1B postnatal and child development Flashcards
Explain the effect of genetics on prenatal development
- Minor effect overall
- Maternal size important in determining birth size
- Paternal genetic factors have little effect on birth
- Maternal factors tend to override fetal genetic factors in determining prenatal growth
Explain the effect of genetics on postnatal development
- Largely determines final adult height
- Sex chromosomes have an effect:
- XY boys are taller than XX girls
Explain the endocrine effects on prenatal development
- Insulin and insulin-like growth factors (IGFs) are major prenatal hormones influencing growth:
- IGF-2 most important for embryonic growth
- IGF-1 most important for later fetal and infant growth
- (Growth hormone has no effect on early growth)
Explain the endocrine effect on postnatal development
Human growth hormone (hGH) is the major hormone controlling growth after birth
Explain the effect of nutrition on prenatal development
- Placenta provides all nutrients to growing fetus, therefore essential for growth
- Placental insufficiency most common cause of intrauterine growth restriction
- Placenta also controls hormones necessary for fetal growth
- Maternal diet influences nutritional availability
Explain the effect of nutrition on postnatal growth
- Adequate nutrition is essential for growth
- Starvation due to lack of substrate availability as a can limit growth potential
- Obesity occurs mostly as a result of excessive intake of food
- Poor nutrition may delay the onset of puberty
- Malabsorption of nutrients may cause reduced growth
Explain the environmental effects on prenatal growth
- Uterine capacity and placental sufficiency important in providing optimal environment for fetus
- Placental function is more influential in fetal growth than uterine capacity
Explain the environmental effect on postnatal growth
The following factors are known to influence growth:
- Socioeconomic status
- Chronic disease
- Emotional status
- Altitude (mediated by lower oxygen saturation levels)
Describe postnatal growth including the four recognised phases of growth
- Head disproportionately large for the body (1/3rd vs 1/7th in adulthood) at birth
- Grows rapidly for the first 2 years, before slowing
Cranial sutures open at birth, close by 18months
Four recognised phases of growth:
- Fetal
- Infantile
- Childhood
- Pubertal
Describe fetal phase
- Fastest period of growth over life-course
What ages does infantile phase cover?
Covers 0-18 months after birth
What ages does childhood phase cover?
18 months to 12 years of age
What contribution does childhood phase have to eventual height
Approximately 40%
How is growth in childhood phase characterised?
Steady, slow prolonged growth
- 5-6 cm annual increase in height, and 3-3.5kg annual increase in weight
What factors are important in childhood phase?
Good nutrition and health important, but endocrine growth regulation increasing
What contribution does infantile have to eventual height?
Accounts for approximately 15% of eventual height.
How is growth in infantile phase characterised?
- Rapid, but decelerating growth (vs fetal phase)
- Length increases by 50%, head circumference by 30% and weight triples vs birth
What factors are important in infantile phase?
Growth largely nutrition dependent
What contribution does the pubertal phase have to eventual height?
15% of eventual height
- ~25cm (XY boys) ~20cm (XX girls) increase in height over 3-4 years
- Temporary growth spurt as sex hormones also cause fusion of growth plates
What significant event happens during pubertal phase?
Rising levels of sex hormones boost hGH production
What contribution does fetal phase have on eventual height?
Accounts for approximately 30% of eventual height.
- Fetus repeatedly doubles in size over gestation
What is growth mainly driven by in fetal phase?
- Growth mainly driven by hyperplasia (cell number) during fetal life:
- 42 cycles of cell division before birth
- only further five cycles of cell division occur from birth to adulthood
Describe reproductive hormone changes over childhood
What is mini-puberty?
- Gonadotrophin secretion commences towards the end of the first trimester, peaks mid-pregnancy, then declines
- HPG axis is transiently activated after birth (mini-puberty), after release from restraint by placental hormones
- Continues for around 6 months after birth before declining
What is the point of mini-puberty in males?
Elevated sex steroids in males during mini-puberty seems to be important for normal gonadal development (testicular tissue and penile development)
What is the role of minipuberty in female infants?
Role of minipuberty less clear in female infants:
- Estradiol levels fluctuate through first few months after birth
- Follicular development occurs in the ovary
- Important for patterning and development of mammary tissue?
What is the effect of elevated sex steroids in minipuberty?
Elevated sex steroids in minipuberty may also influence programming of body composition and linear growth.
High testosterone levels in boys during minipuberty, may partly explain the higher growth velocity observed in boys compared to girls.
What triggers puberty?
Control of puberty onset remains unclear, but influenced by metabolic status.
Release of neurokinin KNDy neurons may regulate release of Kisspeptin peptides, which act on GnRH neurons to promote pulsatile GnRH release
What mutations affect puberty timing and what does it implicate?
- Mutations in KISS1R
- Implicates Kisspeptin-KISS1R signalling in regulation of puberty triggering
What is consonance?
The compliance of the sequence of developmental events of puberty that typically follow a predictable pattern
How have developmental milestones changed during puberty across the decades?
Age of menarche decreased by ~4 years 1850-1960, then by a further 3 months per decade from 1977-2013
What are the four developmental domains?
