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 and Gynaecologist Lyell McEwin Hospital, Elizabeth Vale. Adelaide Obstetrics, Goodwood. Introduction Ask questions at any stage and ill endeavour to answer them

Fetal Growth Patterns What is considered Abnormal fetal growth Small for gestational age (SGA)/intrauterine growth restriction (IUGR) Large for gestational age (LGA)/macrosomia Increased morbidity and mortality Antenatal Assessment of risk factors Detection/screening Abdominal palpation/SFH measurements Customised SFH chart Indications for referral How to manage a patient SGA/LGA fetus

Normal Fetal Growth Defined 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 14-15weeks 10g/day at 20w 30-35g/day at 32-34 weeks Rule of thumb in third trimester is 200g a week expected growth.

Small 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)

Intrauterine 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.

Not all SGA fetuses are IUGR (visa versa) 40% constitionally small Only 40% of SGA babies benefit from intervention Not 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 intervention Only 40% of SGA babies benefit from intervention

Large for Gestational Age/Macrosomia Interchangeable terms fetal 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.

Fetal 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.

Morbidity associated with IUGR Meconium stained liquor Abnormal heart rate patterns intrapartum Intrauterine fetal death Hypoxic ischaemic encephalopathy Poor neurological development Delay in cognitive development Sudden infant death syndrome

Morbidity associated with IUGR In adult life Type 2 diabetes and hypertension (RCOG 2002) mental health problems Children born below 2nd percentile at increased risk: (Zubrick etal) mental health morbidity (OR 2.9; 95% CU, 1.18-7.12) Academic impairment (OR, 6; 95% CI, 2.25-16.06) Poorer general health (OR, 5.1; 95% CI, 1.69-15.52) 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 1992. This idea suggests that intrauterine malnutrition results in insulin resistance, loss of pancreatic beta-cell mass, and an adult predisposition to type 2 diabetes In 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, 1.18-7.12), academic impairment (odds ratio, 6; 95% Cl, 2.25-16.06), and poorer general health (odds ratio, 5.1; 95% Cl, 1.69-15.52).[9] 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.[10] Tideman E etal 2007

Morbidity associated with LGA Maternal risks: Protracted or arrested labour Operative vaginal delivery Caesarean delivery Genital tract lacerations Postpartum haemorrhage Uterine rupture Fetal and neonatal risks: Shoulder dystocia leading to birth trauma (brachial plexus injury, fracture) or asphyxia Neonatal hypoglycemia RiskACOG 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

Morbidity associated with LGA Long-term risks in offspring: Development of impaired glucose tolerance and obesity Development of metabolic syndrome Increase in aorta intima-media thickness, left ventricular mass, and abnormal lipid profile

Detection: Antenatal care Is fetus growing at a normal rate = according to its genetic potential? Abdominal palpation Measurement of SFH BUT FIRST: Identify those patients not suitable for low risk care or routine screening Who are the patients that require additional screening ie. Serial USS

Identiftying High Risk Patients At risk of IUGR Multiple pregnancy Previous hx of IUGR Previous hx of Unexplained stillbirth Hypertension/past hx of PET Antiphospholipid syndrome Autoimmune disease Renal conditions Diabetes Maternal age 40+ Alcohol, drug misuse

Identiftying High Risk Patients At risk of macrosomia High body mass index Multiparity Advanced maternal age Maternal diabetes Post term pregnancy Male infant Previous macrosomic infant Excessive weight gain in pregnancy Maternal birth weight over 4000 grams

Indications for serial growth USS monitoring Increased risk based on an antenatal assessment Risk factors mentioned PAPPA low (<0.4) Single umbilical artery on morphology Fundal Height measuring not possible/unreliable Polyhydramnios High BMI (35+) Large fibroids

Detection: Antenatal care Is fetus growing at a normal rate = according to its genetic potential? Abdominal palpation Measurement of SFH Antenatal detection of both the large fetus and the small fetus can possible reduce the morbidty and mortlaity that is associated with abnormal growth patterns.

Abdominal Palpation: Leopold’s Maneurvers Factors that contribute to the limited predictive Value of SFH measurement: Maternal obesity Large fibroids hydramnios Fetal lie Head engagement a: fundal grip b: umbilical grip c: pawlick’s grip d: pelvic grip Maternal 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.

Abdominal Palpation Limited accuracy in the detection of a SGA neonate in low risk populations Low 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 populations 53% for severe SGA (Bias etal 2004)

Fundal Height Measurement

Current SA guideline: The woman should be lying in the supine position with her head supported on a single pillow. The couch should be flat Measure 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??

Single FH measurement approach “The fetus is most likely AGA if FH = Dates +/-2 cm” Probably not a satisfactory approach to screening for abn growth paterns A 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 1.77-2.78; LR- 0.83, 95% CI 0.77-0.90). 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%)

Case Primigravida presents at 36+ weeks Uneventful pregnancy Obstetric examination: Fetus: longitudinal lie, cephalic presentation FHR: 145 bpm Fundal Height: 35.5 cm What 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.

SFH measurement SFH is associated with significant intra- and inter-observation variation Continuity of care provider further improves the accuracy of fetal growth surveillance serial measurement may improve predictive accuracy. Even better: Customised SFH charts!

FH Chart SA hand held record Who does actually plot FH in chart?

