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- Matthews Mathai
- Training in Reproductive Health Research
Geneva 2006
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- Terms and definitions
- Factors influencing size at birth
- Problems associated with impaired fetal growth and their significanc=
e
- Diagnosis
- Management
- Prevention
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- Prematurity
- Low birthweight (LBW)
- Small for gestational age (SGA)
- Intrauterine growth restriction (IUGR)
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- Should refer to functional immaturity of organ systems
- E.g. Respiratory immaturity
- When is functional maturity achieved?
- Preterm refers to relation to chronological age
- Refers to gestation less than 37 weeks
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- All infants weighing less than 2500 g at birth
- Does not consider gestational age
- Different problems included in the same group
- Small and average sized preterm infants
- Small sized term infant
- Proxy indicator for growth restriction and prematurity
- VLBW < 1500g; ELBW < 1000 g
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- Smaller than expected for given gestational age
- How much smaller?
- Less than 10th centile
- Less than 5th centile
- Less than 2 SD
- Synonyms
- Small for dates (SFD), Light for dates (LFD)
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- Restriction or slowing of the rate of intrauterine fetal growth
- Not synonymous with SGA
- Demonstration of slowing of growth rate
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- Size at birth depends on
- Gestation at birth
- Fetal growth rate
- A baby may be small at birth because
- It was born earlier than normal, or
- Its rate of intrauterine growth was slower than normal, or
- It had impaired growth and was born early
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- Fetal
- Placental
- Maternal
- Environmental
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- Abnormal karyotype
- Fetal sex
- Male fetuses heavier by 100-150 g
- Genetic influences
- Parental size
- Ethnic group
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- Placental infections
- Placental infarction
- Placentation
- Later born babies are 100-150 g heavier than first born babies
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- Maternal size
- limiting effects
- adjusting birthweight centiles for maternal height
- Maternal illness
- Nutrition
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- Altitude
- Lower birthweight at higher altitudes
- Tobacco abuse
- Active smoking
- Passive smoking
- Tobacco chewing
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- Cooking fuels
- Coal, wood, animal dung
- Poor ventilation
- Carbon monoxide inhalation
- Other heavy manual work
- Agriculture
- Carrying water
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- Low birthweight babies are approximately 20 times more likely to die
than heavier babies
- Goal of reducing low birthweight incidence by at least one-third bet=
ween
2000 and 2010 is a major goal in A World Fit for Children (UN 2002=
)
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- Immediate
- Increased risk of suspected fetal distress
- Increased risk of interventions
- Increased risk of problems after birth
- Hypoglycemia, hypothermia, poor feeding
- Medium to long term
- Learning disabilities
- Increased risk of hypertension, heart disease, diabetes
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- Birthweight < 5th centile OR 5.6
- Birthweight 5th - 10th centile OR 2.8
- Birthweight 10th 15th centile OR 1.9
- Growth rate in third trimester is a better predictor of intrapartum
problems and immediate perinatal outcomes than estimates of fetal si=
ze
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- Identification of risk factors
- Maternal weight gain
- Abdominal palpation
- Tape measurements
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- Biochemical methods
- Ultrasound
- Routine vs selective use
- Fetal biometry
- Biophysical score
- Cardiotocography
- Doppler
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- Cross sectional data on birthweight and gestation
- Graph of birthweight against gestation
- Cut off levels for classification
- 10th and 90th centile
- Small, appropriate and large for gestation
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- Hospital births
- Physiological and pathological factors influencing size at birth
- Misclassification if appropriate adjustments are not made
- Ethnic composition
- Accuracy of gestation
- Growth and preterm births
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- Possible everywhere but requires training and experience
- Abdominal palpation
- Tape measurements of fundal height
- Widely used for assessing fetal growth and size
- Insufficient evidence from only randomized trial
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- Hospital based
- Mostly cross-sectional studies
- Measurements include
- Head size (BPD, HC)
- Abdominal circumference
- Femur length
- Weight estimation
- Interval growth measurements
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- Equations for estimation of fetal weight
- Hadlock equations commonly used
- Rossavik model
- Early estimate of fetal growth rate
- Project fetal weight at birth based on growth rate
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- Physiological factors
- Size of the mother
- Birth order
- Sex
- Ethnicity
- Adjustments made while interpreting size at birth
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- For physiological factors
- Computer generated graph (Gardosi et al)
- Higher antenatal detection of small for dates (48% vs 24%; OR 2.2, 9=
5%
CI 1.3-1.5)
- OR for stillbirth in small for dates by
- Individualised graph 6.1 (95% CI 5.0-7.5)
- Standard graph 1.2 (95% 0.8-1.9)
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- NO EVIDENCE OF BENEFIT
- Bed rest in hospital
- Hormone therapy
- Betamimetic therapy
- Antihypertensive therapy
- Nutrient supplementation
- Maternal oxygen administration
- Plasma volume expansion
- Routine ultrasound
- Cardiotocography
- Biophysical scoring
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- Delivery at the appropriate time
- Will the baby survive better in the uterus or outside it ?
- Nursery facilities
- Costs of treatment
- Reducing birth asphyxia
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- Doppler ultrasound for deciding on the time of delivery
- Fewer inductions OR 0.83 (0.74-0.93)
- Less hospital admissions OR 0.56 (0.43-0.72)
- Corticosteroids prior to preterm delivery
- Less RDS OR 0.53 (0.44-0.63)
- Less IVH OR 0.48 (0.48-0.75)
- Fewer neonatal deaths OR 0.60 (0.48-0.75)
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- Amnioinfusion in labour
- Less FHR decelerations RR 0.54 (0.43-0.68)
- Less CS for suspected fetal distress RR 0.35 (0.24-0.52)
- Nursery stay > 3 days RR 0.40 (0.26-0.62)
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- Smoking cessation
- LBW RR 0.81 (0.70-0.94)
- Preterm births RR 0.84 (0.72-0.98)
- Mean birthweight increase 33 g (11-55g)
- Balanced energy and protein supplementation
- Less SGA RR 0.68 (0.56-0.84)
- Treatment of asymptomatic bacteriuria
- LBW/Preterm RR 0.60 (0.45-0.80)
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- Impaired fetal growth is associated with increased perinatal morbidi=
ty
and mortality and increased risks in later life
- Diagnosis is made by demonstrating slowing of growth over a period of
time using appropriate standards for fetal size
- There are few beneficial interventions that improve fetal growth
- Delivery at the appropriate time with skilled newborn care is the key to impro=
ved
newborn survival
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