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Year 2 - BRS > 10.3 - Postnatal and child development 1/2 > Flashcards

10.3 - Postnatal and child development 1/2 Flashcards

1
Q

What factors can affect prenatal / postnatal growth? (4)

A
  • genetics
  • endocrine
  • nutrition
  • environment
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2
Q

How do genetics affect prenatal growth?

A
  • minor effect overall
  • maternal size important in determining birth size
  • paternal genetic factors have little effect on birth
  • maternal factors tend to override foetal genetic factors in determining prenatal growth
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3
Q

How do genetics affect postnatal growth?

A
  • largely determines final adult height
  • sex chromosomes have an affect:
  • XY boys are taller than XX girls
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4
Q

How do endocrine factors affect prenatal growth?

A
  • 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 foetal and infant growth
  • (growth hormone has no effect on early growth)
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5
Q

How do endocrine factors affect postnatal growth?

A

Human growth hormone (hGH) is the major hormone controlling growth after birth

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6
Q

How does nutrition affect prenatal growth?

A
  • placenta provides all nutrients to growing foetus, therefore essential for growth
  • placental insufficiency most common cause of intrauterine growth restriction
  • placenta also controls hormones necessary for foetal growth
  • maternal diet influences nutritional availability
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7
Q

How does nutrition affect postnatal growth?

A
  • adequate nutrition is essential for growth
  • starvation due to lack of substrate availability can limit growth potential
  • obesity mainly occurs as a result of excessive intake of food
  • poor nutrition may delay the onset of puberty
  • malabsorption of nutrients may cause reduced growth
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8
Q

How does the environment affect prenatal growth?

A
  • uterine capacity and placental sufficiency important in providing optimal environment for foetus
  • placental function is more influential in foetal growth than uterine capacity
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9
Q

How does the environment affect postnatal growth?

A

The following factors are known to influence growth:

  • socioeconomic status
  • chronic disease
  • emotional status
  • altitude (mediated by lower oxygen saturation levels)
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10
Q

What is the size of the head like at birth, and how does this change?

A

Head disproportionately large for the body at birth (1/3rd vs 1/7th in adulthood)

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11
Q

What is the overall growth (of the head?) like in the first two years of life vs after, and why?

A
  • grows rapidly for the first 2 years, before slowing down
  • cranial sutures open at birth and close by 18 months
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12
Q

What are the four recognised phases of growth (and what % of adult height do they contribute to)?

A
  • fetal (30%)
  • infantile (15%)
  • childhood (40%)
  • pubertal (15%)
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13
Q

What is important in the fetal phase of growth?

A

Uterine environment

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14
Q

What is important in the infantile phase of growth? (3)

A
  • nutrition
  • good health and happiness
  • thyroid hormones
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15
Q

What is important in the childhood phase of growth? (4)

A
  • growth hormone
  • thyroid hormones
  • genes
  • good health and happiness
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16
Q

What is important in the pubertal phase of growth? (2)

A
  • testosterone and oestrogen
  • growth hormone
17
Q

What is the fastest period of growth over the life-course?

A

Fetal growth phase

18
Q

Describe the fetal growth phase.

A
  • fastest period of growth over life-course
  • accounts for approximately 30% of eventual height
  • foetus repeatedly doubles in size over gestation
  • growth mainly driven by hyperplasia during fetal life:
    • ~42 cycles of cell division before birth
    • ~only further 5 cycles of cell division from birth to adulthood
19
Q

What is growth in the fetal growth phase mainly driven by?

A

Hyperplasia (cell division)

20
Q

Describe the infantile growth phase.

A
  • covers 0-18 months after birth
  • accounts for approximately 15% of eventual height
  • rapid, but decelerating growth (compared to fetal phase)
  • length increases by 50%, head circumference by 30% and weight triples (vs birth)
  • growth largely nutrition dependent
21
Q

What is growth in the infantile growth phase largely dependent on?

A

Nutrition

22
Q

Describe the childhood growth phase.

A
  • covers 18 months to 12 years of age
  • accounts for approximately 40% of eventual height
  • steady, slow, prolonged growth
  • 5-6cm annual increase in height, 3-3.5kg annual increase in weight
  • good nutrition and health important, but endocrine growth regulation increasing
23
Q

Describe the pubertal growth phase.

