Antenatal Care Flashcards by S V

What is small for gestational age?

An infant with a birth weight <10th centile for its gestational age
Severe SGA is a birth weight < 3rd centile

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What is foetal small for gestational age?

An estimated foetal weight/abdominal circumference < 10th centile
(Severe < 3rd centile)

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What is foetal growth restriction?

A pathological process restricting growth potential
Can present with features of foetal compromise including reduced liquor volume or abnormal Doppler studies
The link to FGR is greater in severe SGA foetus

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What does low birth weight refer to?

An infant with a birthweight less than 2500g

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What are the causes of a small for gestational age baby?

Normal (constitutionally small)
- small size at all stages of growth 
- no pathology present
- factors - ethnicity, sex, parental height 
Placenta mediated growth restriction
- normal initially, but slows in utero
- common cause of FGR
- maternal factors result in placental insufficiency
Non placenta mediated growth restriction
- growth affected by foetal factors

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What are the maternal factor that can cause foetal insufficiency?

Low pre-pregnancy weight
Substance abuse
Autoimmune disease
Renal disease
Diabetes
Chronic hypertension

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What are the foetal factors that can cause non-placenta mediated growth restriction?

Chromosomal/structural anomalies
Error in metabolism
Foetal infection

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What are the minor risk factors for SGA?

Maternal age >/= 35
Smoking 1-10 a day
Nulliparity
BMI <20/25-34.9
IVF singleton
Previous pre-eclampsia
Pregnancy interval <6 or 60 months +
Low fruit intake pre-pregnancy

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What are the major risk factors of SGA?

Maternal age over 40
Smoking 11+/day
Previous SGA baby
Maternal/paternal SGA
Previous stillbirth
Cocaine use
Daily vigorous exercise
Maternal disease (chronic HTN, renal impairment, diabetes with vascular disease, antiphospholipid syndrome)
Heavy bleeding
Low PAPP-A

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When are the risk factors for SGA checked?

At booking

Again at 20 weeks gestation

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Describe the diagnosis and clinical features of an SGA baby.

USS - diagnosis and surveillance - EFW, AC - plotted on customised centile charts taking into account maternal characteristics, gestational age, sex
HC:AC
- symmetrically small - likely constitutional
- asymmetric - placental insufficiency
Brain-sparing effect identified on abnormal Doppler studies
Placental insufficiency can result in impaired foetal kidney function which will result in reduced amniotic fluid volume

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What are the investigations for SGA babies?

USS
Detailed foetal anatomical survey
Uterine artery Doppler 
Karyotyping
Screening for infections (congenital cytomegalovirus, toxoplasmosis, syphilis, malaria)

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How is SGA prevented?

Manage modifiable risk factors (smoking cessation, optimising maternal disease)
Women at high risk of pre-eclampsia - aspirin at 16 weeks to delivery

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What surveillance is done for SGA babies?

UAD - primary surveillance tool
- repeat every 14 days (more frequently if abnormal/consider delivery)
Symphysis fundal height
MCA Doppler
Ductus venosus Doppler
CTG
Amniotic fluid volume

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What is the management of an SGA baby at delivery between 24 and 35+6 week?

Give a single course of antenatal steroids

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What is the indication for delivery and the mode at <37 weeks gestation for an SGA baby?

Indication: absent/reverse end-diastolic flow on doppler
Mode: c section

What is the indication for delivery and the mode of delivery by 37 weeks?

Abnormal UAD/MCA doppler

Mode - offer induction

What is the indication for delivery and the mode of delivery at 37 weeks?

Normal UAD

Can offer induction

What are the neonatal complications of SGA?

Birth asphyxia
Meconium aspiration
Hypothermia
Hypo/hyperglycaemia
Polycythaemia
Retinopathy of prematurity
Persistent pulmonary hypertension
Pulmonary haemorrhage
Necrotising enterocolitis

What are the long term complications of SGA?

Cerebral palsy
T2DM
Obesity
Hypertension
Precocious puberty
Behavioural problems
Depression
Alzheimer’s disease
Cancer (breast, ovarian, colon, lung, blood)

What is red blood cells isoimmunisation?

It describes the production of antibodies in response to an isoantigen present on an erythrocyte.

What is maternal isoimmunisation and what is its significance?

Occurs when the mother’s immune system is sensitised to antigens on foetal erythtocytes during a sensitising event (antepartum haemorrhage/abdo trauma/delivery) resulting in the production of IgG antibodies.
In subsequent pregnancies, these antibodies can cross the placenta and attack attack the foetal red blood cells
This leads to haemolysis and anaemia (haemolytic disease of the newborn)

Describe the process of rhesus D isoimmunisation.

