg cell
process 9 month (38 weeks/266 days)
, Developmental Process
ugnderlying the transformaton of a zygote into an embryo (-developing organism from 3rd to
8th week) and fetus (-developing organism from 9th week to birth)
1. cell division – mitosis (cell division resugltng in two identcal daugghter cells)
o within 12 hougrs afer fertliizaton izygote divides into 2 equgal parts with a
fugll complement of genetc materiall then into 4, 8, 16, etc. newborn
consistng of trillion cells
2. cell migraton – the movement of newly formed cells away from their point of origin
(e.g. neugrons)
3. cell diferentaton – embryonic stem cells (-embryonic cells, which can develop into
any type of body cell) start to specialiize in strugctugre and fugncton (350 diferent types
of cells)
o key determinants: “switched on”/ expressed cellsl locatonl inital exibility
4. cell death – apoptosis (genetcally programmed cell death)
Hormones are crugcial in prenatal development if androgens are present, male sex organs
develop (sougrce of androgens is the fetugs itself, arougnd the 8th week afer concepton tests
begin to produgce these hormones)
Sex diferences
male bias at birth: more male embryos were conceived than female ones
o male fetugses are more sugsceptble to spontaneougs aborton than females in
the 1st week and last weeks of pregnancy
o male infants are more likely to be born at very low birth weight and are less
likely to sugrvive
stugdy:
o concepton is equgally likely
o female fetugses are less likely to sugrvive early gestaton
o boys are more likely to experience fetal distress dugring labor & delivery
o male infants are more likely to die from sugdden infant death syndrome
o in many societes, both historically and cugrrently, male ofspring are more
highly valuged, and therefore more likely to sugrvive
Early Development
identical twins – resuglt from the splitng in half of the izygote, resugltng in each of the
two resugltng izygotes having exactly the same set of genes
fraternal twins – resuglt when two eggs happen to be released into the fallopian tugbe
at the same tme and are fertliized by two diferent sperm (only half of genes in
common)
implantaton happens afer the 1st week – here the izygote embeds itself in the ugterine
lining and becomes dependent on the mother for sugstenance (afer 2nd week
completely embedded)
afer implantaton, the inner cell mass becomes the embryo and the rest of the cells
become an elaborate sugpport system (incl. amniotc sac & placenta)
o inner cell mass three layers
