postnatal development lecture and tutorial Flashcards
at what stage is adult heigh+ growth influenced the most by genetics? prenatal or postnatal?
prenatally genetics of the baby have a minor effect overall on adult height/ growth
vs postnatally genetics Largely determine final adult height
Sex chromosomes have an effect:
XY boys are taller than XX girls
since we saw the babies genes dont influence prenatal growth much, what does influence the babies growth prenatally?
maternal size - birth size
maternal factors oVERRIDE fetal genetic factors in determining prenatal growth
what is the effect of paternal genetic factors on prenatal growth?
little effect
what are the main endocrine factors influencing prenatal growth?
Insulin and insulin-like growth factors (IGFs) are major prenatal hormones influencing growth:
at what stage is GH responsible for growth?
ONLY POSTNATALLY -MAJOR HORMONE controlling growth but prenatally it doesn’t influence growth AT ALL
what is the role of IGF-2 in growth?
MOST important growth factor for EMBRYONIC growth
what is the role of IGF-1
MOST important growth factor for later fetal and infant growth
what two things are very relevant/ influential to prenatal nutrition?
placental health
maternal diet (influences nutritional availability)
why is the placenta so important in prenatal growth?
Placenta provides all NUTRIENTS to growing fetus, therefore essential for growth
Placenta also controls HORMONES necessary for fetal growth
most common cause of intrauterine growth restriction?
Placental insufficiency most common cause of intrauterine growth restriction
a fact that highlights the key role of placenta in growth? (abnormality related)
Placental insufficiency most common cause of intrauterine growth restriction
what fact illustrates that adequate nutrition is essential for growth postnatally?
Starvation due to lack of substrate availability as a can limit growth POTENTIAL
as a result of what does obesity MOSTLY occur postnatally?
excessive intake of food
what may poor nutrition lead to in terms of growth postanatlly?
DELAY the ONSET of puberty
what may malabsorption of nutrients cause postnatally?
reduced growth
what two environmental factors are important for fetal growth prenatally? and which is most important?
uterine capacity and placental sufficiency.
placental function is MORE INFLUENTIAL
WHAT environmental factors are important to growth postnatally?
Socioeconomic status
Chronic disease
Emotional status
Altitude (mediated by lower oxygen saturation levels)
comment on the size of the head at birth.
Head disproportionately large for the body (1/3rd vs 1/7th in adulthood) at birth
how long does the most rapid postnatal growth stage last and when does it occur?
infantile stage, for approx 2 years
what is the state of the cranial sutures at birth? what happens to them during early years and by what month exactly?
Cranial sutures open at birth, close by 18months
four recognised phases of growth in order + their length ?
Fetal (prenatal)
Infantile 0-18 months
Childhood 18 months- 12 yrs
Pubertal 12 yrs+
rank the growth phases for % contribution to adult height
1) childhood 40%
2) fetal (in uterine environmetn) 30%
3) infantile and pubertal both 15)
outline some important factors influencing growth in infantile and then childhood stages
good health and happiness
,thyroid hormones, nutrition,
but for childhood endocrine regulation is increasing, moving from this largely nutrition based to more GH and genetic and thyroid horm…
factors influencing pubertal growth
rising levels of testosterone and oestrogen ( sex hormones)
also boost hGH production
what is the fastest growth phase over whole life course?
fetal phase
what are 2 important differences about growth rate in infantile vs fetal growth phases?
1) fetal is higher rate
2) Fetal is ACCELERATING vs infantile is DECELERATING
compare how much growth occurs during fetal vs infantile phase
fetal: Fetus repeatedly doubles in size over gestation
infantile: Length increases by 50%, head circumference by 30% and weight triples from birth
compare the growth happening in fetal (prenatal) vs postnatal phases on a CELLULAR level
Growth mainly driven by HYPERPLASIA (number of cells) during fetal life:
~42 cycles of cell division before birth,
~only further five cycles of cell division occur from birth to adulthood.
so more cell SIZE growth
- this also adds up with growth being largely NUTRITION dependent at infantile phase
what happens to the growth rate during childhood and puberty
childhood theres a steady prolongued growth and then puberty a sudden growth spurt
compare how much growth happens in childhood and puberty.
childhood:
5-6 cm annual increase in height, and 3-3.5kg annual increase in weight
pubertal
25cm (XY boys) ~20cm (XX girls) increase in height over 3-4 years
childhood slower but more overall growth bc it lasts longer - more years
but puberty more growth per year- greater rate
what physiological mechanism ensures that puberty is only a TEMPORARY growth spurt?
although they boost GH, sex hormones also eventually cause fusion of growth plates
what are the 6 different phases of reproductive hormones over life and what happens in each
fetal- development of sexual organs and the GnRH network- the actual physical brainparts - rise in HPG activity
then HPG activity drops
neonatal- priming of HPG axis called MINI- puberty (lasts around first 6 months of life)
childhood- low/ no HPG activity linear growth and developmental milestones,
adolescence- increasing HPG activity: sexual maturation
adult: HPG activity stabilizes - straight line
2 phases where we see greatest increase in HPG axis activity
neonatal (Mini puberty) and puberty
two phases where HPG axis activity is linear, not changing
childhood ( constant no activity )
adulthood (constant activity)
what is the pattern of gonadotrophin secretion throughout prenatal and postnatal development
prenatal:
1) GONADOTROPHIN (LH +FSH) secretion starts towards the END of the 1st TRIMESTER, peaks MID PREGNANCY then declines
postnatal
2) HPG axis transiently activated after birth (MINI PUBERTY) due to release form restraint by placental hormones
continues for around 6 months after birth before declining
what is different about the pattern of oestorgen compared to testosterone and at what stage?
