Newborn weight charts underestimate the incidence of low birthweight in preterm infants

Predictive performance of newborn small for gestational age by a United States intrauterine vs birthweight-derived standard for short-term neonatal morbidity and mortality

BACKGROUND

The use of birthweight standards to define small for gestational age may fail to identify neonates affected by poor fetal growth as they include births associated with suboptimal fetal growth.

OBJECTIVE

This study aimed to compare intrauterine vs birthweight-derived standards to define newborn small for gestational age to predict neonatal morbidity and mortality.

STUDY DESIGN

This was a secondary analysis of a multicenter observational study of 118,422 births. Live-born singleton, nonanomalous newborns born at 23 to 41 weeks of gestation were included. Those with missing gestational age estimation or without a first- or second-trimester ultrasound to confirm dating, birthweight, or neonatal outcome data were excluded. Birthweight percentile was computed using an intrauterine standard (Hadlock) and a birthweight-derived standard (Olsen). We compared the test characteristics of small for gestational age (birthweight of <10th percentile) by each standard to predict a composite neonatal morbidity and mortality outcome (death before discharge, neonatal intensive care unit admission >48 hours, respiratory distress syndrome, sepsis, necrotizing enterocolitis, grade 3 or 4 intraventricular hemorrhage, or seizures). Severe composite morbidity was analyzed as a secondary outcome and was defined as death, neonatal intensive care unit admission >7 days, necrotizing enterocolitis, grade 3 or 4 intraventricular hemorrhage, or seizures. The areas under the curve using receiver-operating characteristic methodology and proportions of the primary outcome by small for gestational age status were compared by gestational age category at birth (<34, 34 0/7 to 36 6/7, ≥37 weeks).

RESULTS

Of 115,502 mother-newborn dyads in the parent study, 78,203 (67.7%) were included, with most exclusions occurring because of missing or inadequate dating information, multiple gestations, or delivery outside the gestational age range. The primary composite outcome occurred in 9.5% (95% confidence interval, 9.3-9.7), and the severe composite outcome occurred in 5.3% (95% confidence interval, 5.1-5.4). Small for gestational age was diagnosed by intrauterine and birthweight-derived standards in 14.8% and 7.4%, respectively (P<.001). Neonates considered small for gestational age only by the intrauterine standard experienced the primary outcome more than twice as often as those considered non-small for gestational age by both standards (18.4% vs 7.9%; P<.001). For the prediction of the primary outcome, small for gestational age by the intrauterine standard had higher sensitivity (29% vs 15%; P<.001) but lower specificity (87% vs 93%; P<.001) than by the birthweight standard. Both standards had weak performance overall, although the intrauterine standard had a higher area under the curve (0.58 vs 0.53; P<.001). When subanalyzed by gestational age at birth, the difference in areas under the curve was only present among preterm deliveries 34 to 36 competed weeks. Neither standard demonstrated any discrimination for morbidity prediction among term births (area under the curve, 0.50 for both). When the prediction of severe morbidity was compared, the intrauterine still had better overall prediction than the birthweight standard (areas under the curve, 0.65 vs 0.57; P<.001), although this also varied by gestational age at birth.

CONCLUSION

Among nonanomalous neonates, neither intrauterine nor birthweight-derived standards for small for gestational age accurately predicted neonatal morbidity and mortality, with no discriminatory ability at term. Small for gestational age intrauterine standards performed better than birthweight standards.

Miscarriage matters: the epidemiological, physical, psychological, and economic costs of early pregnancy loss

Miscarriage is generally defined as the loss of a pregnancy before viability. An estimated 23 million miscarriages occur every year worldwide, translating to 44 pregnancy losses each minute. The pooled risk of miscarriage is 15·3% (95% CI 12·5-18·7%) of all recognised pregnancies. The population prevalence of women who have had one miscarriage is 10·8% (10·3-11·4%), two miscarriages is 1·9% (1·8-2·1%), and three or more miscarriages is 0·7% (0·5-0·8%). Risk factors for miscarriage include very young or older female age (younger than 20 years and older than 35 years), older male age (older than 40 years), very low or very high body-mass index, Black ethnicity, previous miscarriages, smoking, alcohol, stress, working night shifts, air pollution, and exposure to pesticides. The consequences of miscarriage are both physical, such as bleeding or infection, and psychological. Psychological consequences include increases in the risk of anxiety, depression, post-traumatic stress disorder, and suicide. Miscarriage, and especially recurrent miscarriage, is also a sentinel risk marker for obstetric complications, including preterm birth, fetal growth restriction, placental abruption, and stillbirth in future pregnancies, and a predictor of longer-term health problems, such as cardiovascular disease and venous thromboembolism. The costs of miscarriage affect individuals, health-care systems, and society. The short-term national economic cost of miscarriage is estimated to be £471 million per year in the UK. As recurrent miscarriage is a sentinel marker for various obstetric risks in future pregnancies, women should receive care in preconception and obstetric clinics specialising in patients at high risk. As psychological morbidity is common after pregnancy loss, effective screening instruments and treatment options for mental health consequences of miscarriage need to be available. We recommend that miscarriage data are gathered and reported to facilitate comparison of rates among countries, to accelerate research, and to improve patient care and policy development.

