Foetal Growth Flashcards

Question

What are the causes of SGA?

Answer 1

Most small for gestational age babies are normal - but may just be constitutionally small. 20% due to placental insufficiency - Inadequate nutrients provided (Nutrients will be diverted and abnormal foetal dopplers will be observed) 5% due to foetal problem - This could be a chromosomal abnormality

Answer 2

10-12 weeks is the period of placentation Rapid early growth prepares way for foetal growth Trophoblast cells use same molecular mechanisms as tumors, but are highly regulated and controlled The placenta maintains immunological distance between mother and foetus Special endocrine organ: produces protein-peptides and steroid hormones It functions as a “transient hypothalamo-pituitary-gonadal axis” Responsible for exchange of nutrients, gases & waste products between maternal and fetal circulation

Answer 3

In a non-pregnant woman, the placenta looks different. The spiral arteries in non-pregnant state sit within the endometrium. In normotensive, normal pregnancy, the spiral arteries open up. There is a wave of trophoblastic invasion. Trophoblasts invade, to get rid of the muscular wall. There is a funnel shapes, much more dilated vessel, to accommodate the increased amount of blood flow from mother to baby. In pre-eclamptic toxaemia, the process of trophoblastic invasion failed. The spiral arteries remain narrow. There is a high shearing force just to get through to the blood supply. This causes ischaemic changes and endothelial imbalance

Answer 4

PET (Pre-eclampsia toxaemia) is associated with LBW/FGR. Defined as pregnant women who have hypertension, oedema and proteinuria. Maternal compensatory effects (mother has hypertension to compensate for blood supply) This is extremely common – there is HBP in 10% of all pregnancies (1-2% suffer a severe form). Arises de novo. It occurs after the 20th week of gestation in a previously normotensive woman and resolving completely by the 6th postpartum week. Foetal syndrome (FGR without pre-eclampsia) is relatively rare.

Answer 5

BP>140/90mmHg and proteinuria >0.3g/24hour (PCR>30) Mild: 140-149/90-99mmHg Moderate: 150-159/100-109mmHg Severe: ≥160/110mmHg

Answer 6

``` Bad Obstetric History Previous maternal hypertension Previous FGR Stillbirth Placental Abruption ``` ``` Concerns in index pregnancy Abnormal serum biochemistry Reduced symphysis fundal height Maternal systemic disease e.g. hypertension, renal, coagulation Antepartum haemorrhage ```

Answer 7

PAPP-A < 0.4 MoM (one of the things we can screen for Down’s syndrome with), POHx PET/FGR Maternal systemic disease e.g. HT, renal, sickle Uterine artery Doppler 1st/2nd trimester – blood flow through uterine arteries (This allows us to identify high resistance flow- indicates a higher increase in resistance in the maternal circulation)

Answer 8

``` Poor Obstetric History Primips (first pregnancy) Obese Afro-Caribbean / African Strong Family History Essential hypertension Diabetes / Impaired Glucose Tolerance Systemic vascular disease Renal disease Thrombophilias ```

Answer 9

Normal maternal circulation - high shearing forces at placenta. If placenta fails, higher resistance within the umbilical artery. The baby begins to stop growing, causing reduction in foetal movements. Baby tries to compensate - diverts blood to the vital organs. Shuts down supply to the kidneys, resulting in less amniotic fluid. Causes decompensation. Needs immediate delivery to prevent intrauterine death.

Answer 10

Doppler ultrasound techniques looks at different arteries. Umbilical arteries give idea of placental blood flow. Increased impedance becomes evident only when at least 60% of the placental vascular bed is obliterated. As the baby becomes more hypoxic, there is high resistance to virtually no end diastolic flow. Reversible flow results as the baby becomes more acidotic. The baby also slows down movements. Eventually, we see heart range changes on the CTG. As the baby becomes more hypoxic, there is lower resistance to blood flow in the brain (e.g. middle cerebral artery).

Answer 11

The umbilical vein diverts 25% of its flow to the ductus venosus. As the baby becomes more and more hypoxic, it goes from a normal, low resistant pattern to a HIGH resistance pattern

Answer 12

A reduction in foetal movements may precede foetal death by a day or more Cardiff kick chart is the most commonly used method UK. Mothers record time to feel ten foetal movements daily Reduction (or absence) in foetal movements, requires cardiotocography and/or an ultrasound assessment of the foetus to ensure foetal wellbeing. Foetal heart rate monitored using CTG.

Answer 13

Timing delivery in these pregnancies depends on balancing the risks to the foetus if it remains in utero and the hazards from the prematurity, which decrease as the gestation advances Evidence of foetal compromise on CTGs or abnormal Dopplers/ultrasound finding/maternal compromise Corticosteroids should be administered (if not already given) at gestations < 36 weeks in order to improve neonatal wellbeing (Labour may be poorly tolerated due to cord compression)

Answer 14

Early IUGR: This has a low incidence (1%) Highly correlated to maternal disease (pre-eclampsia) Difficult to manage: balancing risks of severe prematurity and morbidity with risk of in utero death ``` Late IUGR: More common (5-7%) Rarely correlated to pre-eclampsia Difficult to differentiate from constitutionally SGA Easy to manage: deliver ```