A
  • AKA pubertal growth spurt
  • accounts for 15% of eventual height
  • rising levels of sex hormones boost human growth hormone (hGH) production
  • ~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
24
Q

Why is the pubertal growth phase only a temporary growth spurt?

A

Temporary growth spurt as sex hormones also cause fusion of growth plates

25
Q

Describe the activity of the HPG axis over the life-course.

A
  • fetal - development of sexual organs and GnRH network, foetal HPG axis activity peaks around 20 weeks
  • neonatal - priming of HPG axis, ‘mini-puberty’
  • childhood - linear growth and developmental milestones, HPG shut down until puberty
  • adolescence - sexual maturation, normal puberty, HPG activity rises
  • adulthood - reproductive capacity, HPG activation stays high
26
Q

Describe gonadotrophin secretion during pregnancy.

A

Gonadotrophin secretion commences towards the end of the first trimester, peaks mid-pregnancy, then declines

27
Q

What is mini-puberty?

A
  • HPG axis transiently activated after birth (mini-puberty), after release from restraint by placental hormones
  • continues for around 6 months after birth before declining

Males: T elevated
Females: E2 fluctuates

28
Q

What is the point of mini-puberty?

A
  • elevated sex steroids in males during mini-puberty seems to be important for normal gonadal development (testicular tissue and penile development)
  • role of mini-puberty less clear in female infants:
    • oestradiol levels fluctuate through first few months after birth
    • follicular development occurs in the ovary
    • important for patterning and development of mammary tissue?
  • elevated sex steroids in mini-puberty may also influence programming of body composition and linear growth
    • high testosterone levels in boys during mini-puberty may partly explain the higher growth velocity observed in boys vs girls
29
Q

What triggers puberty?

A
  • 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
  • mutations in KISS1R affect puberty timing, implicating Kisspeptin-KISS1R signalling in regulation of this process
  • adiposity also plays a role
30
Q

What do the developmental events of puberty typically follow?

A

The developmental events of puberty typically follow a predictable pattern

31
Q

What is compliance with the predictable pattern of developmental events of puberty known as?

A

Consonance

32
Q

How has the age of menarche changed?

A

Decreased ~4y from 1850-1960, then by a further 3 months per decade from 1977-2013 (partly due to better nutrition and health status)

33
Q

Describe the developmental milestones during puberty in a female.

A
  • breast budding
  • growth of pubic hair
  • growth spurt (peak)
  • first period (menarche)
  • growth of underarm hair
  • change in body shape
  • adult breast size
34
Q

Describe the developmental milestones during puberty in a male.

A
  • growth of scrotum and testes
  • change in voice
  • lengthening of penis
  • growth of pubic hair
  • growth spurt (peak)
  • change in body shape
  • growth of facial and underarm hair
35
Q

What are the four developmental domains?

A
  • gross motor skills
  • fine motor skills
  • speech, language and hearing skills
  • social behaviour and play skills
36
Q

Describe the development of gross motor skills.

A
  • newborn: flexed posture
  • 7 months: sits without support
  • 1 year: stands independently
  • 15-18 months: walks independently
  • 2.5 years: runs and jumps
37
Q

Describe the development of fine motor skills and vision.

A
  • newborn: fixes and follows face/object
  • 7 months: palmar grasp (4-6 months), transfers objects from hand to hand
  • 1 year: pincer grip (10 months), points
  • 15-18 months: immature grip of pencil, random scribble
  • 2.5 years: draws
38
Q

Describe the development of speech, language and hearing skills.

A
  • newborn: stills to noise, startles to loud noise
  • 7 months: turns to voice, polysyllabic babble
  • 1 year: 1-2 words, understands name
  • 15-18 months: 6-10 words, points to four body parts
  • 2.5 years: 3-4 word sentences, understands two joined commands
39
Q

Describe the development of social behaviour and play, emotional and behavioural skills.

A
  • newborn: smiles by 6 weeks
  • 7 months: finger feeds, fears strangers
  • 1 year: drinks from cup, waves
  • 15-18 months: feeds self with spoon, beginning to help with dressing
  • 2.5 years: parallel play, clean and dry

Year 2 - BRS (84 decks)

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