Presentation on theme: "Fetal Growth Patterns: how to improve the antenatal detection of the Small or Large for gestational age fetus in a low risk population Dr Alison Munt Obstetrician."— Presentation transcript:
1Fetal Growth Patterns: how to improve the antenatal detection of the Small or Large for gestational age fetus in a low risk populationDr Alison MuntObstetrician and GynaecologistLyell McEwin Hospital, Elizabeth Vale.Adelaide Obstetrics, Goodwood.IntroductionAsk questions at any stage and ill endeavour to answer them
2Fetal Growth Patterns What is considered Abnormal fetal growth Small for gestational age (SGA)/intrauterine growth restriction (IUGR)Large for gestational age (LGA)/macrosomiaIncreased morbidity and mortalityAntenatal Assessment of risk factorsDetection/screeningAbdominal palpation/SFH measurementsCustomised SFH chartIndications for referralHow to manage a patient SGA/LGA fetus
3Normal Fetal GrowthDefined as the expression of the genetic potential to grow in a way that is neither constrained nor promoted by internal or external factors (SA perinatal Practice Guidelines)Normal singleton fetal growth (Resnik 2002)5g/day at 14-15weeks10g/day at 20w30-35g/day at weeksRule of thumb in third trimester is 200g a week expected growth.
4Small for Gestational Age (SGA) Birthweight below the 10th centile of weight for gestation. This does not necessarily indicate fetal growth restriction (SA Perinatal Practice Guidelines)
5Intrauterine Growth Restriction (IUGR) a condition in which a fetus is unable to achieve its genetically determined potential size.This functional definition seeks to identify a population of fetuses at risk for modifiable but otherwise poor outcomes.
6Not all SGA fetuses are IUGR (visa versa) 40% constitionally smallOnly 40% of SGA babies benefit from interventionNot all fetuses that are SGA are pathologically growth restricted and, in fact, may be constitutionally small. Similarly, not all fetuses that have not met their genetic growth potential are in less than the 10th percentile for estimated fetal weight (EFW).Intrinsically small chromosomal or environmental etiology- not benefit from interventionOnly 40% of SGA babies benefit from intervention
7Large for Gestational Age/Macrosomia Interchangeable termsfetal growth beyond a specific weight, usually 4,000 g or 4,500 g regardless of the fetal gestational age.Results from large cohort studies support the use of 4,500 g as the weight at which a fetus should be considered macrosomic.Weighing the newborn after delivery is the only way to accurately diagnose macrosomia.
8Fetal Growth Patterns INCREASED MORBIDITY AND MORTALITY Why screen for SGA and LGA babies: Small (and large) for gestational age babies are at an increased risk of associated morbidity and mortality.
9Morbidity associated with IUGR Meconium stained liquorAbnormal heart rate patterns intrapartumIntrauterine fetal deathHypoxic ischaemic encephalopathyPoor neurological developmentDelay in cognitive developmentSudden infant death syndrome
10Morbidity associated with IUGR In adult lifeType 2 diabetes andhypertension (RCOG 2002)mental health problemsChildren born below 2nd percentile at increased risk: (Zubrick etal)mental health morbidity (OR 2.9; 95% CU, )Academic impairment (OR, 6; 95% CI, )Poorer general health (OR, 5.1; 95% CI, )Increasingly, data support the idea that long-term consequences of IUGR last well into adulthood. Several authors have noted that these individuals have a greater predisposition to develop a metabolic syndrome later in life, manifesting as obesity, hypertension, hypercholesterolemia, cardiovascular disease, and type 2 diabetes. Several hypotheses have been proposed to explain this relationship. Hales and Barker proposed the so-called thrifty phenotype in This idea suggests that intrauterine malnutrition results in insulin resistance, loss of pancreatic beta-cell mass, and an adult predisposition to type 2 diabetesIn a study performed in Western Australia, Zubrick et al showed that children born below the second percentile for weight were at significant risk for mental health morbidity (odds ratio, 2.9; 95% CI, ), academic impairment (odds ratio, 6; 95% Cl, ), and poorer general health (odds ratio, 5.1; 95% Cl, ). Specifically, Tideman et al have shown that impaired fetal circulation, as demonstrated by Doppler studies, in association with IUGR, results in worsened cognitive function in adulthood. Tideman E etal 2007
