Low birth weight and prematurity Flashcards
What is the difference between small for gestational age (SGA) and intrauterine growth restriction (IUGR)?
Small for gestational age simply means that the baby is small for the dates, without stating why. The fetus may be constitutionally small, growing appropriately, and not at increased risk of complications
IUGR: when there is a small fetus (or a fetus that is not growing as expected) due to a pathology reducing the amount of nutrients and oxygen being delivered to the fetus through the placenta.
What is normal weight range of baby? [1]
What is LBW range? [1]
What is VLBW? [1]
What is Exremely Low? [1]
Low birth weight (LBW) = 2,499g or less regardless of gestational age
Sub-category very low birth weight (VLBW) = less than 1,500g
Sub-category extremely low birth weight (ELBW) less than 1,000g
Normal weight at term 2,500-4,200g
What defines a baby as having Intrauterine growth restriction (IUGR)? [3]
Fetus with birth weight less than 10th percentile of those born at same gestational age
Two standard deviations below population mean are considered growth restricted
IUGR should strictly refer to fetus that is small for gestational age and that displays other signs of chronic hypoxia or failure to thrive
What are the 3 overiding factors that caues IUGR? [3]
Maternal factors (age / nutrition / stress / genotype / previous IUGR / HTN / substance abuse)
Placental and cord abnormalities (placental insuffiency - reduced AA transport, O2 delivery /; placental tumour / single umbilical artery / incorrect cord insertion)
Foetal factors (Congential heart disease / downs, turners, pataus syndrome)
Normal fetal growth is characterised by cellular [] followed by [] and [] and finally [] alone
Normal fetal growth is characterised by cellular hyperplasia followed by hyperplasia and hypertrophy and finally hypertrophy alone
Growth rate of normal fetus: Weight gain is:
[] per day at 14-15 weeks of gestation
[] per day at 20 weeks
[] per day at 32-34 weeks
Then growth rate decrease
Weight gain
5g per day at 14-15 weeks of gestation
10g per day at 20 weeks
30-35g per day at 32-34 weeks
Then growth rate decrease
Which maternal mesaurement (height) height approx increases at 1cm per week between 14 and 32 weeks? [1]
How does abdominal girth change after 30 weeks, per week? [1]
Symphysiofundal height increases approx 1cm per week between 14 and 32 weeks
BUT if have polyhydramnios then this would cause inaccurate readings
After 30 weeks - increases by 2.5 cm per week
After how many weeks does foetus growth rate decrease? [1]
at 32-34 weeks
Explain the pathology behind Type 1 IUGR:
- Is it caused by problem with mother or fetus? [1]
- Is it symmetrical or asymmetrical? [1]
- Between which weeks during pregnancy does it normally occur? [1]
Type 1 IUGR:
- Problem with fetus growth during week 4-20 (when most of mitosis is occuring)
- Everything is symmetrical / normal ration: but all parameters are below 10th percentile for gestational age
How would you detect infection in placenta histologically? [1]
Presence of lymphocytes or plasma cells
Mother should be transferring antibodies, not lymphocytes into the placenta
What are causes of type 1 IUGR? [4]
Etiology:
* Genetic
* Infection (intrinsic to fetus)
* Multiple gestation
* Environmental toxins
- Explain pathophysiology of Type 2 IUGR [1] Which maternal pathologies is it associated with? [3]
- When does in pregnancy does it usually occur? [1]
- How do neonates appear? [1]
- WHat do neonates have reduced growth in? [2]
- Caused by uteroplacental insufficiency: uterus not providing enough nutrition for fetus. Associated with: maternal HTN / pre-eclampsia; renal disease; vasculapathies
- Growth restriction begins after week 28 in stage of hypertrophy : Fetus has near normal cell number but size reduced
- Asymmetry seen: head sized normal, but redistribution of fetal CO causes reduced abdomen and splachnic growth, whilst brain is spared.
