Fetal Growth - Types and Problems Flashcards
What are the four types of fetal growth?
1) AGA - appropriate for gestational age
2) SGA - small for gestational age
3) FGR/IUGR - fetal growth restriction
4) LGA - large for gestational age
What is FGR?
- Starved baby
- Inconsistent growth
When are we not concerned about a SGA baby/healthy small baby?
- If growing consistently at 10% centile, just a small baby
- Constitutionally small
- Small parents
What are causes of an intrinsically small SGA baby?
1) Chromosomal abnormality e.g. T21, T18, T13
2) Infectious e.g. CMV
3) Environmental e.g. fetal alcohol syndrome
What are the 3 types of SGA baby?
1) Intrinsically small
2) Growth-restricted small
3) Healthy small
What are the causes of a growth-restricted small SGA baby (FGR/IUGR)?
1) Insufficient nutrient delivery gas exchange (placenta)
2) Maternal vascular disease e.g. HT, PET, DM
3) Maternal decrease O2 capacity e.g. sickle cell
4) Placental damage e.g. smoking
What are the 3 types of causes of IUGR?
1) Mother - chronic illness, smoking, drugs, alcohol
2) Placenta - pre-eclampsia
3) Baby - congenital abnormality
What is the definition of a SGA infant?
Birth weight < 10th centile
What is the definition of a SGA fetus?
EFW or AC < 10th centile
What is severe SGA?
- Fetus EFW or AC < 3rd centile
- Higher chance of FGR
What is FGR/IUGR?
- SGA baby with evidence of compromise e.g. amniotic fluid or changes with doppler
- Pathological restriction of genetic growth potential
- May have evidence of fetal compromise e.g. abnormal AFI or dopplers
- Has increased risk of perinatal complications
What perinatal complications are FGR babies at increased risk of?
1) Stillbirth
2) Seizures
3) Apgar score < 4 - poor prognosis sign
4) Cord pH < 7.0
5) Admission to intensive care
6) Hypothermia
7) Hypoglycaemia
What is the Apgar score and when is it given?
- Test given to newborns soon after birth which checks a baby’s heart rate, muscle tone, and other signs to see if extra medical care or emergency care is needed
- At 1 minute, 5 minute and 10 minute after birth
- < 4 is a poor prognosis sign
What are the perinatal outcomes of SGA babies?
Similar to AGA babies
What might FGR babies benefit from?
Being delivered early
What are long term consequences of FGR?
- Coronary heart disease
- Cerebrovascular accident (CVA) = stroke
- T2D
- Hypertension
How does the NHS aim to halve the rate of stillbirth?
1) Reducing smoking in pregnancy
2) Risk assessment and surveillance for fetal growth restriction
3) Raising awareness of reduced fetal movement
4) Effective fetal monitoring during labour
What are risk factors for an SGA fetus?
1) Current/demographic risks
2) Previous pregnancy risks
3) Maternal medical history
4) Current pregnancy complications
Is SGA fetus screened for?
Yes (look at diagram in notes if want to know more)
What is PAPP-A?
- Pregnancy associated plasma protein A
- Assessed as part of the firs trimester combined screen
What do low levels of PAPP-A indicate?
- Associated with poor placentation - poor implantation or formation
- Low PAPP-A (<0.4MoM) means there is an increased risk of SGA/pre-eclampsia (PET)
How would you manage a patient with PAPP-A < 0.4?
1) Give aspirin 75mg once a day
2) Arrange growth scans e.g. at 26-28 weeks and 34-36 weeks
What is a uterine artery doppler?
- Maternal artery measurement
- Can be done in 1st trimester or 20-24 weeks
What do uterine artery doppler results indicate?
- Low resistance to flow is reassuring (not peaks)
- High resistance to flow at 24 weeks = PI > 1.4 - increased risk of SGA/PET
- High peaks = high resistance flow, indicating redistribution of blood e.g. to brain
How would you manage a patient with uterine artery doppler at 24 weeks PI > 1.4?
Arrange growth scans e.g. 26-28 weeks and 34-36 weeks
What are maternal factors (diseases) that lead to increased risk of SGA (high risk pregnancies)?
1) Diabetes (also LGA)
2) Hypertension/pre-eclampsia
3) Active lupus
4) Sickle cell disease
What are fetal factors that lead to increased risk of SGA (high risk pregnancies)?