after birth, testosterone increases (peaks around 2 months) then decreases while oestrogen keeps fluctuating around every months
role of elevated sex steroids during mini puberty in males
important for normal gonadal development (WITHOUT spermatogenesis)
role of minipuberty in females
less clear,
there is follicular development occuring in the ovary at that time so could be that
maybe important for patterning and development of mammary tissue?
other than gonadal development and sex- related development, what other thing can the sex steroids in minipuberty also influence later in life?
programming of body composition and linear (height) growth.
ex. High testosterone levels in boys during minipuberty, may partly explain the higher growth velocity observed in boys compared to girls.
what triggers puberty and what influences its onset
Control of puberty onset remains unclear, but influenced by metabolic status.
what is one possible amechanism triggering puberty and what is the evidence for it
1) KNDy neurons (Kisspeptin/Neurokinin B/Dynorphin)
2) release neurokinin,
3) regulating release of KISSPEPTIN peptides,
4) which act on GnRH neurons to promote pulsatile GnRH release
proof:
Mutations in KISS1R affect puberty timing, implicating Kisspeptin-KISS1R signalling in regulation of this process.
(ex a silencing mutation leads to no pubertyect)
what is consonance
COMPLIANCE with a PREDICTABLE PATTERN of developmental events during PUBERTY
has consonance changed in the past?
yes,
age of menarche decreased by 4 yrs 1850s - 1960s then by 3 more months per decade form 1977-2013
when do pubertal processes typically start and end for girls and boys
8- 16.5 GIrls
10.5-18 boys
what is the consonance for female pubertal developmental events
breast budding
pubic hair
(the first two start together ish)
growth spur
menarche
armpit hair
body shape
adult breast size
what is the consonance for male pubertal developmental events
scrotal and testicular growth
change in voice
(first two start together ish)
penile lengthening
pubic hair
growth spur
body shape changes
facial and armpit hair
what are the developmental domains
gross motor skills
fine motor skills
social behaviour and play skills
speech, language and hearing skills
developmental milestones by median age
what are the aims of the NHS healthy child programme
PREVENT disease,
PROMOTE good health
aims to be
universal in order to reduce health inequalities
just some epidimiological stats illustrating why theres need for NHS healthy child programme
1 in 25 children are born with a genetic disorder,
1 in 45 children with a congenital birth defect,
1 in 10 experience some kind of developmental delay in childhood.
what specific processes does healthy child programme carry out?
Health Promotion (Obesity prevention is a key aspect)
Supporting care giving and care givers
(in my head these match thematically)
immunisation
Screening
Identification of high-risk families/ individuals for additional support
Signposting for
accident prevention
dental hygiene
Fundamentals of a Good Screening Test…
relating to the disease its screening for:
1) able to be identified early
2) treatable
3) able to prevent mortality/ reduce morbidity
acceptable and easy to administer
cost effective
reproducible and accurate results
Examples of Important Early Childhood Screening:
newborn check
newborn hearing screen
blood spot check (the blood analysis from heel prick - collection method)
NHS health and development baby reviews, which are they, when do they hapena dn what do they include?
Newborn physical exam (within 72h) – weight, eyes, heart, hips and testes
Blood spot test (within 7d, ideally d5) – CF, Sickle Cell, congenital hypothyroidism, inherited metabolic diseases (eg PKU)
Newborn hearing test (3-5 weeks) – sometimes done in hospital before discharge, can be done up to 3 months
Infant physical exam (6-8 weeks) – with GP, as newborn physical, with length and head circumference – opportunity to discuss vaccinations.
what is sure start?
programme trying to prevent for stuff, has succeded in reducing accidents in older kids (10-11) even though intervention is in earlier years
has also reduced inequalities
invests a lot in childrens community centres (day care schools ect)
aims to help support families with under 5s in LOW INCOME HOUSEHOLDS
PARENT AND CHILD EDUCATION
what is global developmental delay
SIGNIFICANT delay in reaching 2 or more developmental milestones
what is specific developmental disorder
refers to delays in developmental domains
in the absence of sensory deficits, suboptimal intelligence
or poor educational environment.
- learning disorders
- motor skill disorders
- communication disorders
causes of global developmental delays
Chromosomal abnormalities
e.g. Down’s syndrome, Fragile X
Metabolic
e.g. hypothyroidism, inborn errors of metabolism
Antenatal and perinatal factors
Infections, drugs, toxins, anoxia, trauma, folate deficiency
Environmental-social issues
Chronic illness
Causes of motor skill developmental delay
As an aspect of global developmental delay
Cerebral palsy
Congenital dislocation of the hip
Muscular dystrophies
Neural tube defects
Social deprivation
Causes of language skill developmental delay
Hearing loss
Autism spectrum disorders
Lack of stimulation
Impaired comprehension of language – e.g. developmental dysphasia
Impaired speech production – e.g. stammer, dysarthria
what are some tests testing for language skill development and what age is each appropriate for
Schedule of growing skills (0-5y)
Griffiths developmental scale (0-6y)
Bayley Scales of Infant Development (1m-42m)
Denver developmental screening tests (0-6y) particular age.
which test assesses ability in domains relative to %age blocks of children from a population who could achieve a skill by a particular age.
Denver developmental screening tests (0-6y) –
which test assesses cognitive, motor and language skills
bayley scales of infant development 1m-42m
which test measures trends indicative of functional mental growth and the domains listed above through play activities.
Griffiths developmental scale (0-6y) –
which test is a standardised test examining 8 criteria (Locomotor, manipulative, self-care, social skills, hearing and language, speech and language, visuals and cognitive)
Schedule of growing skills (0-5y)