11Morbidity associated with LGA Maternal risks:Protracted or arrested labourOperative vaginal deliveryCaesarean deliveryGenital tract lacerationsPostpartum haemorrhageUterine ruptureFetal and neonatal risks:Shoulder dystocia leading to birth trauma (brachial plexus injury, fracture) or asphyxiaNeonatal hypoglycemiaRiskACOG emphasizes that an increased risk of cesarean delivery is the primary maternal risk factor associated with macrosomia. Results from cohort studies demonstrate that the risk of cesarean delivery in women attempting a vaginal delivery at least doubles when the fetal weight is estimated to be more than 4,500 g.Although rare (complicating 1.4 percent of all vaginal deliveries), shoulder dystocia is the most serious complication associated with fetal macrosomia. When birth weight is more than 4,500 g, however, the risk is increased to 9.2 to 24 percent in pregnant women without diabetes and to 19.9 to 50 percent in pregnancies complicated by diabetes. However, while macrosomia increases risk, shoulder dystocia also occurs unpredictably in infants of normal birth weight.Fracture of the clavicle and damage to the nerves of the brachial plexus are the most common fetal injuries associated with macrosomia. In macrosomic infants, the risk of clavicular fracture and brachial plexus injury is approximately 10-fold and 18- to 21-fold, respectively, when birth weight is more than 4,500 g.s of macrosomia
12Morbidity associated with LGA Long-term risks in offspring:Development of impaired glucose tolerance and obesityDevelopment of metabolic syndromeIncrease in aorta intima-media thickness, left ventricular mass, and abnormal lipid profile
13Detection: Antenatal care Is fetus growing at a normal rate = according to its genetic potential?Abdominal palpationMeasurement of SFHBUT FIRST:Identify those patients not suitable for low risk care or routine screeningWho are the patients that require additional screening ie. Serial USS
14Identiftying High Risk Patients At risk of IUGRMultiple pregnancyPrevious hx of IUGRPrevious hx of Unexplained stillbirthHypertension/past hx of PETAntiphospholipid syndromeAutoimmune diseaseRenal conditionsDiabetesMaternal age 40+Alcohol, drug misuse
15Identiftying High Risk Patients At risk of macrosomiaHigh body mass indexMultiparityAdvanced maternal ageMaternal diabetesPost term pregnancyMale infantPrevious macrosomic infantExcessive weight gain in pregnancyMaternal birth weight over 4000 grams
16Indications for serial growth USS monitoring Increased risk based on an antenatal assessmentRisk factors mentionedPAPPA low (<0.4)Single umbilical artery on morphologyFundal Height measuring not possible/unreliablePolyhydramniosHigh BMI (35+)Large fibroids
17Detection: Antenatal care Is fetus growing at a normal rate = according to its genetic potential?Abdominal palpationMeasurement of SFHAntenatal detection of both the large fetus and the small fetus can possible reduce the morbidty and mortlaity that is associated with abnormal growth patterns.
18Abdominal Palpation: Leopold’s Maneurvers Factors that contributeto the limited predictiveValue of SFH measurement:Maternal obesityLarge fibroidshydramniosFetal lieHead engagementa: fundal gripb: umbilical gripc: pawlick’s gripd: pelvic gripMaternal obesity, abnormal fetal lie, large fiborids, hydramnios and fetal head engagtement contribute to the limited predictive accuracy of SFH measurement. Important to assess for these things.
19Abdominal PalpationLimited accuracy in the detection of a SGA neonate in low risk populationsLow risk populations (Bais etal 2004)sensitivity 19-21%, specificity 98%In mixed risk populations,the sensitivity increases to 32-44% (Hall etal 1980; Rosenberg etal 1982)In high risk populations53% for severe SGA (Bias etal 2004)
21Current SA guideline:The woman should be lying in the supine position with her head supported on a single pillow. The couch should be flatMeasure from the highest point of the fundus to the top of the symphysis pubis.Begin measuring from the fundus since this is the more variable end point.Measure with the tape scale facing downwars so that you are less influenced by previous results.Measurements should be recorded to the nearest 0.5 centimetre.WHO DOES ACTUALLY FOLLOW THE SA GUIDELINE??