Our case 36 weeks: serial plot population based chart What is your view about fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?

Customised SFH Charts Evidence 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 Service Flinders Medical Centre Jason Gardosi, West Midlands Perinatal Institute, Birmingham B6 5RQ, UK Evidence 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 including LMHS FMC

SA perinatal guidelines

Example Customised FH Chart FUNDAL HEIGHT CM ULTRASOUND EST. FETAL WEIGHT The following data is used to generate these customised charts Ethnic origin Maternal height weight Parity Gestation, sex, and weight of previous babies in grams placed in the maternal notes until the morphology scan appointment Following the morph scan a copy of the customised growth chart will be included in the maternal hand held record to replace the generic chart Pathological factors known to affect birth weight and growth such as smoking hypertension, diabetes and preterm delivery are excluded GESTATION WKS

Customised SFH charts Mrs Large Mrs Small

Case Primigravida presents at 36+ weeks Uneventful pregnancy Obstetric examination: Fetus: longitudinal lie, cephalic presentation FHR: 145 bpm Fundal Height: 35.5 cm What is your estimate of the fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?

Our case 36 weeks: serial plot population based chart What is your view about fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?

Our case: serial FH plot customised chart What is your view about fetal growth/weight? SGA<P10, AGA:P10-90 or LGA>P90?

Comparing trends

What 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 charts Observational studies suggest that customised SFH charts may improve the detection of a SGA neonate.

Serial plotting FH in customised chart 1. West Midlands UK 1999 Improved detection of SGA fetus 29.2% vs 47.9% (OR 2.2; 95% CI 1.1-4.5; p 0.03) Gardosi J and Francis A. BJOG 1999;106(4):309-12 Use of customised charts was also associated with fewer referrals for investigation and fewer admission. 2. Adelaide NALHN 2012 Improved detection rate 24.8% vs 50.6% (OR 3.1; CI 1.7-5.5; 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 1.1-4.5) 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)

When to refer for Growth USS: ‘Fetal GROW’ guideline NALHN 1. Low first fundal height

When to refer for Growth USS: ‘Fetal GROW’ guideline NALHN 2. Static growth

When to refer for Growth USS: ‘Fetal GROW’ guideline NALHN 3. Slow growth

When to refer for Growth USS: ‘Fetal GROW’ guideline NALHN 4. Accelerated Growth

‘Fetal GROW’ guideline NALHN ANC visit > 24 wks PLOT FH in Gardosi Chart Low first FH Static growth Slow growth Accelerated growth US Fetal growth Assess US & Plot EFW in Gardosi Chart EFW>P10 & US findings  US EFW <P10 Back to routine care and FH plotting URGENT REFERRAL OBSTETRICAL REVIEW

Where to find Customised charts www.gestation.net growth charts just download Australian FH charts

Improved detection: so what? ? Decreased mortality and morbidity Stillbirths are the largest contributor to perinatal mortality. They are a central indicator of patient safety and quality of care, and an essential component of the NHS Outcomes Framework [1].  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 time ever, to below the national average.  This reduction is due to fewer deaths associated with fetal growth restriction and follows a comprehensive programme of audit, training, and implementation of protocols to increase antenatal detection of pregnancies at risk.  The decrease is most marked in areas which have been at the forefront of implementation, and has led to reductions 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 a continued priority in the West Midlands.

Crude Stillbirht Rates 2000-2009 West Midlands 5 Crude Stillbirht Rates 2000-2009 West Midlands 5.74, England and Wales 5.33  Figure 1 shows crude stillbirth rates since 2000 (3 year moving average) for West Midlands and England & Wales. Stillbirth rates have been consistently above the national average since the earliest available (1963) regional ONS data. The 10 year average (2000‐2009) West Midlands rate: 5.74 (CI 5.56‐5.92) is significantly above that for England & Wales: 5.33 (CI 5.28‐5.39) (Fig 2).

Crude 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 significant in areas were customised FH charts were introduced first Perinatal 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 static This reduction has resulted, for the first time, in the regional stillbirth rate falling below the national average in 2011: 5.01 vs 5.24 /1000. Compared to the expected number based on the 10 year baseline, this drop represents 53 fewer stillbirths in the West Midlands in 2011. attributed to increased efforts in prevention, including the Community Growth Scanning project (CoGS) [4] commenced in 2010, which has led to significantly improved detection of FGR in at‐risk pregnancies [5].

Conclusion In a low risk population serial plotting of the Fundal Height on a customised Gardosi chart combined with ‘GROW guideline’ appears to be the preferred method Laying hands on or just measuring FH and non plotting = non evidence based practice

Surveillance for suspected IUGR 2 weekly growth USS Weekly USS for AFI and doppler Weekly CTG Delivery </= 37 weeks Mode: often don’t tolerate labour

Management of Macrosomia + poorly controlled diabetes may lead to early IOL Evidence 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)

Questions

‘Fetal GROW’ guideline NALHN ANC visit > 24 wks PLOT FH in Gardosi Chart Low first FH Static growth Slow growth Accelerated growth US Fetal growth Assess US & Plot EFW in Gardosi Chart EFW>P10 & US findings  US EFW <P10 Back to routine care and FH plotting URGENT REFERRAL OBSTETRICAL REVIEW