1) Multiple pregnancies
2) Fetal structural abnormality
3) Fetal chromosomal abnormality
4) Fetal infection
What are the options for twin growth?
1) Both grow normally
2) Both SGA
3) One normal, one FGR
Why is it easier if both twins are small?
Makes the decision easier as can take both out early if need to
Which type of twins have a higher risk of growth problems?
Monochorionic
What is the difference between monochorionic and dichorionic twins?
Monochorionic = one shared placenta Dichorionic = two placentae, one for each twin
How do you manage dichorionic twin pregnancy?
- Lower risk of problems
- Scan every 4 weeks to keep an eye on growth, amniotic fluid and uterine artery doppler
How do you manage monochorionic twin pregnancy?
- Higher risk of problems
- Scan every 2 weeks
What are three possible problems that can occur in a monochorionic twin pregnancy leading to growth problems?
1) Selective IUGR - unequal sharing of placenta supply
2) Twin-to-twin transfusion - vessels that connect with priority of flow in one direction making one twin the donor and the other the recipient, one twin gets more blood and nutrients than the other
3) TAPS (twin anaemia polycythaemia sequence)
- Rare condition that occurs when there are unequal blood counts between the twins in the womb
- Unequal blood counts cause the twins to suffer from an imbalance in red blood cells and haemoglobin
- This means one twin is not receiving the appropriate amount of oxygen and nutrients it needs to develop properly
What are the principles of SGA pregnancy management?
1) Screen and identify at risk pregnancies - aspirin in low PAPP-A/risk of PET, uterine artery dopplers
2) Monitor scans if at risk
How do you manage a baby with abnormal growth?
Increase frequency of scans, measure growth every 2 weeks (need time to grow)
When would you deliver a baby with FGR/functional concerns (abnormal doppler)?
Consider early delivery (steroids for lung)
When would you deliver a SGA baby?
Consider induction at 37 weeks (term)
When is LGA used and when is macrosomia used?
LGA = fetus Macrosomia = baby
What is the definition of large for gestational age (LGA)?
EFW > 90th centile
What is the definition of macrosomia?
Birth weight > 4kg (approx 10% of babies)
What are the risk factors/causes for an LGA baby?
1) Constitutional (large/tall parents)
2) Raised BMI - BMI 25-30 = 1.5x risk, BMI > 30 = 2x risk
3) Previous LGA baby
4) Diabetes - type 1, type 2, gestational
What is normal LGA fetal growth?
Being consistently above the 90th centile
What is abnormal LGA fetal growth and what could cause this?
- Normal growth e.g. on 50th centile and then sudden jump on next growth measurement to above 90th centile
- Could occur following maternal development of gestational diabetes or due to polyhydramnios (AFI > 24cm)
What can reduce the chance of an LGA baby?
Diagnosing and managing diabetes in pregnancy
When should testing for gestational diabetes be offered (diabetic screening)?
1) BMI > 30
2) Previous macrosomic baby weight ≥ 4.5kg
3) Previous gestational diabetes
4) FH of diabetes (first-degree relative)
5) Minority ethnic family origin with high prevalence of diabetes
What are the potential perinatal complications to an LGA baby?
1) Shoulder dystocia
2) Hypoglycaemia if diabetic pregnancy
What is shoulder dystocia and its complications?
- Anterior shoulder can get stuck on the pelvis
- Head is out
- Obstetric emergency
- Bone on bone
- Can lead to brachial plexus nerve injury where can’t use muscle in hand - 10% terminal. 90% will resolve
- Can lead to fractured humerus/clavicle - can be deliberate if shoulder dystocia is really bad
- Birth asphyxia/stillbirth
What are the maternal complications of an LGA baby/what are the mothers at increased risk of with an LGA baby?
1) C section/instrumental birth e.g. suction cups or forceps
2) Perineal trauma/tears if vaginal birth - around anal area, 3rd degree tears
3) Postpartum haemorrhage
When would you offer an elective C section with an LGA baby?
1) EFW > 4.5kg in diabetic pregnancy
2) EFW > 5kg in non-diabetic pregnancy
- EFW can be out by 10-15% or extremes (big or small babies) at 20-25%
- Talk about risks and benefits
What can pregnancy be an insight into?
Future health issues for women
Describe macrosomia
- Increasingly common
- Associated with maternal obesity and diabetes
- Causes problems in labour - increased risk of still birth, C section often needed
