Obstetrics and Gynaecology - Research Publications
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ItemDeclining invasive prenatal diagnostic procedures: A comparison of tertiary hospital and national data from 2012 to 2015(WILEY, 2017-04)BACKGROUND: In recent years, the superior accuracy of maternal plasma cell-free DNA-based prenatal screening has resulted in >50% national decline in amniocenteses and chorionic villus sampling (CVS), creating new implications for specialist training. OBJECTIVE: To compare the annual figures on amniocenteses and CVS in a tertiary hospital with national population-based trends between 2012 and 2015. METHODS: Retrospective study examining the amniocentesis and CVS procedures performed in a tertiary hospital between 2012 and 2015. Numbers of procedures, indications for testing, type of test and diagnostic results were analysed. Trends in the annual numbers of procedures were compared to national population-based data from Medicare Benefits Schedule database. RESULTS: The annual numbers of diagnostic procedures in our tertiary centre fell from 267 to 215 over the study period, representing a 19.5% decline. This was significantly smaller than the corresponding national decline of 53.7% for the same period (P < 0.0001). In 2015, ultrasound abnormality (including nuchal translucency ≥ 3.5 mm) surpassed high-risk screening results as the most common indication for invasive testing. Thirty percent of procedures performed for an ultrasound abnormality occurred prior to 18 weeks gestation. CONCLUSION: Our tertiary centre experienced a relatively smaller decline in prenatal diagnostic procedures compared with national figures, largely due to an increase in testing for ultrasound abnormalities. Our results demonstrate the increasing contribution of first trimester ultrasound in the detection of fetal abnormalities in the cell-free DNA era and the continued viability of specialist training in invasive procedures.
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ItemReduced growth velocity across the third trimester is associated with placental insufficiency in fetuses born at a normal birthweight: a prospective cohort study(BMC, 2017-08-31)BACKGROUND: While being small-for-gestational-age due to placental insufficiency is a major risk factor for stillbirth, 50% of stillbirths occur in appropriate-for-gestational-age (AGA, > 10th centile) fetuses. AGA fetuses are plausibly also at risk of stillbirth if placental insufficiency is present. Such fetuses may be expected to demonstrate declining growth trajectory across pregnancy, although they do not fall below the 10th centile before birth. We investigated whether reduced growth velocity in AGA fetuses is associated with antenatal, intrapartum and neonatal indicators of placental insufficiency. METHODS: We performed a prospective cohort study of 308 nulliparous women who subsequently gave birth to AGA infants. Ultrasound was utilised at 28 and 36 weeks' gestation to determine estimated fetal weight (EFW) and abdominal circumference (AC). We correlated relative EFW and AC growth velocities with three clinical indicators of placental insufficiency, namely (1) fetal cerebroplacental ratio (CPR; CPR < 5th centile reflects placental resistance, and blood flow redistribution to the brain - a fetal response to hypoxia); (2) neonatal acidosis after the hypoxic challenge of labour (umbilical artery (UA) pH < 7.15 at birth); and (3) low neonatal body fat percentage (BF%, measured by air displacement plethysmography) reflecting reduced nutritional reserve in utero. RESULTS: For each one centile reduction in EFW growth velocity between 28 and 36 weeks' gestation, there was a 2.4% increase in the odds of cerebral redistribution (CPR < 5th centile, odds ratio (OR) (95% confidence interval) = 1.024 (1.005-1.042), P = 0.012) and neonatal acidosis (UA pH < 7.15, OR = 1.024 (1.003-1.046), P = 0.023), and a 3.3% increase in the odds of low BF% (OR = 1.033 (1.001-1.067), P = 0.047). A decline in EFW of > 30 centiles between 28 and 36 weeks (compared to greater relative growth) was associated with cerebral redistribution (CPR < 5th centile relative risk (RR) = 2.80 (1.25-6.25), P = 0.026), and a decline of > 35 centiles was associated with neonatal acidosis (UA pH < 7.15 RR = 3.51 (1.40-8.77), P = 0.030). Similar associations were identified between low AC growth velocity and clinical indicators of placental insufficiency. CONCLUSIONS: Reduced growth velocity between 28 and 36 weeks' gestation among fetuses born AGA is associated with antenatal, intrapartum and neonatal indicators of placental insufficiency. These fetuses potentially represent an important unrecognised cohort at increased risk of stillbirth and may warrant more intensive antenatal surveillance.