Israel Medical Association Journal

Background: The sonographic assessment of estimated fetal weight (EFW) is essential for identification of fetuses in weight extremes and aids in peripartum management. However, there are inconsistent reports regarding EFW accuracy.

Objective: To examine maternal and fetal determinants associated with unreliable EFW.

Methods: A retrospective case-control study was conducted at a single, tertiary medical center between 2011 and 2019. All term, singleton deliveries with a sonographic EFW within 2 weeks of delivery were included. Unreliable EFW was defined as > 500 grams discordance between it and the actual birth weight. We allocated the study cohort into two groups: unreliable EFW (cases) and accurate EFW (controls).

Results: Overall, 41,261 deliveries met inclusion criteria. Of these, 1721 (4.17%) had unreliable EFW. The factors positively associated with unreliable EFW included body mass index > 30 kg/m², weight gain > 20 kg, higher amniotic fluid index, pregestational diabetes, gestational age > 41^0/7, and birth weight ≥ 4000 grams. On multiple regression analysis, pregestational diabetes (odds ratio [OR] 2.22, 95% confidence interval [95%CI] 1.56–3.17, P < 0.001) and a higher birth weight (OR 1.91, 95%CI 1.79–2.04, P < 0.001) were independently associated with unreliable EFW. On analysis of different weight categories, pregestational diabetes was associated with unreliable EFW only among birth weights ≥ 3500 grams (OR 3.28, 95%CI 1.98–5.44, P< 0.001) and ≥ 4000 grams (OR 4.27, 95%CI 2.31–7.90, P < 0.001).

Conclusion: Pregestational diabetes and increased birth weight are independent risk factors for unreliable EFW and should be considered when planning delivery management.

Background: Sonographic estimation of birth weight may differ among evaluators due to its operator-dependent nature.

Objectives: To compare the accuracy of estimation of fetal birth weight by sonography between ultrasound-certified physicians and registered diagnostic medical technicians.

Methods: The authors reviewed ultrasound examinations that had been performed by either technicians or ultrasound-certified obstetricians between 2010 and 2017, and within 2 days of delivery. Inclusion criteria were: singleton viable pregnancy, details of four ultrasound measurements (abdominal circumference, bi-parietal diameter, head circumference, and femur length), and known birth weight. The estimated fetal weight (EFW) was calculated according to the Hadlock formula, incorporating the four ultrasound measurements. The mean percentage error (MPE) was calculated by the formula: (EFW-birth weight) x100 / birth weight.

Results: Technicians performed 9741examinations and physicians performed 352 examinations. The proportion of macrosomic neonates was similar in both groups. Technicians were more accurate than physicians in terms of the MPE, absolute MPE, proportion of estimates that fell within ± 10% of birth weight, and Euclidean distance (P < 0.0001 for all comparisons). They were also more accurate in terms of sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating curve. Furthermore, for fetuses weighing more than 4000 grams the technicians had a lower total false prediction rate.

Conclusions: Medical technicians in our institute performed better than physicians in estimating fetal weight. Further studies are warranted to confirm our findings and better delineate the role of repeat physician’s examination after an initial estimation by an experienced technician.

Background: Two types of growth curves are commonly used to diagnose fetal growth disorders: neonatal birth weight (BW) and sonographic estimated fetal weight (EFW). The debate as to which growth curve to use is universal.

Objectives: To establish sonographic EFW growth curves for the Israeli population and to assess whether the use of the BW growth curves currently adapted in Israel leads to under-diagnosis of intrauterine growth disorders.

Methods: Biometric data collected during a 6 year period was analyzed to establish sonographic EFW growth curves between 15–42 weeks of gestation for the Israeli population. Growth curves were compared to previously published sonographic EFW growth curves. A comparison with the Israeli BW growth curves was performed to assess the possibility of under-diagnosis of intrauterine growth disorders.

Results: Out of 42,778 sonographic EFW studies, 31,559 met the inclusion criteria. The sonographic EFW growth curves from the current study resembled the EFW curves previously published. The comparison of the current sonographic EFW and BW growth curves revealed under-diagnosis of intrauterine growth disorders during the preterm period. Four percent of the fetuses assessed between 26–34 weeks would have been suspected of being growth restricted; 2.8 percent of the fetuses assessed between 30–36 weeks would have been suspected of having macrosomia, based on the BW growth curves.

Conclusions: New Israeli sonographic EFW growth curves resemble previously published sonographic EFW curves. Using BW growth curves may lead to the under-diagnosis of growth disorders. We recommend adopting sonographic EFW growth to diagnose intrauterine growth disorders.