Mothers more at risk of giving birth to a IUGR baby have what wrong with them? [5]
Poor maternal nutrition: Low BMI at conception; Poor maternal weight gain during pregnancy
Pre-eclampsia
Renal disorders
Diseases causing vascular insufficiency
Infections (TORCH)
What type of histocytes normally prevent vertical transmission of disease? [1]
Macrophages (histocytes) called Hofbauer cells prevent vertical transmission. Shouldn’t be found in choroinic villi
What complications of IUGR would you expect in antepartum period? [2]
- Increased incidence of still births (52% of unexplained still births – die in utero)
- Oligohydramnios (esp. type 2 - kidneys haven’t formed properly)
What pathology is 4-6 x higher of occuring in childhood because of IUGR? [1]
Cerebral palsy
What complications of IUGR would you expect in intrapartum period? [2]
Higher incidence of meconium aspiration:: Fetal distress
Intrapartum fetal death
What complications of IUGR would you expect in neonatal period? [5]
- Increased incidence of hypoxic ischemic encephalopathy: heart not developed so o2 to brain is insufficient
- Persistent fetal circulation insufficiency (patent ductus arteriosus - all O2 blood is mixed with deO2 - leads to hypoxia)
- Difficulty in temperature regulation: Absent brown fat and small body mass to surface area in type 2
- Poor glycogen stores may predispose to hypoglycemia
- Chronic intrauterine hypoxia lead to polycythemia, necrotizing enterocolitis, other metabolic abnormalities
What measurement would use clinically to diagnosis IUGR? [1]
What is normal growth of ^? [1]
What would indicate IUGR? [1]
What would indicate severe IGR? [1]
Symphysio-fundal height:
- Lag in fundal height of 4 weeks suggestive of IUGR
- Lag of >6 weeks is suggestive of severe IUGR
Which mothers at more risk of givng birth of IUGR babies? [5]
- Poor maternal nutrition (low BMI at conception; underweight / overweight)
- Pre-eclampsia
- Renal problem
- Vascular insufficiency
- TORCH infections
Using a ultrasound to diagnose IUGR, what would you investigate? [3]
Head circumference
Abdominal circumference (AC) - AC highest sensitivity and greatest predictive value for diagnosis of IUGR
Amntiotic fluid volume
Can assess if type 1 or 2 by assessing differences in head vs abdomen
Say you had identified IUGR using fundal-height. What investigation amay you do next to diagnose IUGR? [2]
Ultrasound [1]
Doppler ultrasound [1]
Fundal height is a measure between which two points? [2]
Fundal height: Pubic symphysis to top of where can palpate uterus / fundus Exam Q!
Type [] IUGR associated with oligohydramnios
Type 2 IUGR associated with oligohydramnios - due to reduced kindey function
What is difference between pre-term and premature?
Pre-term: < 37 weeks
Nutrition:
Ensuring that pregnant mother consumes which vitamin reduces the incidence of pre-term by 60%? [1]
Vitamin D level of mother of >40ng/ml reduces incidence of pre-term birth by 60%
Deficiency of 25(OH)D also increases morbidity and complications in preterm infants
Explain the pathology that associated with lungs with pre-term birth? [5]
Respiratory distress syndrome
Hyaline membrane (fibrotic tissue) develops
Surfactant deficiency
Type II pneumonocytes
Results in decreased lung compliance, unstable alveoli
What is intraventricular hemorrhage of new born?
Blood vessels in preterm may be more fragile and immature
Occurs within first 4 days
For Type 1 & Type 2 IUGR, state if:
Cell number: Normal or Reduced? [2]
Cell size: Normal or Reduced? [2]
Type 1 IUGR:
* Cell number: reduced
* Cell size: normal
Type 2 IUGR:
* Cell number: normal
* Cell size: reduced
Which type of IUGR does this baby display? [1]
asymmetrical IUGR
Note loss of fat whole over the body, visible rib cage, excessive skin fold whole over the body and relatively large heads compared with rest of the body.
What are for maternal pathologies that can cause type 2 IUGR? [4]
Caused by uteroplacental insufficiency: uterus not providing enough nutrition for fetus. Associated with: maternal HTN / pre-eclampsia; renal disease; vasculapathies
