Screening For Fetal Growth Restriction Research Articles

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

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 were at increased risk of neonatal morbidity.FundingNational Institute for Health Research, Medical Research Council, Sands, and GE Healthcare.

151: Screening for fetal growth restriction (FGR) using universal third trimester ultrasonography: a prospective cohort study of 3,977 nulliparous women

151: Screening for fetal growth restriction (FGR) using universal third trimester ultrasonography: a prospective cohort study of 3,977 nulliparous women

Intrapartum perinatal mortality

Intrapartum perinatal mortality, the deaths that occur during the period around birth, is a major problem in developing countries accounting for more than one million stillbirths and a similar number of neonatal deaths worldwide each year [1,2]. A number of authors have emphasized that the time encompassing labor and the 24 hours after birth is the most dangerous period for both the mother and fetus/neonate [3]. To begin to focus attention on these deaths, several authors have created a new measure of pregnancy outcome-the sum of intrapartum stillbirths and early neonatal deaths >2500g, with the denominator all births >2500g [4]. This measure, which considers mortality to fetuses alive on admission to the health facility (often determined by Doptone) through discharge of the neonate, typically at 6 or 12 hours of age, is an important concept, since it is only during this time period that care in the facility can influence the outcome. By eliminating births likely to be preterm, this measure should count only those births with a reasonable likelihood of survival – if the obstetric and early neonatal care were good. As such, some authors have advocated using this measure as an indicator of the quality of obstetric care [4,5]. In the study reported here, the authors have included fresh stillbirth as a surrogate for an intrapartum fetal death and only asphyxia-related neonatal deaths instead of all early neonatal deaths [6]. Considering only births occurring at >35 weeks or >2000g is also similar to the proposed indicator which only counts births of 2500g or more. Thus, we believe the authors have developed an appropriate outcome to measure the quality of intrapartum care [6]. We have been impressed that the same obstetric conditions that kill mothers are also responsible for most of the stillbirths and many of the neonatal deaths as well [7]. These conditions include preeclampsia/eclampsia, obstructed labor and the associated infection and hemorrhage, obstetric hemorrhage from other causes and especially abruption, as well as obstetric risk factors such as growth restriction, fetal distress, malpositions, and multiple pregnancies. We emphasize that most of the precursors of stillbirth and many of the precursors of neonatal asphyxia are obstetric in origin. From our perspective, there are two ways to reduce the mortality and long term morbidity associated with asphyxia. One is to treat the asphyxiated infant in the postpartum period through a combination of neonatal resuscitation, ventilation and other supportive measures. However, potentially more important, is the prevention of antenatal and intrapartum asphyxia in the first place. Appropriate obstetrical care, both in the prenatal but especially in the intrapartum period, is crucial to reduce intrapartum stillbirth and neonatal asphyxia. For example, regular screening of all women in the antepartum period for preeclampsia with blood pressure measurements, with an appropriately timed delivery, can prevent progression to severe preeclampsia/eclampsia. Since most cases of eclampsia occur at or near term, an indicated delivery should reduce both stillbirth and neonatal asphyxia without significantly increasing neonatal deaths from prematurity. Similarly, screening for fetal growth restriction with delivery close to term will have similar results. Close monitoring and appropriate care during labor to enable obstetrical providers to recognize conditions such as prolonged labor, placental abruption, placental previa, fetal malposition, and fetal distress, can allow for rapid intervention with cesarean section, to further reduce rates of stillbirth and neonatal asphyxia. Reducing perinatal asphyxia on a population basis requires a heath system in which every woman is screened for the conditions discussed above and is provided care for those conditions in a timely fashion. Since many of the conditions progress rapidly during labor, advanced planning for the treatment is often helpful. Regular obstetric drills for conditions like eclampsia, severe hemorrhage, and fetal distress will allow the staff to practice for these emergency conditions, and make sure that when presented with these conditions, there are adequate equipment, medications and trained staff available so that both the mother and fetus are delivered safely. Perinatal death audits that evaluate both cause of death and potential for preventability are crucial to reduce preventable mortality. Finally, availability of sufficient staff and appropriate equipment to handle obstetric emergencies is crucial. Most important is the recognition that in order to reduce neonatal death and disability from intrapartum asphyxia, prevention and treatment of obstetrical conditions in the mother is better than resuscitation of an already asphyxiated infant. This paper is important because it focuses on the intrapartum factors related to perinatal asphyxia, and starts to address preventable causes [6]. Further work should evaluate methods to reduce perinatal asphyxia of obstetric origin.

OP14.08: First trimester screening for fetal growth restriction using Doppler and PAPP-A

OP14.08: First trimester screening for fetal growth restriction using Doppler and PAPP-A

Association of Uterine Artery Doppler Resistance Index and Birth Weight: Effect of Customized Birth Weight Standards

We assessed the effect of using customized birth-weight standards on the association of uterine artery Doppler resistance index (RI) and birth weight. This was a cross-sectional study of 2035 pregnancies scanned at 19 to 23 weeks. Both uterine arteries were identified using color flow mapping, and the RI was measured. The pregnancy outcome was obtained from the delivery suite database and the customized birth-weight centile calculated for each pregnancy. Both birth-weight and customized birth-weight centiles were converted to z-scores. The correlation of uterine artery RI with birth weight was examined using conventional and customized birth-weight standards. Conventional and customized birth weights showed a significant correlation with uterine artery RI ( R = -0.062 and -0.208, respectively). The correlation was significantly improved by the use of customized birth weight. Use of customized birth weight significantly improves the correlation of uterine artery RI and birth weight. This finding may partly explain the lower sensitivity of uterine artery Doppler screening for fetal growth restriction as compared with preeclampsia.

