Fetal growth Flashcards
how do you assess how well the baby is growing?
palpate, look, measure (fundus to pubic symphsis)
the palpation of the abdomen is the simplest way to determine the size of the infant- gives you the symphysis fundal height
What is the SFH?
symphysis fundal height.
distance over the abdominal wall from the symphsis to the top of the fundus.
It may be small - they may have the dates wrong, small baby, transverse lie, little fluid. OR the baby is small for the gestational age.
Larger - wrong dates, multiple pregnancies or obesity.
GOOD: as it is inexpensive and simple BUT low detection rate as has many counfounders
What is used to measure the baby now?
Ultrasound. After 14 weeks
TAKE: BDP(biparietal diameter), HC(head circumference),AC (abdominal circumference),FL (femur length)- give you the approximate weight
Look at graphs and be worried if it crosses percentiles
ULTRASOUND IS USED TO DATE USING THE CROWN RUMP SIZE AT THE END OF THE FIRST TRIMESTER AS THIS IS WHEN GROWTH IS AT ITS SLOWEST.
Why is it important to accuratley date?
SGA or LGA confusion
inappropraite inductions
steroids in preterm delivery.
What maternal factors affect fetal growth?
Maternal- poverty (less nutrition and education)
age (over 35 = longer labour period and more likely to have complications but younger are more likely to drink and smoke)
drug use(metabolised by the placenta and transmitted to the fetus leading to a greater chance of birth defects, low birth weight and still births)
Alcohol (disruptions in the fetus’ brain + cell development and maturation + CNS maturation)
smoking - nicotine = less blood flow to the fetus , Co reduces the o2 and this can lead to still birth, low birth weight and ectopic pregnancy.
diseases - placenta may not filter out so can inherit this.
diet + physical health - needs adequate nutrition. low iron = anaemia + low calcium = weak bones
prenatal depression - slower fetal growth
environmental toxins - miscarriage, sterility, birth defects.
What fetal hormones are important?
Somatotrophin insulin prolactin FSH/LH etc
Can there be a customised growth chart?
can adjust for maternal height, weight and ethnicity.
What is SGA(small gestational age)?
birth weight less than the tenth percentile
What is IUGR?
failure of the infant to reach it’s predetermined potential due to a variety of reasons.
this is one of the most common identifiable factors in still births.
Why does LBW matter?
not always growth restricted
this is less than 2.5kg at birth. only 7% of live births.
very LBW - less than 1.5kg
extremely LBW - less than 1kg
IMPORTANT AS THOSE WITH A LOW BIRTH WEIGHT ARE AT RISK OF A RANGE OF NEONATAL COMPLICATIONS + COMMODITIES AND MORTALITY (CHD, IHD AND DIABETES)
what are the short and long term sequelae of FGR?
most common for still born babies
resp distress - minimised with steroid injections to the mum
haemorrhage
sepsis
jaundice
electrolyte imbalance
hypoglycaemia
long term issues of fetal programming
What are causes of SGA?
dating problem
normal
fetal problem (5%)- infection or abnormality(chromsomal)
placental insufficency (20%) - reduction in AC/FL, reduced liquor (amniotic fluid), derange dopplers
Why is the placenta?
maintains immunological distance between mum and fetus.
What are concerns in the index pregnancy?
abnormal serum biochemistry reduced symphysis fundal height maternal systemic disease coagulation anterpartum haemorrhage
How can FGR be predicted?
through a good history
What is pre-eclampsia?
Multisystem disease that usually manifests as hypertension and proteinuria
what is the definition of fetal growth?
the increase in mass that occurs between the end of the embryonic period and birth.
how does the fetal weight and length change over the course of the pregnancy?
weight should continually increase where the length has less change in later stages.
how is fetal growth monitored?
using the parameters from the ultrasound the fetus should remain along the same centile- allows accomodation for larger or smaller infants.
when does normal fetal growth rate decrease?
after 34 weeks.
what is normal fetal growth characterised by?
cellular hyperplasia - 4-20 weeks (increased cell numbers)
hyperplasia and hypertrophy - 20-28 weeks (this is an increase in cell number and size)
Hypertrophy predominates - 28-40 weeks
what are the counfounding factors in dating pregnancy?
this usually uses the date from the last menustral cycle.
this can vary due to:
irregular length of periods, use of oral contraceptives, breastfeeding, abnormal endometrial bleeding.
how is a more accurate gestational age determined?
this is using the crown rump size in an ultrasound.
Ideally at the end of the first trimester as this is when growth is limited.
what fetal-placental factors influence the fetal growth?
gender- males tend to be bigger .
previous pregnancies - infants get heavier with subsequent pregnancies.
hormones- insulin is needed for insulin-like growth factors. cortisol - alters transcription and may lead to switvh from IGII (early embryonic)to IGFI(growth of the newborn). thyroxine for tissue differentiation.
What are the causes of IUGR to do with the mother?
usually in the second and third trimester of pregnancy
Maternal medical factors: Chronic hypertension Severe chronic infection Diabetes mellitus Anaemia Uterine abnormalities Maternal malignancy Pre-eclampsia
Maternal behavioural factors Smoking Low booking weight (<50 kg) Poor nutrition Age <16 or >35 years at delivery Alcohol Drugs High altitude Social deprivation
what are the causes of IUGR to do with the fetus?
Multiple pregnancy Structural abnormality Chromosomal abnormalities Intrauterine (congenital) infection Inborn errors of metabolism
what are the placental factors that lead to IUGR?
Impaired trophoblast invasion Partial abruption or infarction Chorioamnionitis Placental cysts Placenta praevia.
why does IUGR and pre-ecamplsia occur together?
main cause of pre-eclampsia is the diminished remodelling of the spiral arteries by cytotrophoblasts.
This leads to decrease blood flow and nutrient supply to the fetus.
what is the management of IUGR and pre-eclampsia?
timing the delivery of these pregnancies.
corticosteroids at gestation.
what does fetal growth depend on?
Genetic potential
derived from both parents mediated through growth factors eg insulin like growth factors
Substrate supply
essential to achieve genetic potential
derived from placenta which is dependent upon both uterine and placental vascularity