New Australian birthweight centiles

OBJECTIVES

To prepare more accurate population-based Australian birthweight centile charts by using the most recent population data available and by excluding pre-term deliveries by obstetric intervention of small for gestational age babies.

DESIGN

Population-based retrospective observational study.

SETTING

Australian Institute of Health and Welfare National Perinatal Data Collection.

PARTICIPANTS

All singleton births in Australia of 23-42 completed weeks' gestation and with spontaneous onset of labour, 2004-2013. Births initiated by obstetric intervention were excluded to minimise the influence of decisions to deliver small for gestational age babies before term.

MAIN OUTCOME MEASURES

Birthweight centile curves, by gestational age and sex.

RESULTS

Gestational age, birthweight, sex, and labour onset data were available for 2 807 051 singleton live births; onset of labour was spontaneous for 1 582 137 births (56.4%). At pre-term gestational ages, the 10th centile was higher than the corresponding centile in previous Australian birthweight charts based upon all births.

CONCLUSION

Current birthweight centile charts probably underestimate the incidence of intra-uterine growth restriction because obstetric interventions for delivering pre-term small for gestational age babies depress the curves at earlier gestational ages. Our curves circumvent this problem by excluding intervention-initiated births; they also incorporate more recent population data. These updated centile curves could facilitate more accurate diagnosis of small for gestational age babies in Australia.

Identification of the optimal growth charts for use in a preterm population: An Australian state-wide retrospective cohort study

BACKGROUND

Preterm infants are a group at high risk of having experienced placental insufficiency. It is unclear which growth charts perform best in identifying infants at increased risk of stillbirth and other adverse perinatal outcomes. We compared 2 birthweight charts (population centiles and INTERGROWTH-21st birthweight centiles) and 3 fetal growth charts (INTERGROWTH-21st fetal growth charts, World Health Organization fetal growth charts, and Gestation Related Optimal Weight [GROW] customised growth charts) to identify which chart performed best in identifying infants at increased risk of adverse perinatal outcome in a preterm population.

METHODS AND FINDINGS

We conducted a retrospective cohort study of all preterm infants born at 24.0 to 36.9 weeks gestation in Victoria, Australia, from 2005 to 2015 (28,968 records available for analysis). All above growth charts were applied to the population. Proportions classified as <5th centile and <10th centile by each chart were compared, as were proportions of stillborn infants considered small for gestational age (SGA, <10th centile) by each chart. We then compared the relative performance of non-overlapping SGA cohorts by each chart to our low-risk reference population (infants born appropriate size for gestational age [>10th and <90th centile] by all intrauterine charts [AGAall]) for the following perinatal outcomes: stillbirth, perinatal mortality (stillbirth or neonatal death), Apgar <4 or <7 at 5 minutes, neonatal intensive care unit admissions, suspicion of poor fetal growth leading to expedited delivery, and cesarean section. All intrauterine charts classified a greater proportion of infants as <5th or <10th centile than birthweight charts. The magnitude of the difference between birthweight and fetal charts was greater at more preterm gestations. Of the fetal charts, GROW customised charts classified the greatest number of infants as SGA (22.3%) and the greatest number of stillborn infants as SGA (57%). INTERGROWTH classified almost no additional infants as SGA that were not already considered SGA on GROW or WHO charts; however, those infants classified as SGA by INTERGROWTH had the greatest risk of both stillbirth and total perinatal mortality. GROW customised charts classified a larger proportion of infants as SGA, and these infants were still at increased risk of mortality and adverse perinatal outcomes compared to the AGAall population. Consistent with similar studies in this field, our study was limited in comparing growth charts by the degree of overlap, with many infants classified as SGA by multiple charts. We attempted to overcome this by examining and comparing sub-populations classified as SGA by only 1 growth chart.

CONCLUSIONS

In this study, fetal charts classified greater proportions of preterm and stillborn infants as SGA, which more accurately reflected true fetal growth restriction. Of the intrauterine charts, INTERGROWTH classified the smallest number of preterm infants as SGA, although it identified a particularly high-risk cohort, and GROW customised charts classified the greatest number at increased risk of perinatal mortality.