- Gross motor skills
- Fine motor skills
- Speech, language and hearing skills
- Social behaviour and play skills
How do newborn babies look when lying flat?
Limited flexed, symmetrical posture
- When body is lifted, there is marked head lag due to neck muscles not having developed properly yet
At 6-8 weeks how well can babies raise their head?
Head raise to 45° in prone
What happens at 6-8 months?
Sits without support
- At 6 months- with round back
- At 8 months- with straight back
What action can babies do well by 4-5 months?
Rolling around
What gross motor skill can babies do by 8-9 months?
Crawl around
What can babies do by 10 months?
Stand up and cruise around furniture
What can babies do in 12 months?
Walks unsteadily, broad gait, hands apart
What can babies do in 15 months?
Walk steadily
By 6 weeks what can babies do coordination wise?
Follow moving object or face by turning the head
Vision and fine motor wise, what can babies do in 4 months?
Reaching out for toys
What can the baby do by 4-6 months with its hands?
Palmar grasp
What can the baby do by 7 months with its hands?
Transferring toys from one hand to another
What can babies do by 10 months grip wise?
Mature pincer grip
What can babies do by 16-18months grip wise?
Make marks with a crayon
By the time the child reaches 4 how does their hand-eye coordination develop?
Becomes quite sophisticated e.g. can build increasingly more difficult structures with building blocks
By the time the child reaches 4 how does their hand-eye coordination develop in drawing?
Through 2-5 years they can draw without seeing how it’s done and can copy from 6 months earlier after seeing how it’s done
How do newborns react to noise?
Startled by loud noises
What can babies do by 3-4 months language wise?
Vocalise alone or when spoken to, coos and laughs
How do babies react to sound at 7 months?
Turn to soft sounds out of sight
What can babies do by 7-10 months language wise?
- At 7 months, sounds used indiscriminately
- At 10 months, sounds used discriminately to parents
- Polysyllabic babble heard at this stage with tones and variations
What can babies do by 12 months language wise?
2 or 3 words other than dada or mama
What can toddlers do at 18 months language wise?
6-10 words and show 2 parts of the body
What can a child do at 20-24 months language wise?
Use 2 or more words to make simple phrases e.g. give me teddy
What can child do at 2.5-3 years language wise?
Talk constantly in 3-4 word sentences
What social behaviour can babies do at 6 weeks?
Smiling responsively
What social behaviour can babies do 6-8 months?
Self-feeding
What social behaviour can babies do at 10-12 months?
Wave bye bye and play peek a boo
What can babies do at 12 months social behaviour wise?
Encourage parents to get rid of bottle to aid speech and language development- prolonged usage of juice bottles can also lead to dental caries
What can kids do at 18 months behaviour wise?
Hold spoon and get food safely to mouth
What can kids do at 18-24 months behaviour wise?
Symbolic play i.e. imaginary play
What can children do at 2 years behaviour wise?
- Potty training
- Pull off some clothing
What can children do at 2.5-3 years?
Parallel play with other kids
What are the fundamentals of a good screening test?
- The disease it is screening for should be:
- Able to identified early/before critical point
- Treatable
- Prevent/reduce morbidity/mortality
- Acceptable/easy to administer
- Cost effective
- Reproducible and accurate results
What health and development baby reviews are done by the NHS?
- Newborn physical exam
- Blood spot test
- Newborn hearing test
- Infant physical exam
When is the newborn physical exam performed?
Within 72hrs of birth
What does the newborn physical exam review?
Weight, eyes, heart, hips and testes
When is the blood spot test done?
Within 7 days, ideally day 5
What does the blood spot test assess?
CF, sickle cell, congenital hypothyroidism, inherited metabolic diseases (e.g. PKU)
When is the newborn hearing test done?
3-5 weeks
Sometimes done in hospital before discharge, can be done up to 3 months
When is the infant physical exam performed?
6-8 weeks
Where is the infant physical exam done?
With GP, as newborn physical, and head circumference- opportunity to discuss vaccinations
What are the causes of global developmental delay?
- 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
What are causes of language skill development delay?
- Hearing loss
- Autism spectrum disorders
- Lack of stimulation
- Impaired comprehension of language (development dysphasia)
- Impaired speech production (stammer, dyarthria)
What commonly used assessment tools are there?
- Standardised tests
- Schedule of growing skills
- Griffiths developmental scale
- Bailey developmental scale
- Denver developmental screening tests
What causes of motor delay are there?
- Cerebral palsy
- Global delay e.g. Down’s
- Congenital dislocation hip
- Social deprivation
- Muscular dystrophy- Duchenne’s
- Neural tube defects: spina bifida
- Hydrocephalus
What are the two types of developmental delay?
- Global developmental delay
- Specific developmental disorder
What is global developmental delay?
Significant delay in reaching two or more developmental milestones
What is specific developmental disorder?
Refers to delays in developmental domains in the absence of sensory deficits, subnormal intelligence or poor educational conditions:
- learning disorders
- motor skill disorders
- communication disorders
