The use of customised versus population-based birthweight standards in predicting perinatal mortality

OBJECTIVE: The objective of this study was to critically examine potential artifacts and biases underlying the use of 'customised' standards of birthweight for gestational age (GA). DESIGN: Population-based cohort study. SETTING: Sweden. POPULATION: A total of 782,303 singletons > or =28 weeks of gestation born in 1992-2001 to Nordic mothers with complete data on birthweight; GA; and maternal age, parity, height, and pre-pregnancy weight. METHODS: We compared perinatal mortality in four groups of infants based on the following classification of small for gestational age (SGA): non-SGA based on either population-based or customised standards (the reference group), SGA based on the population-based standard only, SGA based on the customised standard only, and SGA according to both standards. We used graphical methods to compare GA-specific birthweight cutoffs for SGA using the two standards and also used logistic regression to control for differences in GA and maternal pre-pregnancy body mass index (BMI) in the four groups. MAIN OUTCOME MEASURES: Perinatal mortality, including stillbirth and neonatal death. RESULTS: Customisation led to a large artifactual increase in the proportion of SGA infants born preterm. Adjustment for differences in GA and maternal BMI markedly reduced the excess risk among infants classified as SGA by customised standards only. CONCLUSION: The large increase in perinatal mortality risk among infants classified as SGA based on customised standards is largely an artifact due to inclusion of more preterm births.     

Application of a customised birthweight standard in the assessment of perinatal outcome in a high risk population

Objective Physiological as well as pathological variables influence birthweight. The aim of the present study was to examine perinatal outcome in relation to birthweight centiles applying a customised birthweight standard.
Methods Two hundred and seventeen babies from high risk pregnancies were evaluated and classified as small or not small for gestational age according to two standards: 1. conventional Dutch birthweight centiles and 2. customised centiles which adjust individually for physiological variables like maternal booking weight, height and ethnic origin.
Results Customisation of the weight standards resulted in identification of an additional group of infants who were small for gestational age, but not by the Dutch standards. These babies were associated with significantly more adverse perinatal events than those who were not small for gestational age as defined by a customised standard.
Conclusions Adjustment of birthweight centiles for physiological variables significantly improves the identification of infants who have failed to reach the expected birthweight and who are at increased risk for adverse perinatal events.     

The relation of breech presentation at term tocerebral palsy

Objective To examine the relation between breech delivery and cerebral palsy, considering the influence of intrauterine growth, low Apgar score at birth, and mode of delivery.
Design Register-based, case-control study.
Population A cohort of infants with cerebral palsy born between 1979 and 1986 in east Denmark, identified by linkage of the cerebral palsy register with the national birth register. Discharge letters from births of breech infants with cerebral palsy were reviewed.
Main outcome measures Presentation, mode of delivery, gestational age, birthweight, Apgar score, type of cerebral palsy, severity of handicap.
Results Breech presentation at term was associated with a borderline significantly higher risk of cerebral palsy than vertex presentation (OR 1.56; 95% CI 0.9–2.4). Breech presentation infants more often had a lower Apgar score (< 7 at 5 minutes) and were smaller for gestational age (SGA < 2 SD) than were those with vertex presentation; infants with a low Apgar score, or who were small for gestational age, had a higher risk of cerebral palsy. After stratification by being small for gestational age the risk of cerebral palsy was not related to presentation. There were no differences between breech and vertex infants with cerebral palsy in terms of low Apgar score, being small for gestational age, mode of delivery, and severity of the handicap. Breech presentation infants were more often classified as diplegic (77.8% versus 42.3% in cephalic infants).
Conclusion The risk of cerebral palsy among term breech presentation infants does not seem to be related to mode of delivery, but is more likely linked to a higher rate of being small for gestational age in breech infants.     

