1b Postnatal and Child Development Flashcards
What are major prenatal hormones influencing growth?
IGF-2 most important for embryonic growth
IGF-1 most important for later fetal and infant growth
What are the environmental factors that affect 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
How does the brain grow in the first 2 years?
Grows rapidly for the first 2 years, before slowing
Cranial sutures open at birth, close by 18months
What are the four recognised phases of growth?
Fetal
Infantile
Childhood
Pubertal
What is the fastest period of growth over the life course?
Fetal phase
What % of eventual height does the fetal phase account for?
30%
What is the main driver of growth in the fetal phase?
Hyperplasia
How many cycles of cell division occur before birth compared to after birth?
- 42 cycles of cell division before birth,
- only further five cycles of cell division occur from birth to adulthood.
What ages are included in the infantile phase?
0-18 months
What % of eventual height does the infantile phase account for?
15%
What happens to length, head circumference and weight during the infantile phase?
Length increases by 50%, head circumference by 30% and weight triples vs birth
What is growth largely dependent on in the infantile phase?
Nutrition dependent
What ages are included in the childhood phase?
18 months - 12 years
What % of eventual height does the childhood phase account for?
40%
What is the annual increase in height and weoght in the childhood phase?
5-6 cm annual increase in height, and 3-3.5kg annual increase in weight
What drives growth in the childhood phase?
Good nutrition and health important, but endocrine growth regulation increasing
What % of eventual height does the pubertal phase account for?
15%
What drives growth in the pubertal phase?
Rising levels of sex hormones boost hGH production
Temporary growth spurt as sex hormones also cause fusion of growth plates
What is the average increase in height in the pubertal phase?
~25cm (XY boys) ~20cm (XX girls) increase in height over 3-4 years
What causes mini-puberty after birth?
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 importance 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 could be potential role of mini puberty in females?
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 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 may affect puberty timing?
Mutations in KISS1R affect puberty timing, implicating Kisspeptin-KISS1R signalling in regulation of this process.
Compliance with the predictable sequence of developmental events is called?
Consonance
What is development?
Global impression of a child - increase in understanding, acquisition of new skills and more sophisticated responses and behaviours
What are the four domains of child development?
Speech and language skills, social skills, gross motor skills and fine motor skills