Lecture 13 – Fetal Growth Flashcards
What are the three phases of fetal development and growth?
First - 4-20 weeks - cellular hyperplasia in which there are increases in fetal weight, protein and DNA content
Second - 20-28 weeks - hyperplasia and commitant hypertrophy, increases in fetal weight and protein but less DNA increase.
Third - 28 weeks to term - hypertrophy - continued increases in hypertrophy and weight but no DNA increase
What are the terms IUGR, LBW, SGA and LGA?
IUGR - intrauterine growth restriction - failure for a fetus to reach his/her growth potential
LBW - low birth weight - birth weight below a preset level e.g. 2500g
SGA - small for gestational age - birth weight less than the 10th centile for gestational age.
LGA - large for gestational age - birth weight greater than 10th centile for gestational age.
What is the fundal height?
It is the distance from the pubic bone to the top of the uterus. Can be used to roughly measure fetal growth.
What are the consequences of fetal growth restriction?
More likely to die within first year.
More likely to suffer from neonatal problems.
IUGR can have lifelong consequences.
What is the barker hypothesis of children with fetal growth problems?
Most catch up in childhood but will have a smaller adult size.
What is a ‘thrifty phenotype’ programming?
evolved to offer an advantage to babies in famin taking advantage of all nutrients they can get. Not advantageous in industrialised society.
What is the result of mothers who were small for gestational age?
They are more likely to have babies that are small for gestational age.
What are the mechanisms for intergenerational effects of fetal growth problems?
Epigenetics - cause heritable changes in the DNA expression that is not changes in the DNA itself
Maternal mitochondria - can change in number depending on food restriction
What are the causes of LGA?
Biggest cause is maternal diabetes Being born late Mother being obese Boy babies more likely than girls Multiparity (more than one child)
This is due to increased glucose concentrations and fetal growth factors.
What are the maternal factors that effect fetal growth?
Ethnicity Nutrition Drugs e.g. alcohol and smoking BMI Maternal hypoxia
What was found out by the 1940 dutch famine?
That if mothers were malnourished towards end of pregnancy then the babies will be growth restricted.
If the mothers were malnourished at the start of pregnancy then have normal birth weight but more likely to have growth restricted babies when give birth as adult.
What are the fetal factors that affect fetal growth?
Chromosomal disorders
Growth factors
Congenital infection
What is the difference between primary placental and secondary placental problems?
Primary - abnormal placental structure
Secondary - Hypertension, chronic renal disease etc.
What is the result of poor trophoblast invasion of the maternal spiral arteries?
Results in poor placental perfusion. Should have occured at 20-24 weeks
Why do hypothyroid mothers often produce smaller babies?
There are less growth factors from the thyroxine.