Significance of low birthweight for gestational age among very preterm infants

Objective To estimate the risk of specific adverse neonatal events resulting from the combined effects of prematurity and low birthweight in very preterm infants (delivered at 24–31 weeks of gestation)
Design A cohort study of specific adverse neonatal events in preterm infants born at between 24 and 31 weeks of gestation.
Setting Pavia, Italy.
Population Two hundred and thirty singleton infants with sonographically confirmed gestational age, delivered at 24 to 31 weeks of gestation.
Methods To evaluate the impact of a lower than expected birthweight on selected neonatal events independently of gestational age, we calculated birthweight standard deviation scores (differences between actual birthweight and fitted birthweight divided by fitted standard deviation) for each week of gestation.
Results After adjustment for gestational age and other confounders, there was a significant linear trend relating a decreasing birthweight SDS to an increased likelihood of neonatal death, intraventricular haemorrhage, severe respiratory distress syndrome, and acidosis. Compared with infants with SDS 0 ( 50th centile of birthweight), infants with birthweight SDS < −1 (< 16th centile) had increased odds for neonatal death [odds ratio (OR) 3.7, 95% confidence interval (CI) 1.42–9.6], grade III-IV intraventricular haemorrhage (OR 17.5, 95% CI 4.04–75.9), and neonatal acidosis (OR 3.22, 95% CI 1.41–7.4). The significance of birthweight SDS as a predictor of neonatal outcome, however, was lower than that of gestational age.
Conclusions A lower than expected birthweight affects the likelihood of several adverse neonatal events in very preterm infants. However, a decreasing birthweight SDS affects neonatal outcome less than decreasing gestation does.     

Relationship between customised birthweight centiles and neonatal anthropometric features of growth restriction

Objective To determine the relationship between customised birthweight centiles (adjusted for maternal and fetal physiological variables) and neonatal anthropometric features of intrauterine growth restriction (IUGR).
Design Observational study.
Population Two-hundred and seventy women with low risk pregnancies participating in a cohort study of serial ultrasound biometry.
Methods Customised birthweight centiles were calculated following adjustment for maternal weight, height and ethnic origin, gestational age at delivery, birth order, and sex of the infant. Three separate neonatal anthropometric measures were used to define IUGR: subscapular or triceps skinfold thickness  <10th  centile; ponderal index  <25th  centile; and mid-arm circumference to occipito-frontal circumference ratio (MAC/OFC) <−1 standard deviation (SD). Relationship of the centiles to these outcomes was evaluated using likelihood ratios (LR) and kappa statistic. These approaches allowed us to examine the strength of the association: an LR of 5–10 would be expected to generate moderate changes in the pre-test probability of IUGR, whereas a kappa value of 0.2–0.4 would reflect fair agreement between customised birthweight centiles and neonatal anthropometric measures.
Results Customised birthweight centile of 10 or less had the following LR values for the various anthropometric criteria for IUGR: 5.1 (95% CI 3–8.5) for low skinfold thickness; 4.3 (95% CI 2.5–7.1) for low ponderal index; and 3.9 (95% CI 2–6.6) for low MAC/OFC ratio. The kappa values were: 0.4 (95% CI 0.26–0.51) for low skinfold thickness; 0.33 (95% CI 0.21–0.46) for low ponderal index; and 0.13 (95% CI 0–0.26) for low MAC/OFC ratio.
Conclusion In a low risk population, customised birthweight centiles can only be moderately useful in the identification of neonates with low skinfold thickness and low ponderal index.     

Predictiveness of antenatal umbilical artery Doppler for adverse pregnancy outcome in small-for-gestational-age babies according to customised birthweight centiles: population-based study

Objective  To examine the relationship between smallness at birth and the predictive value of umbilical artery Doppler.
Design  Retrospective cohort.
Setting  Tertiary referral university hospital, Barcelona.
Population  A total of 7645 singleton pregnancies delivered between January 2002 and June 2004.
Methods  The associations with adverse outcome were assessed for small-for-gestational-age (SGA) babies according to customised standards who had normal and abnormal umbilical artery Doppler.
Main outcome measures  Neonatal morbidity and perinatal mortality.
Results  Of the 369 SGA fetuses that had been identified antenatally, 70 (19%) had an abnormal umbilical artery Doppler and the babies from these pregnancies had a higher risk for neonatal morbidity when compared with babies with normal birthweight (OR 3.99, 95% CI 1.04–11.03). However, the remaining 299 (81%) fetuses with normal umbilical artery Doppler also had an elevated risk of neonatal morbidity (OR 2.26, 95% CI 1.04–4.39). Overall, many of the instances of adverse outcome associated with smallness for gestational age were attributable to the group with normal Doppler than to the group with abnormal Doppler.
Conclusion  Normal antenatal umbilical artery Doppler cannot be taken as an indicator of low risk in pregnancies where the fetus is SGA according to customised percentiles.     

