Fetal biometry: does patient ethnicity matter?

Midtrimester isolated short femur and perinatal outcomes: A systematic review and meta-analysis

INTRODUCTION

Fetal femur length below the expected value has been described as a marker of aneuploidy, skeletal dysplasia, intrauterine growth restriction and small-for-gestational-age neonate. The aim of this systematic review and meta-analysis was to evaluate the strength of association between isolated short femur length and intrauterine growth restriction or small-for-gestational-age, and perinatal adverse outcomes.

MATERIAL AND METHODS

PubMed, EMBASE and Medline were searched from the inception of each database to May 2018. Selection criteria included prospective and retrospective cohort studies of singleton pregnancies between 18 and 28 weeks of gestation, with sonographic finding of isolated short femur length, without any structural chromosomal abnormality. The meta-analysis was performed by computing odds ratios using both fixed and random-effects models. Quality assessment of the included studies was performed using the Newcastle-Ottawa Scale.

RESULTS

Six studies including 3078 cases of isolated short femur length (study group) and 222 303 normal femur length (control group) were included. The prevalence of intrauterine growth restriction or small-for-gestational-age in the study group was 14.2%, compared with 5.2% in the control group (odds ratio of 4.04, 95% confidence interval 3.63-4.50). Isolated short femur length was associated with a higher incidence of low birthweight (study group: 22.10% vs control group: 8.57%, odds ratio 3.24, 95% confidence interval 2.34-4.48), Apgar <7 at 5 minutes (study group: 3.98% vs control group: 1.79%, odds ratio 3.56, 95% confidence interval 1.87-6.77), preterm birth (study group: 12.16% vs control group: 8.16%, odds ratio 3.09, 95% confidence interval 1.57-6.08), fetal death (study group: 1.83% vs control group: 0.44%, odds ratio 6.48, 95% confidence interval 3.70-11.35) and neonatal intensive care unit admission (study group: 15.34% vs control group: 14.81%, odds ratio 2.11, 95% confidence interval 0.56-7.93).

CONCLUSIONS

There is a significant association between isolated short femur length and intrauterine growth restriction or small-for-gestational-age and poor perinatal outcome.

Fetal Biometric Charts and Reference Equations for Pregnant Women Living in Port Said and Ismailia Governorates in Egypt

AIM:

To construct new fetal biometric charts and equations for some fetal biometric parameters for women between 12^th and 41^st weeks living in Ismailia and Port Said Governorates in Egypt.

MATERIAL AND METHODS:

This cross-sectional study was carried out on 656 Egyptian women (from Ismailia and Port Said governorates) with an uncomplicated pregnancy, and all were sure of their dates. The selected group was between the 12^th and 41^st weeks of gestation, recruited from the district general hospital in Ismailia and Port Said to measure ultrasonographically biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL), then for each measurement separate regression models were fitted to estimate both the mean and the Standard deviation at each gestational age.

RESULTS:

New Egyptian charts were reported for BPD, HC, AC, and FL. Reference equations for the dating of pregnancy were presented. The mean of the previous measurements at 12^th and 41^st weeks were as follows: (23.37, 98.72), (83.05, 336.12), (67.85, 332.57) and (12.50, 74.92) respectively.

CONCLUSION:

New fetal biometric charts and regression equations for pregnant women living in Port Said & Ismailia governorates in Egypt.

Evidence-based national guidelines for the management of suspected fetal growth restriction: comparison, consensus, and controversy

Small for gestational age is usually defined as an infant with a birthweight <10th centile for a population or customized standard. Fetal growth restriction refers to a fetus that has failed to reach its biological growth potential because of placental dysfunction. Small-for-gestational-age babies make up 28-45% of nonanomalous stillbirths, and have a higher chance of neurodevelopmental delay, childhood and adult obesity, and metabolic disease. The majority of small-for-gestational-age babies are not recognized before birth. Improved identification, accompanied by surveillance and timely delivery, is associated with reduction in small-for-gestational-age stillbirths. Internationally and regionally, detection of small for gestational age and management of fetal growth problems vary considerably. The aim of this review is to: summarize areas of consensus and controversy between recently published national guidelines on small for gestational age or fetal growth restriction; highlight any recent evidence that should be incorporated into existing guidelines; and identify future research priorities in this field. A search of MEDLINE, Google, and the International Guideline Library identified 6 national guidelines on management of pregnancies complicated by fetal growth restriction/small for gestational age published from 2010 onwards. There is general consensus between guidelines (at least 4 of 6 guidelines in agreement) in early pregnancy risk selection, and use of low-dose aspirin for women with major risk factors for placental insufficiency. All highlight the importance of smoking cessation to prevent small for gestational age. While there is consensus in recommending fundal height measurement in the third trimester, 3 specify the use of a customized growth chart, while 2 recommend McDonald rule. Routine third-trimester scanning is not recommended for small-for-gestational-age screening, while women with major risk factors should have serial scanning in the third trimester. Umbilical artery Doppler studies in suspected small-for-gestational-age pregnancies are universally advised, however there is inconsistency in the recommended frequency for growth scans after diagnosis of small for gestational age/fetal growth restriction (2-4 weekly). In late-onset fetal growth restriction (≥32 weeks) general consensus is to use cerebral Doppler studies to influence surveillance and/or delivery timing. Fetal surveillance methods (most recommend cardiotocography) and recommended timing of delivery vary. There is universal agreement on the use of corticosteroids before birth at <34 weeks, and general consensus on the use of magnesium sulfate for neuroprotection in early-onset fetal growth restriction (<32 weeks). Most guidelines advise using cardiotocography surveillance to plan delivery in fetal growth restriction <32 weeks. The recommended gestation at delivery for fetal growth restriction with absent and reversed end-diastolic velocity varies from 32 to ≥34 weeks and 30 to ≥34 weeks, respectively. Overall, where there is high-quality evidence from randomized controlled trials and meta-analyses, eg, use of umbilical artery Doppler and corticosteroids for delivery <34 weeks, there is a high degree of consistency between national small-for-gestational-age guidelines. This review discusses areas where there is potential for convergence between small-for-gestational-age guidelines based on existing randomized controlled trials of management of small-for-gestational-age pregnancies, and areas of controversy. Research priorities include assessing the utility of late third-trimester scanning to prevent major morbidity and mortality and to investigate the optimum timing of delivery in fetuses with late-onset fetal growth restriction and abnormal Doppler parameters. Prospective studies are needed to compare new international population ultrasound standards with those in current use.

Fetal biometric parameters: Reference charts for a non-selected risk population from Uberaba, Brazil

OBJECTIVE

To establish reference charts for fetal biometric parameters in a non-selected risk population from Uberaba, Southeast of Brazil.

METHODS

A retrospective cross-sectional study was performed among 5656 non-selected risk singleton pregnant women between 14 and 41 weeks of gestation. The ultrasound exams were performed during routine visits of second and third trimesters. Biparietal diameter (BPD) was measured at the level of the thalami and cavum septi pellucidi. Head circumference (HC) was calculated by the following formula: HC = 1.62*(BPD + occipital frontal diameter, OFD). Abdominal circumference (AC) was measured using the following formula: AC = (anteroposterior diameter + transverse abdominal diameter) × 1.57. Femur diaphysis length (FDL) was obtained in the longest axis of femur without including the distal femoral epiphysis. The estimated fetal weight (EFW) was obtained by the Hadlock formula. Polynomial regressions were performed to obtain the best-fit model for each fetal biometric parameter as the function of gestational age (GA).

RESULTS

The mean, standard deviations (SD), minimum and maximum of BPD (cm), HC (cm), AC (cm), FDL (cm) and EFW (g) were 6.9 ± 1.9 (2.3 - 10.5), 24.51 ± 6.61 (9.1 - 36.4), 22.8 ± 7.3 (7.5 - 41.1), 4.9 ± 1.6 (1.2 - 8.1) and 1365 ± 1019 (103 - 4777), respectively. Second-degree polynomial regressions between the evaluated parameters and GA resulted in the following formulas: BPD = -4.044 + 0.540 × GA - 0.0049 × GA² (R² = 0.97); HC= -15.420 + 2.024 GA - 0.0199 × GA² (R² = 0.98); AC = -9.579 + 1.329 × GA - 0.0055 × GA² (R² = 0.97); FDL = -3.778 + 0.416 × GA - 0.0035 × GA² (R² = 0.98) and EFW = 916 - 123 × GA + 4.70 × GA² (R² = 0.96); respectively.

CONCLUSION

Reference charts for the fetal biometric parameters in a non-selected risk population from Uberaba, Southeast of Brazil, were established.

Unconditional and conditional standards for fetal abdominal circumference and estimated fetal weight in an ethnic Chinese population: a birth cohort study

BACKGROUND

Diagnosis of intrauterine fetal growth restriction and prediction of small-for-gestation age are often based on fetal abdominal circumference or estimated fetal weight (EFW). The present study aims to create unconditional (cross-sectional) and conditional (longitudinal) standards of fetal abdominal circumference and EFW for use in an ethnic Chinese population.

METHODS

In the Growing Up in Singapore Towards healthy Outcome (GUSTO) birth cohort study in Singapore, fetal biometric measurements were obtained at enrolment to antenatal care (11-12 weeks) and up to three more time points during pregnancy. Singleton pregnancies with a healthy profile defined by maternal, pregnancy and fetal characteristics and birth outcomes were selected for this analysis. The Hadlock algorithm was used to calculate EFW. Mixed effects model was used to establish unconditional and conditional standards in z-scores and percentiles for both genders pooled and for each gender separately.

RESULTS

A total of 313 women were included, of whom 294 had 3 and 19 had 2 ultrasound scans other than the gestational age dating scan. Fetal abdominal circumference showed a roughly linear trajectory from 18 to 36 weeks of gestation, while EFW showed an accelerating trajectory. Gender differences were more pronounced in the 10(th) percentile than the 50(th) or 90(th) percentiles. As compared to other published charts, this population showed growth trajectories that started low but caught up at later gestations.

CONCLUSIONS

Unconditional and conditional standards for monitoring fetal size and fetal growth in terms of abdominal circumference and EFW are available for this ethnic-Chinese population. Electronic spreadsheets are provided for their implementation.