postnatal and child development Flashcards
genetic Transition from prenatal to postnatal growth
pre
–Minor effect overall
-Maternal size determining birth size
-Paternal genetic factors have little effect on birth
-Maternal factors tend to override fetal genetic factors in determining prenatal growth
post
-Largely determines final adult height
-Sex chromosomes have an effect:
-XY boys are taller than XX girls
endocrine Transition from prenatal to postnatal growth
pre
-Insulin and (IGFs) are major prenatal hormones influencing growth:
-IGF-2= embryonic growth
-IGF-1=later fetal and infant growth
-(Growth hormone has no effect on early growth)
post
-Human growth hormone (hGH) is the major hormone controlling growth after birth
nutrition Transition from prenatal to postnatal growth
pre
-Placenta provides all nutrients and controls hormones-essential for growth
-Placental insufficiency most common cause of IUGR
-Maternal diet influences nutritional availability
post
-Adequate nutrition is essential for growth- Starvation/malabsorption of nutrients limit growth potential
-Obesity-excessive intake of food
-Poor nutrition delay puberty onset.
environment Transition from prenatal to postnatal growth
pre-
-Uterine capacity and placental sufficiency important in providing optimal environment for fetus
-placental function more influential than uterine capacity
post
-Socioeconomic status
-Chronic disease
-Emotional status
-Altitude (mediated by lower oxygen saturation levels)
postnatal growth - what are the 4 phases
Fetal
Infantile
Childhood
Pubertal
when does the crainial suture close by
18 months
Phases of growth: fetal phase
-fastest growth
-30% of height
-Growth= hyperplasia during fetal life:
a) 42 cycles of cell division before birth,
b) 5 cycles of cell division from birth to adulthood.
domains of growth: infantile phase
0-18 months
-15% of height.
-Rapid, but decelerating growth
Length increases by 50%, head circumference by 30% and weight triples vs birth
-Growth nutrition dependent
phases of growth- childhood phase
18m -12y.o
40% of height.
Steady, slow growth
5-6 cm annual increase in height, and 3-3.5kg annual increase in weight
-endocrine growth regulation increasing
phase of growth: pubertal phase
pubertal growth spurt
15% of height.
increasing sex hormones boost 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
when does mini puberty and normal puberty occur and the purpose - brief
mini- neonate. Priming of HPG axis
normal-adolescence. sexual maturation
when does Gonadotrophin starts secreting?
what is mini puberty and how it starts? when does mini puberty ends?
-Gonadotrophin secretion starts at end of the first trimester, peaks mid-pregnancy, then declines
-HPG axis is transiently activated after birth (mini-puberty), after release from placental hormones restraint
-Continues for 6 months after birth before declining
point of mini-puberty?
-Elevated sex steroids in males during mini-puberty seems to be important for normal gonadal development
-Role of minipuberty less clear in female infants.
-Estradiol levels fluctuate through first few months after birth.
-Follicular develop in ovary.
-development of mammary tissue?
-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 compared to girls.
what triggers puberty (onset)
unclear,
influenced by metabolic status
neurokinin KNDy neurons-> regulate release of Kisspeptin peptides->
act on GnRH neurons to promote pulsatile GnRH release
Mutations in KISS1R affect puberty timing, implicating Kisspeptin-KISS1R signalling in regulation of this process.
The developmental events of puberty typically follow a predictable pattern
-what is it called?
consonance