Development of a customised birthweight standard for ethnic Chinese subjects

A model to establish customised birthweight standards for the Chinese population was developed, using data from a cohort of 1564 Chinese women with normal singleton pregnancies. Multiple regression analysis was performed using maternal height, weight, parity, gestation at delivery and fetal sex as independent (predictor) variables. From this, a customised ideal birthweight for each baby can be estimated, and the normality of the actual birthweight can be evaluated according to this, rather than from population standards. The results of this study show that birthweights are strongly influenced by maternal characteristics, confirming conclusions from similar studies in other ethnic populations. The overall mean birthweight at 280 days of gestation was 3252 g, which was smaller than that of the Caucasian population. Birthweight increased with maternal height (5.1 g/cm), maternal booking weight (10.2 g/kg) and gestation at delivery (18.3 g/day from 280 days). Babies from women who had two previous deliveries weighed 145.2 g more than the nulliparous. Male babies were 84.8 g heavier than females. Adjustment using these results produces a customised ideal birthweight for each baby. When compared with population based standards, customised birthweight standards identified significantly fewer small for gestational age (SGA - birthweight below 10th centile, McNemar Chi square = 19.1, p < 0.01) and fewer large for gestational age (LGA - birthweight above 90th centile, McNemar Chi square = 23.7, p < 0.01) cases.     

Preterm and term births of small for gestational age infants: a population-based study of risk factors among nulliparous women

Objective To study risk factors for small for gestational age (SGA) infants by gestational age among nulliparous women and to estimate mortality rates among SGA and appropriate-for-gestational-age (AGA) infants by gestational age.
Design A population-based study from the Swedish Medical Birth Register.
Setting Sweden 1992–1993.
Population Liveborn singleton infants to nulliparous women (   n = 96,662  ).
Main outcome measures Crude and adjusted odds ratios of risk factors for SGA by gestational age. Rates of neonatal and postneonatal mortality.
Results Older maternal age (≥ 30 years) was foremost associated with increased risks of very and moderately preterm SGA (≥ 32 weeks and 33–36 weeks, respectively), but also with term SGA (≥ 37 weeks). Risks of SGA increased with decreasing maternal height at all gestational ages. Smoking increased the risks of moderately preterm and term SGA. Short maternal education increased the risk of preterm SGA and low pre-pregnancy body mass index slightly increased the risk of term SGA. Pre-eclampsia and essential hypertension foremost increased the risk of very preterm SGA (OR = 40.5 and 32.4, respectively) and moderately preterm SGA (OR = 17.4 and 10.6, respectively), but also increased the risk of term SGA. Neonatal and postneonatal mortality rates of SGA infants were substantially influenced by gestational age, and mortality rates were consistently higher among preterm SGA infants compared with AGA infants.
Conclusions Risk factors for SGA and mortality rates among SGA infants vary by gestational age. A subdivision of risk factors by gestational age adds knowledge, particularly about risks of preterm SGA, where the highest rates of mortality were observed.     

Neonatal mortality amongst Scottish preterm singleton births (1985–1994)

Objective To provide a valid estimate of singleton neonatal mortality based on birthweight and gestational age at delivery.
Design Record linkage of maternity data and neonatal mortality data.
Setting Scotland, UK.
Population All singleton preterm deliveries from 24 to 36 weeks inclusive between 1985 and 1994.
Main outcome measure Neonatal death.
Results There were 625,646 liveborn singleton deliveries over the study period, of which 33,912 were preterm (5.4%). The overall neonatal mortality in the preterm group was 41/1000 and the data have been presented by both gestational age and birthweight. The neonatal mortality rate fell with advancing gestation from 795/1000 live births at 24 weeks to 9/1000 live births at 36 weeks and was higher at the extremes of birthweight for a given gestational age. There was a significant increase in the proportion of babies delivered iatrogenically over the study period (χ test for trend   P < 0.001  ).
Conclusion This is the largest recent series to consider neonatal mortality using both birthweight and gestational age. These figures will be of use in obstetric management when elective preterm delivery is considered, and for providing prognostic guidance following preterm delivery.     

