Selection of Standards for Sonographic Fetal Head Circumference by Use of z-Scores.

OBJECTIVE: This study aimed to evaluate which of five established norms should be used for sonographic assessment of fetal head circumference (HC). STUDY DESIGN: Cross-sectional study using pooled data from four maternal-fetal medicine practices. Inclusion criteria were singleton fetus, gestational age 220/7 to 396/7 weeks, biometry measured, and fetal cardiac activity present. Five norms of HC were studied: Jeanty et al, Hadlock et al, the INTERGROWTH-21st Project (IG-21st), the World Health Organization Fetal Growth Curves (WHO), and the National Institutes of Child Health and Human Development Fetal Growth Studies unified standard (NICHD-U). The fit of our HC measurements to each norm was assessed by these criteria: mean z-score close to 0, standard deviation (SD) of z close to 1, low Kolmogorov-Smirnov D-statistic, high Youden J-statistic, close to 10% of exams >90th percentile, close to 10% of exams <10th percentile, and close to 2.28% of exams >2 SD below the mean. RESULTS: In 23,565 ultrasound exams, our HC measurements had the best fit to the WHO standard (mean z-score 0.10, SD of z = 1.01, D-statistic <0.01, J-statistic 0.83-0.94). The SD of the Jeanty reference was much larger than all the other norms and our measurements, resulting in underdiagnosis of abnormal HC. The means of the IG-21st and NICHD-U standards were smaller than the other norms and our measurements, resulting in underdiagnosis of small HC. The means of the Hadlock reference were larger than all the other norms and our measurements, resulting in overdiagnosis of small HC. Restricting the analysis to a low-risk subgroup of 4,423 exams without risk factors for large- or small-for-gestational age produced similar results. CONCLUSION: The WHO standard is likely best for diagnosis of abnormal HC. The Jeanty (Chervenak) reference suggested by the Society for Maternal-Fetal Medicine had poor sensitivity for microcephaly screening. KEY POINTS: · There are >30 norms for fetal HC.. · It is unknown which norm should be used.. · The WHO standard fits our data best.. · The Chervenak reference is not sensitive for microcephaly..

Routine third-trimester ultrasound in low-risk pregnancies and perinatal death: a systematic review and meta-analysis.

OBJECTIVE: This study aimed to determine whether routine third-trimester ultrasounds in low-risk pregnancies decrease the rate of perinatal death compared with regular antenatal care with serial fundal height measurements. DATA SOURCES: This was a systematic review and meta-analysis of randomized control trials to identify relevant studies published from inception to October 2019. The databases used were Ovid, PubMed, Scopus, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials using a combination of key words related to "third trimester ultrasound" and "low-risk." STUDY ELIGIBILITY CRITERIA: We included all randomized control trials of singleton, nonanomalous low-risk pregnancies that were randomized to either one or more third-trimester ultrasounds (ultrasound group) or serial fundal height (fundal height group). Exclusion criteria were patients with multiple gestations, maternal medical complications, or fetal abnormalities requiring a third-trimester ultrasound. STUDY APPRAISAL AND SYNTHESIS METHODS: The primary outcome was the rate of perinatal death. The secondary outcomes were rates of fetal growth restriction, suspected large for gestational age, polyhydramnios, oligohydramnios, fetal anomalies, antenatal interventions, stillbirth, neonatal death, cesarean delivery, induction of labor, and other neonatal outcomes. This meta-analysis was performed with the use of the random effects model of DerSimonian and Laird to produce relative risk or mean difference with a corresponding 95% confidence interval. RESULTS: A total of 7 randomized control trials with 23,643 participants (12,343 in the ultrasound group vs 11,300 in the fundal height group) were included. The total rate of perinatal death was similar among the groups (41 of 11,322 [0.4%] vs 34 of 10,285 [0.3%]; relative risk, 1.14; 95% confidence interval, 0.68-1.89). The rate of fetal growth restriction was higher in the ultrasound group (763 of 10,388 [7%] vs 337 of 9021 [4%]; relative risk, 2.11; 95% confidence interval, 1.86-2.39) and the rate of suspected large for gestational age (1060 of 3513 [30%] vs 375 of 3558 [11%]; relative risk, 2.84; 95% confidence interval, 2.6-3.2). Polyhydramnios was also significantly higher in the ultrasound group than the fundal height group (18 of 323 [6%] vs 4 of 322 [1%] relative risk, 3.93; 95% confidence interval, 1.4-11). The rates of the remainder of the secondary outcomes were similar among the groups. CONCLUSION: Routine third-trimester ultrasounds do not decrease the rate of perinatal death compared with serial fundal height in low-risk pregnancies. Ideally, an adequately powered trial is warranted to determine whether perinatal mortality in the fundal height group can be reduced by one-third with third-trimester ultrasound.

Preterm Preeclampsia with Severe Features: Composite Maternal and Neonatal Morbidities Associated with Fetal Growth Restriction.

OBJECTIVE: The objective of this study was to compare adverse pregnancy outcomes between fetuses with estimated fetal weight (EFW) < 10 to > 10% in women with preterm preeclampsia (PE) with severe features. MATERIALS AND METHODS: All women with preterm PE with severe features and nonanomalous singletons with EFW were identified at a tertiary center. Women with oligohydramnios or absent/reversed umbilical Doppler velocimetry were excluded. Using multivariable analysis, we compared the composite maternal and neonatal morbidities (CMM and CNM) between those with appropriate for gestational age (AGA) fetal growth, defined as EFW at 10 to 90th versus those with fetal growth restriction (FGR), defined as EFW < 10th percentile for gestational age (GA). RESULTS: In this study, 165 patients were included; 112 had EFW at 10th to 90th percentile, and 53 had FGR. Of the 53 with FGR, 33 (62%) had EFW at 5 to 9% for GA and 20 (38%) had EFW < fifth percentile for GA. The CMM was significantly higher among women with FGR versus AGA (29 vs. 7%; p < 0.001). The CNM was significantly higher with FGR versus AGA (20 vs. 6%; p = 0.01). CONCLUSION: Women with preterm PE with severe features and FGR, when compared with those with AGA, have significantly higher risk of CMM and CNM.