Country-Specific vs. Common Birthweight-for-Gestational Age References to Identify Small for Gestational Age Infants Born at 24-28 weeks: An International Study

BACKGROUND

Controversy exists as to whether birthweight-for-gestational age references used to classify infants as small for gestational age (SGA) should be country specific or based on an international (common) standard. We examined whether different birthweight-for-gestational age references affected the association of SGA with adverse outcomes among very preterm neonates.

METHODS

Singleton infants (n = 23 788) of 24(0) -28(6) weeks' gestational age in nine high-resource countries were classified as SGA (<10th centile) using common and country-specific references based on birthweight and estimated fetal weight (EFW). For each reference, the adjusted relative risk (aRR) for the association of SGA with composite outcome of mortality or major morbidity was estimated.

RESULTS

The percentage of infants classified as SGA differed slightly for common compared with country specific for birthweight references [9.9% (95% CI 9.5, 10.2) vs. 11.1% (95% CI 10.7, 11.5)] and for EFW references [28.6% (95% CI 28.0, 29.2) vs. 24.6% (95% CI 24.1, 25.2)]. The association of SGA with the composite outcome was similar when using common or country-specific references for the total sample for birthweight [aRRs 1.47 (95% CI 1.43, 1.51) and 1.48 (95% CI 1.44, 1.53) respectively] and for EFW references [aRRs 1.35 (95% CI 1.31, 1.38) and 1.39 (95% CI 1.35, 1.43) respectively].

CONCLUSION

Small for gestational age is associated with higher mortality and morbidity in infants born <29 weeks' gestational age. Although common and country-specific birthweight/EFW references identified slightly different proportions of SGA infants, the risk of the composite outcome was comparable.

Defining small-for-gestational-age: prescriptive versus descriptive birthweight standards

Descriptive population-based birthweight standards possess low sensitivity in detecting infants with growth impairment. A prescriptive birthweight standard based on a 'healthy' subpopulation without risk factors for intrauterine growth restriction might be superior. We created two birthweight standards based on live born, singleton infants with gestational age 24-42 weeks and born in The Netherlands between 2000 and 2007. Inclusion criteria for the prescriptive birthweight standard were restricted to infants without congenital malformations, born to healthy mothers after uncomplicated pregnancies. We defined small-for-gestational-age (SGA) as birthweight <10th percentile and assessed the ability of both standards to predict adverse neonatal outcomes. The prescriptive birthweight standard identified significantly more infants as SGA, up to 38.0 % at 29 weeks gestation. SGA infants classified according to both standards as well as those classified according to the prescriptive birthweight standard only, were at increased risk of both major and minor adverse neonatal outcomes. The prescriptive birthweight standard was both more sensitive and less specific, with a maximum increase in sensitivity predicting bronchopulmonary dysplasia (+42.6 %) and a maximum decrease in specificity predicting intraventricular haemorrhage (-26.9 %) in infants aged 28-31 weeks.

CONCLUSION

Prescriptive birthweight standards could improve identification of infants born SGA and at risk of adverse neonatal outcomes.

WHAT IS KNOWN

• Descriptive birthweight standards possess low sensitivity in detecting growth restricted infants at risk of adverse neonatal outcomes. • Prescriptive standards could improve identification of very preterm small-for-gestational-age (SGA) infants at risk of intraventricular haemorrhage. What is New: • Prescriptive standards identify more preterm and term SGA infants at risk of major adverse neonatal outcomes. • Late preterm and term SGA infants classified according to the prescriptive standard are at increased risk of minor adverse neonatal outcomes with potentially harmful implications.

Mortality and morbidity risks vary with birth weight standard deviation score in growth restricted extremely preterm infants

OBJECTIVE

To assess whether the mortality and morbidity risks vary with birth weight standard deviation score (BWSDS) in growth restricted extremely preterm infants.

STUDY DESIGN

This was a multicenter retrospective cohort study using the database of the Neonatal Research Network of Japan and including 9149 infants born between 2003 and 2010 at <28 weeks gestation. According to the BWSDSs, the infants were classified as: <-2.0, -2.0 to -1.5, -1.5 to -1.0, -1.0 to -0.5, and ≥-0.5. Infants with BWSDS≥-0.5 were defined as non-growth restricted group.

RESULTS

After adjusting for covariates, the risks of mortality and some morbidities were different among the BWSDS groups. Compared with non-growth restricted group, the adjusted odds ratio (aOR) for mortality [aOR, 1.69; 95% confidence interval (CI), 1.35-2.12] and chronic lung disease (CLD) (aOR, 1.28; 95% CI, 1.07-1.54) were higher among the infants with BWSDS -1.5 to <-1.0. The aOR for severe retinopathy of prematurity (ROP) (aOR, 1.36; 95% CI, 1.09-1.71) and sepsis (aOR, 1.72; 95% CI, 1.32-2.24) were higher among the infants with BWSDS -2.0 to <-1.5. The aOR for necrotizing enterocolitis (NEC) (aOR, 2.41; 95% CI, 1.64-3.55) was increased at a BWSDS<-2.0.