The value of customised centiles in assessing perinatal mortality risk associated with parity and maternal size

Objective  We wanted to compare customised and population standards for defining smallness for gestational age (SGA) in the assessment of perinatal mortality risk associated with parity and maternal size.
Design  Population-based cohort study.
Setting  Sweden.
Population  Swedish Birth Registry database 1992–1995 with 354 205 complete records.
Method  Coefficients were derived and applied to determine SGA by the fully customised method, or by adjustment for fetal sex only, and using the same fetal weight standard.
Main outcome measure  Perinatal deaths and rates of small for gestational age (SGA) babies within subgroups stratified by parity, body mass index (BMI) and maternal size within the BMI range of 20.0–24.9.
Results  Perinatal mortality rates (PMR) had a U-shaped distribution in parity groups, increased proportionately with maternal BMI, and had no association with maternal size within the normal BMI range. For each of these subgroups, SGA rates determined by the customised method showed strong association with the PMR. In contrast, SGA based on uncustomised, population-based centiles had poor correlation with perinatal mortality. The increased perinatal mortality risk in pregnancies of obese mothers was associated with an increased risk of SGA using customised centiles, and a decreased risk of SGA using population-based centiles.
Conclusion  The use of customised centiles to determine SGA improves the identification of pregnancies which are at increased risk of perinatal death.     

Neighbourhood Family Income and Adverse Birth Outcomes Among Singleton Deliveries

ObjectiveTo assess the association between neighbourhood family income and adverse birth outcomes.MethodsWe conducted a retrospective cohort study of 334 231 singleton births during 2004 and 2006 based on the Niday Perinatal Database from Ontario. Median neighbourhood family incomes from the 2001 Canadian census were linked with the Niday Perinatal Database by dissemination areas. Generalized estimating equations were applied to estimate the odds ratios of adverse birth outcomes associated with lower neighbourhood income, with adjustment for maternal confounding variables at the individual level.ResultsCompared with the highest neighbourhood income quintile, mothers from the lowest quintile were at increased risk of having small for gestational age neonates (OR 1.51; 95% CI 1.46 to 1.57), low birth weight (OR 1.43; 95% CI 1.36 to 1.50), preterm birth (OR 1.17; 95% CI 1.12 to 1.23), low Apgar score (< 7) at five minutes (OR 1.32; 95% CI 1.21 to 1.44), and stillbirth (OR 1.39; 95% CI 1.19 to 1.62). The risks of women from the lowest income quintiles delivering a macrosomic baby (OR 0.81; 95% CI 0.79 to 0.84) or a large for gestational age baby (OR 0.82; 95% CI 0.80 to 0.85) were significantly decreased. No difference in risk of congenital anomaly was found among different income quintiles.ConclusionA lower level of neighbourhood income is associated with increased risks of small for gestational age babies, low birth weight, preterm birth, low Apgar score at five minutes, and stillbirth.     

The utility of an obesity-specific small for gestational age standard for pregnancies complicated by maternal obesity*

Introduction: An obesity-specific standard for small for gestational age (SGA) pregnancies may help identify additional at risk pregnancies.

Methods: This was a retrospective cohort study of all non-anomalous singleton neonates born in Texas from 2006–2011. Analysis was limited to births between 34 and 42?weeks gestation. Two SGA birth weight standards (birth weight ≤10th centile) were generated, one using the entire population (SGA_pop) and another using obese pregnancies (SGA_cust). The outcomes of interest included: risks of stillbirth, neonatal death, 5-minute Apgar score below 7, NICU admission, and assisted ventilation?>6?h.

Results: Using the population standard, the prevalence of SGA complicated by obesity was 8.1%, compared with 10.3% using the obesity-specific standard. 10,457 additional pregnancies were identified as SGA. Compared to obese AGA pregnancies, the aHR for stillbirth was 5.45 [4.28, 6.94] for SGA_pop, and 1.21 [0.54, 2.74] for SGA_cust-pop. The risks for the following neonatal complications were slightly higher for SGA_cust-pop group compared to AGA group: neonatal death aOR 1.40 [1.05, 1.87], low 5-minute Apgar 1.31 [1.09, 1.57], and NICU admission 1.13 [1.03, 1.25]. These risks were lower than SGA_pop.

Conclusions: Using an obesity-specific SGA standard, a subgroup of pregnancies with marginally increased risk for neonatal complications was identified.     

Is obstetric and neonatal outcome worse in fetuses who fail to reach their own growth potential?