22Single FH measurement approach “The fetus is most likely AGA if FH = Dates +/-2 cm”Probably not a satisfactory approach to screening for abn growth paternsA recent systematic review of five studies highlighted the wide variation of predictive accuracy of FSD measurement for a SGA infant. (NCCWCH 2008)Although early studies reported sensitivies of 56-86% and specifiecites of 80-93% for SFH detection of a SGA neonate, a large study of 2941 women reported SFH to be less predictive with a sensitivity of 27% and specificity of 88% (LR+ 2.22, 95% CI ; LR- 0.83, 95% CI ).Maternal obesity, abnormal fetal lie, large fiborids, hydramnios and fetal head engagtement contribute to the limited predictive accuracy of SFH measurement. SFH is associated with signifcant intra- and inter-observere variation and serial measurement may improve predictiv e accuracy.Antenatal detection rates of SGA fetus (25-30%)
23Case Primigravida presents at 36+ weeks Uneventful pregnancy Obstetric examination:Fetus: longitudinal lie, cephalic presentationFHR: 145 bpmFundal Height: 35.5 cmWhat is your estimate of the fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?Past practise has been to accept a SFH measurement that is within 2cm of the gestational age. Should be reassured by that finding.
24SFH measurementSFH is associated with significant intra- and inter-observation variationContinuity of care provider further improves the accuracy of fetal growth surveillanceserial measurement may improve predictive accuracy.Even better: Customised SFH charts!
25FH Chart SA hand held record Who does actually plot FH in chart?
26Our case 36 weeks: serial plot population based chart What is your view about fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?
27Customised SFH ChartsEvidence that improves detection whilst reducing unnecessary referrals for investigations (Gardosi and Francis 1999; Roex 2012)Customised antenatal growth charts are now recommended by the RCOG (RCOG guidelines 2002)Also currently being used in SA hospitals:Lyell McEwin Hospital ServiceFlinders Medical CentreJason Gardosi, West Midlands Perinatal Institute,Birmingham B6 5RQ, UKEvidence that plotting serial fundal height measurements on individually customised growth charts can significantly improve detection of babies that are growing inappropriately, whilst reducing unnecessary referrals for investigations (Gardosi and Francis 1999; Roex 2012)Customised antenatal growth charts are now recommended by the RCOG (RCOG guidelines 2002)Also currently being used in SA hospitals includingLMHSFMC
29Example Customised FH Chart FUNDAL HEIGHTCMULTRASOUNDEST. FETAL WEIGHTThe following data is used to generate these customised chartsEthnic originMaternal heightweightParityGestation, sex, andweight of previousbabies in gramsplaced in the maternal notes until the morphology scan appointmentFollowing the morph scan a copy of the customised growth chart will be included in the maternal hand held record to replace the generic chartPathological factors known to affect birth weight and growth such as smoking hypertension, diabetes and preterm delivery are excludedGESTATION WKS
31Case Primigravida presents at 36+ weeks Uneventful pregnancy Obstetric examination:Fetus: longitudinal lie, cephalic presentationFHR: 145 bpmFundal Height: 35.5 cmWhat is your estimate of the fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?
32Our case 36 weeks: serial plot population based chart What is your view about fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?
33Our case: serial FH plot customised chart What is your view about fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?
35What about the ‘evidence’? No randomised controlled trials (Level II)One cohort trial comparing laying on hands with plotting on customised chart (level III)One cohort trial comparing non plotting with plotting on customised chart (level III)No trials comparing customised with non-customised SFH chartsObservational studies suggest that customised SFH charts may improve the detection of a SGA neonate.
