Problems in Pregnancy: Small for Dates Flashcards
Reasons for small baby
Pre term delivery
Small for gestational age
- IUGR/FGR
- Constitutionally small
What is preterm delivery?
Delivery before 37 weeks gestation
Extreme preterm: 24 – 27+6 weeks
Very preterm: 28 – 31+6 weeks
Moderate to late preterm: 32 – 36+6 weeks
Why is preterm birth important?
Survival and long term outcome
Beynd 32 weeks >95% survival
Aetiology of preterm birth
Infection ‘Over distension’: - Multiple - Polyhydramnios Vascular: - Placental abruption - Intercurrent illness: - Pyelonephritis / UTI Appendicitis Pneumonia Cervical incompetence Idiopathic
Risk factors for preterm birth
Previous PTL (20% risk X1; 40% X2)) Multiple (50% risk) Uterine anomalies Age (teenagers) Parity (=0 or >5) Ethnicity Poor socio-economic status Smoking Drugs (especially cocaine) Low BMI (<20)
Define Small for gestational age (SGA) fetus
Estimated fetal weight or abdominal circumference below the 10th centile
- Population centiles
- Customised centiles
IUGR/FGR = failure to achieve growth potential LBW = birth weight below 2.5 kg (regardless of gestation)
Types of IUGR
symm: head and abdomen in proportion (chromosomal abnormality
Assymm: head > abnormal (placental pathology)
How to identify SGA fetus?
Antenatal risk factors
Screening during antenatal care
Minor antenatal risk factors of SGA
Maternal age >35 years IVF pregnancy Nulliparity BMI <20 BMI 25-34.9 Smoker 1-10 cigarettes/day Low fruit pre-pregnancy Previous pre-eclampsia Pregnancy interval <6 months Pregnancy interval >60 months
Major antenatal risk factors of SGA
Maternal age >40 years Smoker >11 cigarettes/day Paternal SGA Cocaine use Daily vigorous exercise Previous SGA baby Previous stillbirth Maternal SGA Chronic hypertension Diabetes with vascular disease Renal impairment Antiphospholipid syndrome Heavy bleeding in pregnancy Low PAPP-A Fetal echogenic bowel BMI >35 Known large fibroids
Screening during antenatal care
all low risk pregnant women should have symphysial fundal height measured regularly from 24 weeks.
- Growth scan if single measurement below 10th centile on customised chart
- Serial measurements suggest slow/static growth
Diagnosis of SGA
Measurement of fetal AC
Combine with head circumference +/- femur length to give EFW
Additional information: liquor volume or amniotic fluid index and Dopplers
Maternal factors causing SGA
Lifestyle: - Smoking - Alcohol - Drugs Height and weight: smaller mothers more likely to have smaller baby Age Maternal disease e.g. hypertension
Uterine artery dopplers and SGA babies
At the 20 weeks scans all women will have the resistance of uterine arteries measured
At this time placenta should be well established and good forward flow of blood to placenta
If resistance is found in both uterine arteries - high risk of SGA and HTN in pregnancy
- most likely due to abnormal placentation, so failure of spiral artery invasion
Placental Factors causing SGA
Infarcts
Abruption
Often secondary to hypertension
Fetal Factors causing SGA
Infection e.g. rubella, CMV, toxoplasma
Congenital anomalies e.g. absent kidneys
Chromosomal abnormalities e.g. Down’s syndrome
Antenatal Consequences of IUGR
risk of hypoxia and/or death
Postnatal consequences of IUGR
Hypoglycaemia Effects of asphyxia Hypothermia Polycythaemia Hyperbilirubinaemia Abnormal neurodevelopment
Presentation of poor growth
Predisposing factors
Fundal height less than expected
Reduced liquor
Reduced fetal movements
Assessing foetal wellbeing
Assessment of growth
Cardiotocography
Biophysical assessment
Doppler US
+/- CTG
Umbilical artery doppler - idea of what the pressure and resistance is of flow from placenta to baby
MCA and ductus venosus doppler - increased risk of still birth
Indications for early delivery by C-sec
Growth becomes static (IOL may be appropriate)
Abnormal umbilical artery Doppler
Normal umbilical artery Doppler with abnormal MCA between 32 and 37 weeks
Abnormal umbilical artery Doppler with abnormal ductus venosus Doppler between 24-32 weeks
Consider the following when planning delivery
Steroids
MgSO4