OBJECTIVES: To determine the perinatal outcome of fetuses who had birthweights less than that expected from early third trimester ultrasound scanning. DESIGN: Retrospective estimation of centile fetal weight at early third trimester ultrasound scanning compared with actual centile birthweight corrected for gestational age, parity and sex. SETTING: Teaching Hospital Obstetric Unit, London. SUBJECTS: 197 unselected women with singleton cephalic pregnancies who were delivered at term in our unit between October 1989 and May 1990. MAIN OUTCOME MEASURES: CTG abnormality, need for fetal blood sampling in labour, meconium-staining of the amniotic fluid, mode of delivery, Apgar scores at 1 and 5 min, need for transfer of baby to neonatal unit, and need for neonatal intubation of the neonate at delivery. RESULTS: An actual birthweight greater than 5% less than the birthweight estimated from ultrasound scanning identified 44 babies (22%) with an increased risk of CTG abnormalities (chi 2 = 8.38, P less than 0.0025; Odds ratio (OR) = 2.54; 95% CI 1.36 to 4.78) and need for operative delivery (chi 2 = 5.81, P less than 0.0125; OR = 1.94; 95% CI 1.15 to 3.27), when compared with the remainder of the sample. Overall 14 (32%) of this group had birthweights above the 50th centile. A group of 44 babies selected as being the smallest for gestational age, without reference to growth pattern, had a similar excess morbidity. (All this group had birthweights below the 39th centile). CONCLUSIONS: This study supports the hypothesis that in-utero fetal growth pattern is as important for perinatal outcome as being small for gestational age per se.     

Genetic influence on birthweight and gestational length determined by studies in offspring of twins

Objective To determine the relative importance of genetic effects on birthweight, gestational length and small for gestational age.
Design A cohort study, using individual record linkage between the population-based Swedish Twin and Birth Registers to estimate twin similarities in twins with known zygosity.
Population Included were 868 monozygotic and 1141 dizygotic female twin pairs, born in Sweden before 1959, who both delivered single births from 1973–1993.
Methods Quantitative genetic methods, offspring birthweight, gestational length and small for gestational age birth in twin sisters.
Main outcome measures Twin similarities measured as probandwise concordance rates and intra-class correlations for birthweight, gestational length and small for gestational age births.
Results Concordance rates and intra-class correlations for birthweight, gestational length and small for gestational age were consistently higher in monozygotic compared with dizygotic twins. Model fitting suggested heritability estimates in the range from 25% to 40%.
Conclusions This study suggests genetic effects not only for birthweight and fetal growth, but also for gestational length. The mediation of these genetic effects may partly be due to similarities in maternal antropometric measures, lifestyle and medical complications during pregnancy. The study does not distinguish between fetal and maternal genetic effects.     

Perinatal outcome of pregnancies complicated with extreme birth weights at term

Objective: The objective of this study is to investigate whether an abnormal birthweight at term, either small for gestational age (SGA,??95th centile for gestational age), is a risk factor for perinatal complications as compared with birthweight appropriate for gestational age (AGA).

Methods: A population-based retrospective cohort analysis of all singleton pregnancies delivered between 1991 and 2014 at Soroka Medical Center. Congenital malformations and multiple pregnancies were excluded. A multivariable generalized estimating equation regression model was used to control for maternal clusters and other confounders.

Results: During the study period, 228,242 births met the inclusion criteria, of them 91% were AGA (n?=?207,652), 4.7% SGA, and 4.3% LGA. SGA significantly increased the risk for perinatal mortality (aOR 5.6, 95%CI 4.5–6.8) and low 5-min Apgar scores (aOR 2.2, 95%CI 2.0–2.4), while LGA did not. SGA and LGA were both significant risk factors for cesarean delivery. LGA was significantly associated with shoulder dystocia and post-partum hemorrhage (aOR =13.6, 95%CI 10.9–17.0, and aOR 1.7, 95%CI 1.2–2.6, respectively).

Conclusions: Extreme birthweights at term are significantly associated with adverse maternal and neonatal outcomes. As opposed to SGA, LGA is not independently associated with perinatal mortality.     

The influence of interpregnancy interval on the subsequent risk of stillbirth and early neonatal death

OBJECTIVE: To study whether interpregnancy interval is associated with increased risks of stillbirth and early neonatal death and whether this possible association is confounded by maternal characteristics and previous reproductive history. METHODS: In a Swedish nationwide study of 410,021 women's first and second singleton deliveries between 1983 and 1997, we investigated the influence of interpregnancy interval on the subsequent risks of stillbirth and early neonatal death. Odds ratios (ORs) with 95% confidence intervals (CIs) estimated using unconditional logistic regression were adjusted for maternal characteristics and previous pregnancy outcome categorized into stillbirth, early neonatal death, preterm, or small for gestational age delivery. RESULTS: Compared with interpregnancy intervals between 12 and 35 months, very short interpregnancy intervals (0-3 months) were, in the univariate analyses, associated with increased risks of stillbirth and early neonatal death (crude OR 1.9; 95% CI 1.3, 2.7; and 1.8; 1.2, 2.8, respectively). However, after adjusting for maternal characteristics and previous reproductive history, women with interpregnancy intervals of 0 to 3 months were not at increased risks of stillbirth (adjusted OR 1.3; 95% CI 0.8, 2.1) or early neonatal death (adjusted OR 0.9; 95% CI 0.5, 1.6). Women with interpregnancy intervals of 72 months and longer were at increased risk of stillbirth (adjusted OR 1.5; 95% CI 1.1, 2.1) and possibly early neonatal death (adjusted OR 1.3; 95% CI 0.9, 2.1). CONCLUSION: Short interpregnancy intervals appear not to be causally associated with increased risk of stillbirth and early neonatal death, whereas long interpregnancy intervals were associated with increased risk of stillbirth and possibly early neonatal death.     