640: First trimester integrated screening for fetal growth restriction

Fetal growth restriction (FGR) is a high risk condition with considerable morbidity and mortality. Early prediction offers the possibility for prevention. It was the aim of our study to develop a first trimester predictive algorithm for FGR.

Screening for Fetal Growth Restriction

Since antenatal detection of fetal growth restriction, defined as birth weight <10% for gestational age, can reduce perinatal morbidity with antepartum testing and use of Doppler, it is imperative that there be a greater effort to detect the growth abnormality. According to a well-conducted randomized clinical trial, all uncomplicated pregnancies should have sonographic assessment of birth weight at 30-32 weeks and at 36-37 weeks. An increased awareness not only of the risk factors but also of the associated probability of abnormal growth can identify the cohorts that would benefit from uterine artery Doppler in 2nd trimester. Among patients at risk for suboptimal growth, Doppler of the umbilical artery improves the detection rate.

Symphysis-fundus height and pregnancy characteristics in ultrasound-dated pregnancies

Objective: To investigate the relation between maternal and pregnancy characteristics and symphysis-fundus height values at term in an obstetric population dated by sonography. Methods: Three hundred twenty-five women were recruited from the antenatal clinics of the Queen’s Medical Centre, Nottingham, United Kingdom for measurement of fundal height and for ultrasound scans. Symphysis-fundus height measurements were analyzed by multivariate regression analysis in relation to gestational age, maternal height and weight, ethnic group, and smoking. Results: Gestational age and maternal characteristics explained nearly half of the variability in symphysis-fundus height. Gestational age was the most important determinant, followed by maternal weight, parity, and sex of the infant. The other variables were not significantly correlated. Conclusion: Maternal characteristics had statistically significant effects on the expected symphysis-fundus height, which suggests that individually adjusted fundal height charts may improve the precision of clinical screening for fetal growth restriction.

Screening for Fetal Growth Restriction

In Brief Objective We estimated the effect of ultrasound error and time interval between examinations on the false-positive rate for detecting fetal growth restriction (FGR). Methods Using published growth curves for the fetal abdominal circumference and a coefficient of variation for ultrasound error of 5%, computer simulation was used to estimate false-positive rates in relation to the time interval between ultrasound examinations. Growth restriction was diagnosed when there was no apparent growth in fetal abdominal circumference between two consecutive examinations. In separate studies, the false-positive rate was plotted against gestational age at the first ultrasound examination. Results There was a dramatic increase in false-positive rates as the time interval between examinations was reduced. When the initial scan was performed at 32 weeks, the false-positive rate increased from 3.2% for an interval of 4 weeks to 30.8% for an interval of 1 week. At a 2-week interval, the error was 16.9%. There was a significant increase in the false-positive rate as the gestational age at the initial ultrasound was increased. At 28 weeks, the falsepositive rate with a 2-week interval was 11.8%, increasing to 24.1% at 38 weeks. By varying the coefficient of variation of the ultrasound error, the false-positive rate increased from 0.8% at an error of 2% to 31.9% at an error of 10%. Conclusion Ultrasound scanning at 2-week intervals is associated with false-positive rates for growth restriction in excess of 10%, increasing to much higher rates late in the third trimester. Improved screening performance should be attainable by increasing the interval between scans and reducing measurement errors. Screening for fetal growth restriction by ultrasound scans performed at 2-week intervals leads to false-positive diagnoses in more than 10% of cases.

Screening for fetal growth restriction: a mathematical model of the effect of time interval and ultrasound error

Objective: We estimated the effect of ultrasound error and time interval between examinations on the false-positive rate for detecting fetal growth restriction (FGR). Methods: Using published growth curves for the fetal abdominal circumference and a coefficient of variation for ultrasound error of 5%, computer simulation was used to estimate false-positive rates in relation to the time interval between ultrasound examinations. Growth restriction was diagnosed when there was no apparent growth in fetal abdominal circumference between two consecutive examinations. In separate studies, the false-positive rate was plotted against gestational age at the first ultrasound examination. Results: There was a dramatic increase in false-positive rates as the time interval between examinations was reduced. When the initial scan was performed at 32 weeks, the false-positive rate increased from 3.2% for an interval of 4 weeks to 30.8% for an interval of 1 week. At a 2-week interval, the error was 16.9%. There was a significant increase in the false-positive rate as the gestational age at the initial ultrasound was increased. At 28 weeks, the false-positive rate with a 2-week interval was 11.8%, increasing to 24.1% at 38 weeks. By varying the coefficient of variation of the ultrasound error, the false-positive rate increased from 0.8% at an error of 2% to 31.9% at an error of 10%. Conclusion: Ultrasound scanning at 2-week intervals is associated with false-positive rates for growth restriction in excess of 10%, increasing to much higher rates late in the third trimester. Improved screening performance should be attainable by increasing the interval between scans and reducing measurement errors.