PSY 302 Chapter 4: ch4
prenatal development and the newborn period
• Understanding the time period spent in the womb of the mother and premature babies
Beng Beginnings
• Beng- people in the ivory coast of west africa - who belief that every newborn is a reincarnation
of ancestor -- so if the newborn dies, there is no funeral that will be held bc it is only perceived as
a return to the wrugbe ( spirit village)
• They believe that there is constant danger that the infant will become homesick for its life in
wrugbe and decide to leave earthly existence and thus parents try to make babies comfortable and
happy so they wish to stay in the life -- including decorating the child’s face and body to elicit
positive attn from others
• They view prolonged crying as a result to the baby wishing to have a new name- the one from its
previous life in wrugbe
• Life is viewed to have started long before brith since each newborn is a reincarnation of ancestor
The prenatal period: conception to birth
• In the 4th century BC: aristotle asked the fundamental question- does prenatal life start with the
new individual already preformed, composed of a full set of tiny parts, or do many parents of the
human body develop in succession?
• Aristotle believed in epigenesis: the emergence of new structure and fxns in the course of dev
• Aristotle rejected the idea of preformation-- where prenatal life starts with the new individual
already preformed, composed of a full set of tiny parts -= however the idea continued to persist
after aristotle, with the belief that a miniature, preformed human was lodged inside the mother’s
egg or father’s sperm
Conception
• Each individual originates from single cell that resulted from union of two gametes ( sperm from
father and egg from mother) -- containing half the genetic material found from other cells
• Gametes : reproductive cells: that contain only half the genetic material of other somatic cells
• Meiosis: cell division that produces gametes
• Conception: union of egg from the mother and sperm from the father
o Egg will be released from ovaries and travel down fallopian tube and reach the uterus and
unites with sperm
o 500 million sperm are released upon every ejaculation -- they have a long tail that whips
around to properl the sperm through the woman’s reproductive system -- which may take
up to 6 hours - journeying 6-7 inches from the vagina to the uterus -- although million
enter, only about 200 get near the egg ( the best of the best)
▪ Many complications occur - including sperm travelling to the wrong fallopian
tube that doesnt have egg, get tangled with other sperm, others have genetic
defects that prevent them from propelling themselves from having the ability to
move enough to reach and fertilize the egg --- thus the sperm that reaches the egg
must be relatively healthy and structurally sound ( survival of the fittest)
▪ Once the sperm head penetrates the outer mem of the egg, chemical rxn seal the
mem preventing other sperm from entering -- the tail of the sperm falls off, and
contents of the head gush into the egg and the nuclei of the two cells merge
within hours
▪ Fertilized egg= zygote -- with 23 chromosomes from mother and 23 from father
▪ Prenatal dev begins and will continue for about 9 months
Individual differences: the first-and last- sex differences
• Male fetuses= more susceptible to spontaneous abotion thatn females in both the 1st week and
last several weeks of pregnancy
o More likely to be born with low birth weights and less likely to survive than females
o Male bias at birth ?
o More likely to experience fetal distress than girls -- less able to tolerate stress of childbith
o Over cultural contexts, infant mortality tended to be higher for boys than girls
o More likely to die from sudden infan death syndrome (SIDS)
o Boys suffer disproportionately from most development disorders including language and
learning disorders, dyslexia, attention deficit disorder, intellectual disorders and autism
o Frailty for males continues throughout life,, where ado boys are more impulsive and take
more risks than girls-- more likely to commit suicide or die violently
o However hisotircally and currently in some societies, male offspring are more highly
valued ,,, parents resort to infanticide to avoid having daughters -- i
▪ e: inuit families in northern family-- traditionally depended on male children to
help hunt for food, and in former times, inuit girls would be often killed at birth
▪ Until 2015, the chinese govt enforced 1 child policy- leading to many girl
newborns being killed or abandoned in order to make room for male child
▪ In tech advanced countries that still value male newborns over female may
determine the gender of the fetus and have female fetuses selectively aborted
• Female fetuses- more susceptible to spontaneous abortion during weeks 10-15
• Most recent study- suggest that conception is equally likely to result in male and female embryos
-- results show that female fetuses are less likely to survive early gestation, resulting in slight
male bias at birth
Developmental processes
• Embryo: the name given to the devleoping organism from the 3rd to the 8th week of prenatal dev
• Fetus: the name given to the developing organism from the 9th week to birth
• Mitosis: cell divison that results in two identical daughter cells
• 4 major dev processes
o Mitosis: cell division of the zygote over the 38 weeks of preganncy
o Cell migration: movement of newly formed cells away from their point of origin
o Cell differentiation: initially all embryo cells= embryonic stem cells ( which can dev into
any type of body cell) -- with no fixed fate or fxn -- however after several cell divisions,
the cells spart to specialize in fxn and shape
o Celld eath: selective death of certain cels needs to take place during the dev process --
cell apoptosis ( genetically programmed cell death) - readily apparent in head dev --
where the formation fo fingers depends on the death of the cells in btwn the ridges in the
hand plate -- death is preprogrammed for the cells that disappear from the hand plates
• Hormones also play key role in sexual differentiation
o Presence of testosterone- male genitalia will dev if absent, female genitalia will dev
▪ Based on the presence or absence of testosterone
▪ The source of the androgens is from the male fetus itself
Early dev
• Identical twins: twins that result from the splitting in half of the zygote, resulting in each of the
two resulting zygotes having exactly the same set of genes
• Fraternal twins: twins that result when two eggs happen to be released into the fallopian tube at
the same time and are fertilized by two different sperm; fraternal twins have only half their genes
in common
• By end of 1st week after fertilization, implantation takes place where the zygote embeds itself in
the uterine lining and becomes dependent on the mother for sustenance -- the inner cell mass
Document Summary
Prenatal development and the newborn period: understanding the time period spent in the womb of the mother and premature babies. - results show that female fetuses are less likely to survive early gestation, resulting in slight male bias at birth. 12 months -- however pregnancy outcomes are worse for mothers who are depressed and their children are at risk for social and cognitive challenges due to suboptimal maternal-infant interactions. Fetal alcohol syndrome (fas) involves a range of effects, including facial deformities, mental retardation, attention probs, hyperactivity, and other defects. Fetal acohol effects (fae) is a term used for indviidual who show some, but not all fo the standard effects of. Fas: even moderaet drinking during pregancy canhave short and long term neg effects on dev. Including low birth weight, increased riskof adhd, and delays in cognitive dev and school achievement: env pollutants:
