Different formulas, different thresholds and different performance-the prediction of macrosomia by ultrasound.

OBJECTIVE: The sonographic prediction of fetal macrosomia affects obstetrical decision regarding the timing and mode of delivery. We aimed to compare the accuracy of various formulas for prediction of macrosomia at different thresholds. STUDY DESIGN: This was a retrospective cohort study of singleton gestations at term, with fetal biometrical measurements taken up to 7 days prior to delivery (2007 to 2014). Sonographic estimated fetal weight was calculated using 20 previously published formulas. Macrosomia prediction was evaluated for every formula utilizing: (1) measures of accuracy (sensitivity, specificity and so on); (2) comparison of the systematic and random errors (SE and RE), and the proportion of estimates within 10% of actual birth weight for macrosomic and non-macrosomic neonates. Performance measurements were evaluated for different macrosomia thresholds: 4000, 4250 and 4500 g. Best performing formula for every threshold was defined as the one with the lowest Euclidean distance (=SQRT(SE2+RE2)). RESULTS: Out of 7977 women who met the inclusion criteria, 754 (9.4%) delivered a neonate weighing ⩾4000 g, 266 (3.3%) delivered a neonate weighing⩾4250 g and 75 (0.9%) delivered a neonate weighing⩾4500 g. Considerable variability was noted between the accuracy parameters of the different formulas, with Woo's formula integrating Abdominal circumference (AC) and femur length (FL) as the most sensitive formula with the highest negative predictive value for all thresholds and Woo's formula using AC, FL and biparietal diameter (BPD) as the most specific for all thresholds. The same formula also demonstrated the best overall accuracy. Regardless of threshold chosen, 80% or more of formulas demonstrated negative systematic error, meaning lower EFW than actual birthweight. As for the Euclidean distance, Hadlock's formula (AC, FL and BPD) ranked the highest for the 4000 and 4250 g thresholds, whereas Shepard's formula (AC and BPD) ranked the highest for the 4500 g threshold. CONCLUSION: Considerable variability exist between formulas for prediction of neonatal macrosomia. Formulas by Hadlock's and Shepard's utilizing AC, BPD±FL were most accurate for macrosomia prediction at 4000, 4250 and 4500 g thresholds, respectively.

Maternal and neonatal demographics of macrosomic infants admitted to the neonatal intensive care unit.

OBJECTIVE: The objective of this study is to determine the incidence, significance, associated demographics and impact of macrosomic infants (⩾4 kg) admitted to the Neonatal Intensive Care Unit (NICU) on NICU census and resources. STUDY DESIGN: A retrospective cohort review was performed from 2010 to 2015. Descriptive statistical analyses were used. RESULTS: Of 19 308 deliveries, 1823 were infants ⩾4000 g and 213 were admitted to the NICU. Cesarean delivery occurred in 70% of the admitted infants, most (74.1%) were Grade 1 macrosomia and male (63%). Preterm birth occurred in 4%. The incidence of maternal diabetes was 25%. Primary admitting diagnoses were respiratory distress, suspected sepsis, hypoglycemia and perinatal depression. The average length of stay was 8±6 days for all macrosomic infants admitted, increased to 22±13 days for infants with Grade 3 macrosomia. CONCLUSION: Macrosomic infants are a growing population, who increase the demand on existing NICU resources. A larger multi-centered study is needed to determine the overall relevance of these findings in other populations.

High birth weight in a suburban hospital in Cameroon: an analysis of the clinical cut-off, prevalence, predictors and adverse outcomes.

BACKGROUND AND AIMS: High birth weight (HBW) increases the risk of maternal and fetal morbidity and mortality. Its prevalence and adverse outcomes may be reduced if risk factors are identified and managed during pregnancy. The cut-off value for HBW remains debatable. The objectives of this study were to identify the optimal cut-off value and determine the prevalence, predictors and adverse outcomes of HBW in a suburban area of Cameroon. DESIGN: A 6-year retrospective register analysis and a 3-month prospective phase. SETTING: A secondary care level (regional) hospital in the city of Buea (southwest region of Cameroon). PARTICIPANTS: Women who delivered in this hospital over a 6-year period (retrospective phase) and consenting pregnant mothers and their infants (singletons, born at >28 weeks gestation) (prospective phase). OUTCOME MEASURES: 90th centile of birth weights; prevalence of HBW defined as birth weight above the 90th centile; sociodemographic, maternal and obstetrical factors associated with HBW; maternal and neonatal adverse outcomes of HBW. RESULTS: Of the 4941 newborns reviewed in registers, the 90th centile of birth weights was 3850 g. Using this new cut-off, we obtained a prevalence of 14.0% for HBW in the 200 newborns included in the prospective phase. This was significantly higher than the prevalence (9.5%) yielded when the traditional cut-off of 4000 g was used (p=0.003). None of the factors assessed was independently associated with HBW. Newborns with HBW were more likely to have shoulder dystocia (p<0.01), and their mothers more likely to suffer from prolonged labour (p=0.01) and postpartum haemorrhage (p<0.01). CONCLUSIONS: The results of this study suggest that the cut-off for HBW in this population should be 3850 g. Thus, 3 of every 10 babies born with HBW in this hospital are likely not receiving optimal postnatal care because 4000 g is currently used to qualify for additional support.

An Evidence-Based Approach to Defining Fetal Macrosomia.

OBJECTIVE: This study aims to determine the risk of adverse outcomes associated with the current diagnostic criteria for fetal macrosomia. Study DESIGN: We evaluated three techniques for characterizing birth weight as a predictor of shoulder dystocia or third- or fourth-degree laceration in 79,879 vaginal deliveries. First, we compared deliveries with birth weights above or below 4,500 g. We then performed logistic regression using birth weight as a continuous predictor, both with and without fractional polynomial transformation. Finally, we calculated the number of cesarean sections required to prevent one incident of the interrogated outcomes (number needed to treat [NNT]). RESULTS: Rates of adverse intrapartum outcomes increase incrementally with increasing birth weight and are predicted most accurately with logistic regression following fractional polynomial transformation. The NNT for third- or fourth-degree laceration dropped from 14.3 (95% confidence interval [CI], 13.9-14.7) at a birth weight of 3,500 g to 6.4 (95% CI, 6.1-6.8) at 4,500 g and, for shoulder dystocia, from 54.9 (95% CI, 51.5-58.6) at 3,500 g to 5.6 (95% CI, 5.2-6.0) at 4,500 g. CONCLUSION: The conventional distinction between "normal" and "macrosomic" does not reflect the incremental effect of increasing birth weight on the risk of obstetric morbidity. Outcomes analysis can inform fetal growth standards to better reflect relevant thresholds of risk.