Abstract

Parenteral nutrition (PN) must be initiated as soon as possible after delivery in very low birth weight (VLBW) preterm infants in order to prevent postnatal growth failure and improve neurodevelopmental outcome. When administered early, high levels of parenteral amino acids (AA) are well tolerated and prevent negative nitrogen balance. Although proteins are the driving force for growth, protein synthesis is energy demanding. Intravenous lipid emulsions (ILE) constitute a good energy source because of their high energy density and provide essential fatty acids (FA) along with their long-chain polyunsaturated fatty acid (LC-PUFA) derivatives necessary for central nervous system and retinal development. Early supply of ILE is not associated with increased morbidity. No significant differences were found between ILE based on soybean oil only and mixed ILE containing soybean oil in combination with other fat sources, except for a reduction in the incidence of sepsis with non-pure soybean ILE, and possibly less PN-associated liver disease with mixed ILE containing some fish oil. In preterm infants glucose homeostasis is still immature in the first days of life and abnormalities of glucose homeostasis are common. VLBW infants may not tolerate high levels of glucose infusion without hyperglycemia. Administering lower levels of glucose infusion as part of full early PN seems more successful than insulin at this stage. Postpartum there is a transition period when the water and electrolyte balance may be severely disturbed and should be closely monitored. Avoiding fluid overload is critical for preventing respiratory and other morbidities

Background: High frequency oscillatory ventilation based on optimal lung volume strategy is one of the accepted modes of ventilatory support for respiratory distress syndrome in very low birth weight infants. In 1999 it was introduced in our unit as the primary ventilation modality for RDS[1].

Objectives: To evaluate if the shift to HFOV[2] influenced the outcome of ventilated VLBW[3] infants in the neonatal intensive care unit of Carmel Medical Center.

Methods: Data were obtained from the medical charts of VLBW infants born at Carmel Medical Center, and late mortality data were taken from the Israel Ministry of Internal Affairs records. A retrospective analysis and a comparison with a historical control group ventilated by the conventional method were performed.

Results: A total of 232 VLBW infants with RDS were mechanically ventilated, from 1995 to 2003: 120 were ventilated using HFOV during the period 1999–2003 and 102 infants using CV[4] during 1995–1999. The mean gestational age of survivors was 27.4 ± 2 weeks in the HFOV group and 28.4 ± 2 in the conventional ventilation group (P = 0.03). The sub-sample of infants with birth weights <1000 g ventilated with HFOV showed higher survival rates than the infants in the conventional ventilation group, 53 vs. 25 (64.6% vs. 44.6%) respectively (P < 0.05). A trend for lower incidence of pulmonary interstitial emphysema was observed in the HFOV group.

Conclusions: The introduction of HFOV based on optimal lung volume strategy proved to be an efficient and safe method of ventilation support for VLBW infants in our unit.

Background: The incidence of congenital heart defects, reported to be 5–8/1000 in term infants, is not well established in very low birth weight infants.

Objectives: To establish the incidence of congenital heart defects in VLBW[1] infants in the neonatal intensive care unit of our institution.

Methods: A retrospective analysis of the population in the NICU[2] at our institution was performed. VLBW (BW ≤ 1500 g) infants born between 2001 and 2006 who survived more than 48 hours were included in the study. Infants with clinical signs of heart disease underwent echocardiography.

Results: During the study period 437 VLBW live-born infants met the inclusion criteria. Of these, 281 (64.3 %) underwent echocardiography. CHD[3] was detected in 19 infants (4.4%, 95% confidence interval 2.4–5.4%), significantly higher than the incidence of 5–8/1000 in the general population (P < 0.0001). In the subgroup of 154 infants with BW < 1000 g there were 10 (6.5%) with CHD. In the subgroup of 283 infants with BW 100–-1500 g there were 9 (3.2 %, P = 0.19 vs. VLBW) with CHD.

Conclusions:  Our observations show an increased incidence of CHD in VLBW neonates, as compared to the general population. Since not all infants underwent echocardiography, and minor cardiac defects may have been missed in our VLBW infants, the true incidence may be higher than reported here.

Background: A substantial number of premature deliveries occur in hospitals lacking neonatal intensive care facilities. We previously demonstrated a comparable outcome of very low birth weight infants delivered in a level II nursery to that of inborn infants delivered in our tertiary care center, but a similar comparison of extremely low birth weight infants has not been done.