A RhD- woman has a foetus that is RhD+ and produces antibodies during delivery.
Later becomes pregnant with another RhD+ baby.
Antibodies cross the placental, enter foetal circulation and bind to the RhD antigens on the erythrocyte surface membranes
Causes the foetal immune system to attack and destroy its own RBCs leading to fatal anaemia

What can be done to prevent maternal isoimmunisation? How does this work?

Administer anti-D immunoglobulin

It binds to RhD+ cells in the maternal circulation and therefore no immune response is stimulated

What are the indications for giving anti-D immunoglobulin?

Rhesus D women following a sensitising event: - invasive obstetric testing (amniocentesis/chronic villus sampling) - antepartum haemorrhage - ectopic pregnancy - external cephalic version - fall/abdominal trauma - intrauterine death - miscarriage - TOP - delivery

What are the blood tests that should be considered following a sensitising event?

Maternal blood group and antibody screen - determines ABO and RhD blood groups - detects antibodies directed against RBC surface antigens (except A and B) Feto-maternal haemorrhage test/Kleihauer test - assesses how much foetal blood has entered the maternal circulation If sensitising event after 20 weeks gestation - determines how much anti-D Ig should be administered

What tests should be done after delivery in terms of RhD?

Rhesus status of baby (if positive and mother negative and FMH test should be performed and at least 500 IU of anti-D Ig administers) The dose can then be increased depending on the size of the FMH

What is the management of sensitisation events at less than 12 weeks gestation? What are the indications?

Indications - ectopic pregnancy, molar pregnancy, termination, heavy uterine bleeding Investigations: Maternal blood group and antibody screen (to confirm RhD-, and that no anti-D antibodies are already formed). Dose: 250 IU anti-D, within 72 hours of the event. 12-20 weeks’ gestation

What is the management of sensitisation events at less than 12-20 weeks gestation? What are the indications?

Indications: All potential sensitising events Investigations: Maternal blood group and antibody screen (to confirm RhD-, and that no anti-D antibodies are already formed). Dose: 250 IU anti-D, within 72 hours of the event.

What is the management of sensitisation events at over 20 weeks gestation? What are the indications?

Indications: All potential sensitising events Investigations: Maternal blood group and antibody screen (to confirm RhD-, and that no anti-D antibodies are already formed). Feto-maternal haemorrhage test. Dose: 500 IU within 72 hours of the event (dose can be increased depending on the size of the FMH).

What is the red blood cell isoimmunisation screening and prophylaxis in the UK?

All pregnant women have a maternal blood group (ABO and RhD typing), and an antibody screen performed at the booking visit (8-12 weeks gestation). This is repeated at 28 weeks. If RhD-: offered routine antenatal anti-D prophylaxis (500 IU) at 28 and 34 weeks gestation. Some centres give a single (larger) dose at 34 weeks.

What is a prolonged pregnancy?

AKA post-term/post-dates Persisting for 42+ weeks 5-10% of pregnancies

What are the risk factors for prolonged pregnancy?

``` Nulliparity Maternal age over 40 Previous prolonged pregnancy High BMI FH of prolonged pregnancies ```

What are the complications of prolonged pregnancy?

Stillbirth Placental insufficiency - foetal acidaemia, meconium aspiration in labour, instrumental/Caesarian delivery Neonatal hypoglycaemia due to placental degradation (placental glycogen stores pelleted dueto lack of oxygen and nutrient transfer)

What are the clinical features of prolonged pregnancy?

None Static growth/macrosomia Oligohydraminos Presence of meconium (signs of staining e.g. on nails) Dry/flaky skin with reduced vernix (a wax, white substance coating the skin of newborn babies)

What are the differentials for prolonged pregnancy?

Inaccurate dating

What are the investigations done for prolonged pregnancy?

Dating between 11 and 13+6 weeks - most reliable as the foetus rarely shows signs of being constitutionally large or small until later in gestation USS to check growth, liquor volume Doppler

What is the management for prolonged pregnancies?

``` Membrane sweeps (from 40 weeks in nulliparous and 41 in parrous) Induction of labour (between 41 and 42 weeks) ```

How are women with prolonged pregnancy who decline induction of labour managed?

Twice weekly CTG monitoring and USS with amniotic fluid measurement in an attempt to identify foetal distress/other serious complication to mother or child If this does occur may need an emergency C section