CONCLUSION

Being growth restricted extremely preterm infants confer additional risks for mortality and morbidities such as CLD, ROP, sepsis and NEC, and these risks may vary with BWSDS.

New Japanese neonatal anthropometric charts for gestational age at birth

BACKGROUND

More than 10 years have passed since the previous Japanese neonatal growth charts were published, therefore the aim of this study was to develop an updated set of Japanese neonatal growth charts.

METHODS

We used data from the registry database of the Japan Society of Obstetrics and Gynecology from 2003 until 2005. A total of 150,471 singleton live births without stillbirth or severe congenital malformation were enrolled in the preliminary analysis. It was found that the distribution of the 10th centile charts based on these subjects was skewed toward lower birthweight for preterm infants, because of the significantly lower birthweight in the 10th centile in neonates delivered by cesarean section than those delivered vaginally. Therefore, the data of subjects delivered by cesarean section were also excluded.

RESULTS

Finally, 104,748 singleton vaginal births at 22-41 weeks of gestation were used to construct a new set of Japanese neonatal anthropometric charts. The birthweight chart is parity and sex specific. The differences between the Japanese fetal growth chart and the new neonatal birthweight chart were small.

CONCLUSION

The present new neonatal anthropometric charts may reveal unrestricted growth pattern mimicking fetal growth. Use of these charts may result in recognition of abnormal fetal growth and risk in preterm infants. Further studies are needed to evaluate the risk for adverse neonatal and long-term outcome among small-for-gestational-age infants using these neonatal charts.

Racial disparities in stillbirth risk across gestation in the United States

OBJECTIVE

We sought to determine factors associated with racial disparities in stillbirth risk.

STUDY DESIGN

Stillbirth hazard was analyzed using 5,138,122 singleton gestations from the National Center of Health Statistics perinatal mortality and birth files, 2001-2002.

RESULTS

Black women have a 2.2-fold increased risk of stillbirth compared with white women. The black/white disparity in stillbirth hazard at 20-23 weeks is 2.75, decreasing to 1.57 at 39-40 weeks. Higher education reduced the hazard for whites more than for blacks and Hispanics. Medical, pregnancy, and labor complications accounted for 30% of the hazard in blacks and 20% in whites and Hispanics. Congenital anomalies and small for gestational age contributed more to preterm stillbirth risk among whites than blacks. Pregnancy and labor conditions contributed more to preterm stillbirth risk among blacks than whites.

CONCLUSION

The excess stillbirth risk for blacks was greatest at preterm gestations, and factors contributing to stillbirth risk vary by race and gestational age.

Nutritional support of very low birth weight newborns

Nutritional support to promote optimal postnatal growth for very low birth weight (VLBW) newborns less than 1500 g at birth during the initial prolonged hospitalization is a significant issue. This article reviews the concepts involved in the nutritional support of VLBW newborns, including definitions and discussions of growth, optimal postnatal growth, body composition, initial weight loss, growth expectations, growth assessment tools used during the postnatal period, the relation between inadequate nutrition and neurodevelopment, the relation between protein intake and cognitive outcome, postnatal nutrition balance, the potential for programming of future adult-onset chronic conditions, a review of fetal nutritional intake, and current recommendations for nutritional support of VLBW newborns.

Fundamental frequency of neonatal crying: does body size matter?

The objective of this study was to determine the influence of fetal growth on the fundamental frequency (F(0)) of neonatal crying in a group of healthy full-term infants. The spontaneous cries of 131 infants were audio recorded during the first week of life, and subsequently submitted to acoustic analyses. The individual cry utterances produced by each infant were measured for minimum, mean, and maximum F(0). The infants were placed into one of three groupings (low, average, high) based on body size indices according to the ponderal index (PI), the ratio of body weight to body length (BW/L), and body weight (BW) alone. The F(0) features of infants in each subgrouping of body size were compared and contrasted. The results indicated that features of cry F(0) were found to decrease marginally as a function of increased body size, with significant group differences confined to maximum F(0). The BW index appeared to be the most sensitive measure in differentiating infant groups according to body size. In general, neonatal body size appears to have a slight, although nonsignificant influence on the vocal F(0) of crying in healthy full-term infants. Any body size-related changes in cry F(0) are likely to be found for maximum F(0) and may reflect stress-related variations in nervous system activation.