Objectives: To compare the neonatal outcome (mortality, severe intraventricular hemorrhage/periventricular leukomalacia, bronchopulmonary dysplasia and intact survival) of inborn and outborn ELBW[1] infants, accounting for sociodemographic, obstetric and perinatal variables.

Methods: We compared 97 ELBW infants (birth weight ≤ 1000 g.) delivered between the years 2000 and 2004 in a hospital providing neonatal intensive care to 53 ELBW babies delivered in a referring hospital. A univariate model was first applied to examine the associations of the individual independent variables with the outcome variable, followed by a logistic stepwise regression analysis for each of the outcome variables. The odds ratios for each predictor were reported as well as their P values and 95% confidence intervals.

Results: In the stepwise logistic regression analysis, accounting for a possible confounding effect of the independent variables, ‘hospital of birth’ remained a statistically significant predictor in the final step only for mortality, with odds ratio (inborns relative to outborns) of 3.32 (95%CI[2] 1.19–9.28, P = 0.022). No statistically significant associations with the other outcome variables were found (severe IVH[3]/PVL[4] odds ratio = 1.99, 95%CI = 0.77–5.14, P = 0.155; BPD[5] odds ratio = 0.60, 95%CI = 0.19–1.91, P = 0.384; intact survival OR[6] = 0.56, 95%CI = 0.23–1.35, P = 0.195).

Background: Many centers in Israel still use pre-1970 reference data for neonatal weight, length and head circumference. A recently published population-based reference overestimated the weight of premature infants.

Objective: To develop a national reference for birth weight, birth length, and head circumference by gestational age for singleton infants in Israel.

Methods: Data were collected on all singleton live births documented in the neonatal registry of Rabin Medical Center from 1991 to 2005 (n=82,066). Gestational age estimation was based on the last menstrual period until 1977 and early fetal ultrasound thereafter. Neonates with an implausible birth weight for gestational age (identified by the rule of median ± 5 standard deviations or expert clinical opinion) were excluded. Reference tables for fetal growth by gestational age were created for males and females separately.

Results: The growth references developed differed markedly from the Usher curves currently used in our department. Compared to the recently published population-based birth weight reference, our data were free of the problem of differential misclassification of birth weight for gestational age for the premature infants and very similar for the other gestational age groups. This finding reinforced the validity of our measurements of birth weight, as well as of birth length and head circumference.

Conclusions: Use of our new (birth length and head circumference) and improved (birth weight) gender-specific hospital-based reference for fetal growth may help to define normal and abnormal growth in the neonatal population of Israel and thereby improve neonatal care and public health comparisons.
 

Background: Babies born with extreme prematurity and low birth weight (< 1000 g) present a unique treatment challenge. In addition to the complexity of achieving survival, they may require surgical interventions for abdominal emergencies. Usually, these infants are transferred to a referral center for surgery treatment. Since 2000 our approach is bedside abdominal surgery at the referring center.

Objectives: To evaluate whether the approach of bedside abdominal surgery at the referring center is safe and perhaps even beneficial for the baby.

Methods: We retrospectively reviewed our data since 2000 and included only babies weighing < 1000 g who were ventilated, suffered from hemodynamic instability and underwent surgery for perforated bowel at the referring neonatal unit. Results were analyzed according to survival from the acute event (> 1 week), survival from the abdominal disease (> 30 days) and survival to discharge.

Results: Twelve babies met the inclusion criteria. Median weight at operation was 850 g (range 620–1000 g) and median age at birth was 25 weeks (range 23–27). Eleven infants survived the acute event (91.7%), 9 survived more than 30 days (81.8%), and 5 survived to discharge.

Conclusions: Our results show that bedside laparotomy at the referring hospital is safe and feasible. A larger randomized study is indicated to prove the validity of this approach.

Background: A paradoxical secular trend of an increase in preterm births and a decrease in low birth weights has been reported in many developed countries over the last 25 years.

Objective: To determine if this trend is true for Israeli neonates, and to add new information on secular trends in crown-heel length and head circumference.

Methods: A hospital-based historic cohort design was used. Anthropometric data for 32,062 infants born at Rabin Medical Center in 1986–1987, 1994–1996, and 2003–2004 were collected from the hospital’s computerized registry and compared over time for absolute values and proportional trends.

