Pregnancy, developments and health of mother and child
Doc Brown's Biology exam study revision notes
There are various sections to work through, after 1 they can be read and studied in any order.
Sub-index of biology notes on human sexual reproduction
(3) Pregnancy and the development of the embryo and foetus and the
health of mother and child
Around the 14th day of the menstrual cycle
ovulation takes place, and an egg is released from
the ovary and travels down the fallopian tube to the uterus
where it can interact with sperm from sexual intercourse.
Ultimately fertilisation is the fusion of the
nuclei from a male gamete (sperm cell) and a female gamete (egg
gamete of 23 chromosomes + male gamete of 23 chromosome ==>
zygote of 46 chromosomes
For more details see
Genetics - inherited characteristics and human sexual
If a fertilised egg lands
on the uterus lining and becomes implanted, the woman becomes
If so, the level of progesterone
stays at a high level to maintain the lining of the uterus during
pregnancy, hence the period of the menstrual cycle ceases.
If the egg is not fertilised by sperm it will
die after about a day and pass out through the vagina and
menstrual cycle will continue as normal.
The development of the fertilised egg, embryo, foetus
About 24 hours after fertilisation the
fertilised egg undergoes mitosis cell division i.e. splits into two
cells. After about 4 days further mitosis cell division results in an
embryo of 32 cells.
About a week after ovulation, copulation,
fertilisation and cell division, the embryo develops to the
point when it can implant (embed) itself into the wall of the
uterus in the womb
Then the placenta begins to develop so oxygen
and nutrients from the mother can reach the embryo (later foetus
and baby), and waste products removed.
The early stages of foetal development are
characterised by increasing complexity whereas the later stage
development is characterised by increase in size.
After ~a month the embryo is ~6 mm long and now
has a brain, head, eyes, ears and legs.
After ~9 weeks the body is ~25 mm long and
amazingly, completely formed and is now called a foetus.
After ~3 months the foetus is ~54 mm long and
begins to look like a baby.
After ~5 months the foetus is ~160 mm long and
can start kicking and fingernails can be felt.
After ~7 months, the foetus is ~370 mm and is
considered viable - meaning it has a good chance of
surviving if it was born prematurely before completion of the
normal gestation period of 9 months.
After ~9 months (~39-40 weeks) the 'baby' is now ~
520 mm long, fully developed and ready to be born.
importance of good health in pregnancy - antenatal care
The placenta and umbilical cord allows the blood of the mother and
foetus to interact through membranes (but not directly) so
nutrients and oxygen reach the foetus and waste products are
Under any circumstances, good health, i.e. free
of any health issues, is desirable, put health is particularly
important for a pregnant woman.
Hopefully, the mother is eating a nutritious
balanced diet and all bodily functions working normally as well
as taking exercise.
A healthy mental state is also important and
most peoples lives require coping with the ups and downs of
It is fundamentally important to avoid drug
abuse, smoking and alcoholic drinks whose consequences for
the unborn child can be devastating.
Harmful substances from these 'activities' can be passed through the
placenta and umbilical cord to enter the bloodstream of the
the development of the foetus can be adversely
affected by harmful chemicals passed on from the mother and the
baby after birth may suffer from health issues after birth.
of the processes involved in labour and birth
Birth begins when the strong muscles of the
uterus begin to contract.
This causes the breaking of the amniotic sac and
fluid surrounding the baby.
The contractions of the muscles in the uterus
wall increase pushing the baby towards the cervix.
The dilation of the cervix begins so the baby
can get through.
The vagina stretches to allow the baby passage
through the vagina.
Immediately after birth, the baby is still
attached to the placenta, and is removed by tying and cutting
the umbilical cord.
The placenta breaks away from the wall of the
uterus and passed out - the delivery of the afterbirth
The relative merits of breast-feeding compared to bottle-feeding
using formula milk
It should be said, that in most cases, the
baby feeding method is a personal choice.
There are many comparison 'pros and cons'
points, so I've just picked out a few examples.
Advantages of breast feeding
Compared formula-milk, the nutrients in
breastmilk are better absorbed and used by the baby,
including carbohydrate sugars, protein and vitamins.
Breastmilk has the best formulation of nutrients for the
baby's brain growth and nervous system development.
Breast milk is better for fighting
infections and other conditions. It is known that breastfed
babies have fewer infections and hospitalizations than
formula milk fed infants. During breastfeeding, antibodies
and other pathogen-fighting factors pass from a mother to
her baby and strengthening its immune system.
Breast milk is free, always fresh and no
need to rush down to the shop for formula milk!
The skin to skin touching is good for
Disadvantages of breast feeding
If the mother takes in particularly harmful
substance in lifestyle choices, they can be passed on
through breast milk e.g. nicotine fro smoking and ethanol
from alcoholic drinks.
Even caffeine from coffee is passed on to
the baby and can cause problems like restlessness and
It is also possible to pass on some
pathogens via breast milk.
Advantages of bottle-milk feeding
With forward planning, convenient, since
either parent (or other carer) can feed the baby a bottle at
any time, a more parental sharing situation.
Some women have problems in breast feeding
e.g. insufficient milk production or too stressful to cope
No harmful toxins are passed from formula
milk, which is sterile too.
Disadvantages of bottle-feeding
Formula milk involves costs, it isn't cheap,
and the poorer the mother's situation, the greater the
relative financial burden.
It is not as nutritious as breast milk,
though it should provide the necessary dietary requirements.
Formula milk cannot match the complexity of mother's breast
It does not provide the same cover for
fighting infections and the baby's immune system development
(see breast feeding above).
For more higher level details on genetics and cell
division see ...
Cell division - cell cycle - mitosis, meiosis, sexual/asexual reproduction,
Genetics - inherited characteristics and human sexual
Keywords, phrases and learning objectives for this part on
pregnancy and health of mother and
Be able to describe a pregnancy in terms of the
development of the embryo, foetus (fetus), fertilised egg in the
Understand the importance of good health of a mother
in pregnancy to produce a healthy child and be aware that harmful
substances can pass through placenta.
Know that breast milk is better than formula milk,
but be able to discuss the advantages and disadvantages of breast
feeding and bottle feeding.
TOP OF PAGE
of biology notes on human sexual reproduction
INDEX of all my BIOLOGY NOTES
This is a BIG website, so try using the [SEARCH
BOX], it maybe quicker than the many indexes!
brown - comments - query?
Basic Science Quizzes for
UK KS3 science students aged ~12-14, ~US grades 6-8
Biology * Chemistry
* Physics for UK
GCSE level students aged ~14-16, ~US grades 9-10
Advanced Level Chemistry
for pre-university age ~16-18 ~US grades 11-12, K12 Honors
Find your GCSE/IGCSE
science course for more help links to all science revision notes
mobile phone or ipad etc. in 'landscape' mode?
SITEMAP Website content © Dr
Phil Brown 2000+. All copyrights reserved on Doc Brown's biology revision notes, images,
quizzes, worksheets etc. Copying of website material is NOT
permitted. Exam revision summaries and references to science course specifications
Using SEARCH some initial results may be ad links you
can ignore - look for docbrown