Screening for fetal growth restriction with universal third trimester ultrasonography in nulliparous women in the Pregnancy Outcome Prediction (POP) study: a prospective cohort study

Abstract

SummaryBackgroundFetal growth restriction is a major determinant of adverse perinatal outcome. Screening procedures for fetal growth restriction need to identify small babies and then differentiate between those that are healthy and those that are pathologically small. We sought to determine the diagnostic effectiveness of universal ultrasonic fetal biometry in the third trimester as a screening test for small-for-gestational-age (SGA) infants, and whether the risk of morbidity associated with being small differed in the presence or absence of ultrasonic markers of fetal growth restriction.MethodsThe Pregnancy Outcome Prediction (POP) study was a prospective cohort study of nulliparous women with a viable singleton pregnancy at the time of the dating ultrasound scan. Women participating had clinically indicated ultrasonography in the third trimester as per routine clinical care and these results were reported as usual (selective ultrasonography). Additionally, all participants had research ultrasonography, including fetal biometry at 28 and 36 weeks' gestational age. These results were not made available to participants or treating clinicians (universal ultrasonography). We regarded SGA as a birthweight of less than the 10th percentile for gestational age and screen positive for SGA an ultrasonographic estimated fetal weight of less than the 10th percentile for gestational age. Markers of fetal growth restriction included biometric ratios, utero-placental Doppler, and fetal growth velocity. We assessed outcomes for consenting participants who attended research scans and had a livebirth at the Rosie Hospital (Cambridge, UK) after the 28 weeks' research scan.FindingsBetween Jan 14, 2008, and July 31, 2012, 4512 women provided written informed consent of whom 3977 (88%) were eligible for analysis. Sensitivity for detection of SGA infants was 20% (95% CI 15–24; 69 of 352 fetuses) for selective ultrasonography and 57% (51–62; 199 of 352 fetuses) for universal ultrasonography (relative sensitivity 2·9, 95% CI 2·4–3·5, p<0·0001). Of the 3977 fetuses, 562 (14·1%) were identified by universal ultrasonography with an estimated fetal weight of less than the 10th percentile and were at an increased risk of neonatal morbidity (relative risk [RR] 1·60, 95% CI 1·22–2·09, p=0·0012). However, estimated fetal weight of less than the 10th percentile was only associated with the risk of neonatal morbidity (pinteraction=0·005) if the fetal abdominal circumference growth velocity was in the lowest decile (RR 3·9, 95% CI 1·9–8·1, p=0·0001). 172 (4%) of 3977 pregnancies had both an estimated fetal weight of less than the 10th percentile and abdominal circumference growth velocity in the lowest decile, and had a relative risk of delivering an SGA infant with neonatal morbidity of 17·6 (9·2–34·0, p<0·0001).InterpretationScreening of nulliparous women with universal third trimester fetal biometry roughly tripled detection of SGA infants. Combined analysis of fetal biometry and fetal growth velocity identified a subset of SGA fetuses that w...

Accelerated Fetal Growth Prior to Diagnosis of Gestational Diabetes Mellitus: A Prospective Cohort Study of Nulliparous Women

“…The Pregnancy Outcome Prediction study was conducted at the Rosie Hospital, Cambridge, U.K., and has previously been described in detail (9,10). In brief, it was a prospective cohort study of nulliparous women with a viable singleton pregnancy who attended the hospital for their dating ultrasound scan between 14 August 2008 and 31 July 2012.…”

“…The conduct and descriptive data of the research ultrasounds have previously been described in detail (9,10). In brief, gestational dating was performed using ultrasound, and 99.5% of these examinations were performed prior to 15 wkGA.…”

Role of uteroplacental and fetal Doppler in identifying fetal growth restriction at term

“…De Jong showed in 1999 that the fetal growth rate was significantly lower in pregnancies that had operative delivery for presumed fetal distress (20.9 g/day) or neonatal unit admission (20.3 g/day) compared to those with uncomplicated outcome (21.9 g/day) [29]. A large screening study of 4,512 nulliparous woman recruited over a four year period in Cambridge UK [30] found that an EFW below the 10 th centile was associated with an increased risk of neonatal morbidity, but only if the fetal AC growth velocity was in the lowest decile (relative risk of 17.6). In 2008, Eixarch showed that only fetuses with signs of cerebral redistribution, identified as those with a low middle cerebral artery (MCA) pulsatility index (PI), suffered from lower communication and problem solving scores in childhood [31].…”

“…It is notable that the improvement of the detection of SGA neonates using assessment of the fetal growth (biometry) was associated with a high false positive rate (two false positives for each additional SGA neonate detected), as shown in the Cambridge screening study [30]. It is clear, therefore, that additional parameters such as fetal Doppler or biochemical markers, such as placental growth factor, are required to optimize the identification of fetuses at risk of adverse outcome [30,32].…”

“…It is clear, therefore, that additional parameters such as fetal Doppler or biochemical markers, such as placental growth factor, are required to optimize the identification of fetuses at risk of adverse outcome [30,32].…”