36Serial plotting FH in customised chart 1. West Midlands UK 1999Improved detection of SGA fetus 29.2% vs 47.9% (OR 2.2; 95% CI ; p 0.03)Gardosi J and Francis A. BJOG 1999;106(4):309-12Use of customised charts was also associated with fewer referrals for investigation and fewer admission.2. Adelaide NALHN 2012Improved detection rate 24.8% vs 50.6% (OR 3.1; CI ; P<0.001 )Roex et al Aust N Z J Obstet Gynaecol 2012; 52:78-82.No trials were indentified that compared customised with non-customised SFH charts and thus evidence for their effectivemeness on outcomes such as perinatal morbidity/mortality is lacking.However observational studies suggest that customised SFH charts may improve the detetion of a SGA neonate.In one study, use of customised charts, with referral when a single SFH measurement fell below the 10th centile or the last two measurements were above the 10th centile but the slpe was flatter than the 10th centlie line, resulted in improved sensitivity for a SGA neonate (48% versue 29% OR 2.2, 95% CI ) compared to abdominal palpation. ( Gardosi 1999)Use of customised charts was also associated wth fewer referrals for investigation and fewer admission. An audit from the West Midlands also showed that the use of customised SFH charts detected 36% of SGA neonates compared with only 16% when customised charts were not used. (Wright etal 2006)
37When to refer for Growth USS: ‘Fetal GROW’ guideline NALHN 1. Low first fundalheight
38When to refer for Growth USS: ‘Fetal GROW’ guideline NALHN 2. Static growth
39When to refer for Growth USS: ‘Fetal GROW’ guideline NALHN 3. Slow growth
40When to refer for Growth USS: ‘Fetal GROW’ guideline NALHN 4. Accelerated Growth
41‘Fetal GROW’ guideline NALHN ANC visit > 24 wksPLOT FH in Gardosi ChartLow first FHStatic growthSlow growthAccelerated growthUS Fetal growthAssess US & Plot EFW in Gardosi ChartEFW>P10 & US findings US EFW <P10Back to routine care and FH plottingURGENT REFERRALOBSTETRICAL REVIEW
42Where to find Customised charts growth charts just download Australian FH charts
43Improved detection: so what? ? Decreased mortality and morbidityStillbirths are the largest contributor to perinatal mortality. They are a central indicator of patient safetyand quality of care, and an essential component of the NHS Outcomes Framework . West Midlands stillbirth rates have been consistently well above national rates for the last 50 years. Recent regional initiatives by the Perinatal Institute, in collaboration with SHA, PCTs and provider Trusts,have led to significantly fewer stillbirths; this has resulted in West Midland rates falling, for the first timeever, to below the national average. This reduction is due to fewer deaths associated with fetal growth restriction and follows a comprehensiveprogramme of audit, training, and implementation of protocols to increase antenatal detection ofpregnancies at risk. The decrease is most marked in areas which have been at the forefront of implementation, and has led toreductions which, if extrapolated across the region, would lead to 78 fewer stillbirth each year. It is essential that this momentum is maintained and built upon, and that stillbirth prevention remains acontinued priority in the West Midlands.
44Crude Stillbirht Rates 2000-2009 West Midlands 5 Crude Stillbirht Rates West Midlands 5.74, England and Wales 5.33 Figure 1 shows crude stillbirth rates since2000 (3 year moving average) for West Midlandsand England & Wales. Stillbirth rates have beenconsistently above the national average since theearliest available (1963) regional ONS data.The 10 year average (2000‐2009) West Midlandsrate: 5.74 (CI 5.56‐5.92) is significantly above thatfor England & Wales: 5.33 (CI 5.28‐5.39) (Fig 2).
45Crude stillbirth rates 2000-2011 West Midlands versus England/Wales Significant drop in West Midlands, Gardosi’s health region 5.02 vs 5.24 / 1000 (p<0.05)Drop most significantin areas werecustomised FHcharts wereintroduced firstPerinatal Institute Birmingham 2011 Figure 2: There has been a significant (p<0.05)downward trend in West Midlands stillbirth rates,while national rates have remained relatively staticThis reduction has resulted, for the first time, inthe regional stillbirth rate falling below thenational average in 2011: 5.01 vs 5.24 /1000.Compared to the expected number based on the10 year baseline, this drop represents 53 fewerstillbirths in the West Midlands in 2011.attributed to increasedefforts in prevention, including the CommunityGrowth Scanning project (CoGS)  commencedin 2010, which has led to significantly improveddetection of FGR in at‐risk pregnancies .
46ConclusionIn a low risk population serial plotting of the Fundal Height on a customised Gardosi chart combined with ‘GROW guideline’ appears to be the preferred methodLaying hands on or just measuring FH and non plotting = non evidence based practice
47Surveillance for suspected IUGR 2 weekly growth USSWeekly USS for AFI and dopplerWeekly CTGDelivery </= 37 weeksMode: often don’t tolerate labour
48Management of Macrosomia + poorly controlled diabetes may lead to early IOLEvidence supports:Offering elective LSCS if GDM and EFW >4.5kg or no GDM and EFW >5kg.No evidence for improved outcomes with IOL (Two systematic reviews concluded that labour induction for suspected fetal macrosomia did not result in a lower rate of shoulder dystocia or caesarean delivery than expectant management)