Results: For the whole sample (gestational age 24–44 weeks) there was a significant increase in mean birth weight (by 41 g), crown-heel length (by 1.3 cm), and head circumference (by 0.1 cm) from 1986 to 2004 (P < 0.001). A similar trend was found on separate analysis of the post-term babies. Term infants showed an increase in mean length and head circumference (P < 0.001), but not weight, and moderately preterm infants (33–36 weeks) showed an increase in mean weight (81 g, P < 0.001) and mean length (1.0 cm, P < 0.001), but not head circumference. The proportion of post-term (42–44 weeks), preterm (24–36 weeks), very preterm (29–32 weeks), extremely preterm (24–28 weeks), low birth weight (< 2500 g) and very low birth weight (< 1500 g) infants decreased steadily and significantly over time (P < 0.002).

Conclusions: Babies born in our facility, term and preterm, are getting bigger and taller. This increase is apparently associated with a drop (not a rise) in the proportion of preterm infants. These results might reflect improvements in antenatal care and maternal determinants.
 

Background: Necrotizing enterocolitis is a common progressive gastrointestinal disease affecting more than 5% of very low birth weight infants and associated with a high mortality rate.

Objectives: To determine whether excessive weight gain in preterm infants is an early sign of NEC[1].

Methods: Seventeen preterm infants with perforated NEC were identified and matched with 17 control subjects for birth weight and gestational age. The postnatal age (days) at diagnosis of NEC was identified, and weight changes as well as clinical and laboratory data were recorded and compared for 7 days prior through 7 days post-diagnosis.

Results: A significant difference in weight gain was noticed between D-1 and D 0. The NEC and control groups gained 5.1% and 1.2%, respectively (P = 0.002). None of the sick infants lost weight on days -1 to D 0.

Conclusions: Excessive weight gain was observed in premature infants who subsequently developed NEC. Daily evaluation of weight changes should be considered part of a strategy for early identification of infants at risk for developing NEC. Future studies are needed to confirm this finding in a prospective manner and to investigate its pathogenesis.

Objectives: To compare the neonatal outcome (survival, intraventricular hemorrhage and bronchopulmonary dysplasia) of inborn and outborn very low birth weight infants, accounting for sociodemographic, obstetric and perinatal variables, with reference to earlier published data.

Methods: We compared 129 premature infants with birth weights of 750–1250 g delivered between 1996 and 2000 in a hospital providing neonatal intensive care to 99 premature babies delivered in a referring hospital. In the statistical analysis, variables with a statistical significant association with the outcome variables and dissimilar distribution in the two hospitals were identified and entered together with the hospital of birth as explanatory variables in a logistic regression.

Results: Accounting for the covariates, the odds ratios (outborns relative to inborns) were 0.31 (95% confidence interval = 0.11–0.86, P = 0.03) for mortality, 1.37 (95%CI[1] = 0.64–2.96, P = 0.42) for severe intraventricular hemorrhage, and 0.86 (95%CI = 0.38–1.97, P = 0.78) for bronchopulmonary dysplasia. The odds ratio for survival without severe intraventricular hemorrhage was 1.10 (95%CI = 0.55–2.20, P = 0.78). Comparing the current results with earlier (1990–94) published data from the same institution showed that mortality decreased in both the outborn and inborn infants (OR[2] = 0.23, 95%CI = 0.09–0.58, P = 0.002 and 0.46; 95%CI = 0.20–1.04, P = 0.06, respectively), but no significant change in the incidence of severe intraventricular hemorrhage or brochopulmonary dysplasia was observed. Increased survival was observed also in these infants receiving surfactant, more so among the outborn. The latter finding could be attributed to the early, pre-transport surfactant administration, implemented only during the current study.

Conclusions: Our data suggest that very low birth weight outborn infants may share an outcome comparable with that of inborn babies, if adequate perinatal care including surfactant administration is provided prior to transportation to a tertiary center.

Objective: To establish population-based standards of birth weight of singletons in Israel.

Methods: Data on birth weight and gestational age were obtained from the registries of the Israel Ministry of Health and Ministry of the Interior. During the 8 year study period there were 1,074,122 infants delivered in Israel; 787,710 (73%) were included in this analysis.

Results: In this study we provide data of birth weight by gestational age of live infants born in Israel between 1993 and 2001. Ranges of birth weight by gestational age are also depicted for singleton and multiple pregnancies. Fetuses in multiple pregnancies grow in a similar manner to singletons until 30 weeks of gestation, after which their growth slows down.

Conclusions: Use of these data as a standard for “intrauterine” growth better represents the Israeli neonatal population than the American standards. In addition, curves of multiple pregnancies are significantly different from those of singleton pregnancies and might be more appropriate in these pregnancies.