Birthweight percentiles by gestational age in multiple births. A population-based study of Norwegian twins and triplets

OBJECTIVE: To assess secular trends for birthweight by gestational age in twins in Norway and to develop current national birthweight standards by gestational age for twin and triplet births using population-based data. MATERIAL AND METHODS: The analysis of secular trends for birthweight and gestational age in twins was based on 32,379 twin livebirths (1967-95). Taking into account the observed secular trends in birthweight for 35-40 weeks of gestation, data on twins born during 1987-95 only were included in the calculation of birthweight percentiles for 35-40 weeks, while for lower and upper weeks, data on twins born during 1967-95 were used. The construction of birthweight-for-gestation curves for triplets was based on the data on 690 triplets. RESULTS: Whereas the overall mean birthweight and gestational age decreased in 1987-95 compared with the previous years, the mean birthweights by gestational age for the 35-40 weeks of gestation was significantly higher in 1987-95. Male twins weighed more than female twins throughout the gestation with consistent and significant differences from 27 to 42 weeks of gestation. Smoothed curves for birthweight-by-gestational-age percentiles of male and female twins are plotted. The birthweight-by-gestational-age curves of triplets were almost identical with twin curves before 30 weeks of gestation, starting to diverge from them progressively thereafter. The intrauterine growth of twin births also starts to differ markedly from singletons at approximately 30 weeks of gestation. CONCLUSION: This study shows that plurality-specific birthweight-by-gestation standards should be used for assessment of fetal growth in multiple births rather than singleton standards.     

Stillbirths and neonatal deaths in appropriate, small and large birthweight for gestational age fetuses

AIMS: To compare the risk of stillbirth and neonatal death in small-for-gestational-age (SGA), appropriate-for-gestational-age (AGA) and large-for-gestational-age (LGA) fetuses and neonates. DESIGN: Retrospective analysis of 662 043 births and outcomes recorded in the Victorian Perinatal Data Collection Unit (1992-2002). INCLUSION CRITERIA: Births in Victoria in 1992-2002. EXCLUSION CRITERIA: Multiple pregnancy and congenital birth defects. MAIN OUTCOME MEASURES: Births, stillbirths and neonatal deaths at each week of gestation after 23 weeks were stratified by birthweight into appropriate, small and large for gestational age. Stillbirth risk per 1000 ongoing pregnancies and neonatal death rate per 1000 live births were calculated. RESULTS: For the AGA group, the overall stillbirth risk was 2.88 per 1000 and neonatal death rate was 1.35 per 1000. In the LGA group, these were 2.62 and 1.83 per 1000, respectively. The slight increase in neonatal death rate among LGA fetuses was confined to those delivered after 28 weeks gestation. In the SGA group, the stillbirth risk and neonatal death rate were 15.1 and 3.99 per 1000, respectively. CONCLUSION: The risk of stillbirth per week of gestational age and neonatal death rates do not differ significantly between AGA and LGA fetuses and neonates. The SGA fetus is at significantly greater risk of both stillbirth and neonatal death, particularly with advancing gestational age.     

Adverse perinatal outcomes among interracial couples in the United States

OBJECTIVE: We examined the association between parental race and stillbirth and adverse perinatal and infant outcomes. METHODS: We conducted a retrospective cohort analysis using the 1995-2001 linked birth and infant death files that are composed of live births and fetal and infant deaths in the United States. The study included singleton births delivered at 20 or more weeks of gestation with a fetus weighing 500 g or more (N = 21,005,786). Parental race was categorized as mother white-father white, mother white-father black, mother black-father white, and mother black-father black. Multivariable logistic regression analysis was performed to examine the association between parental race and risks of stillbirth (at > or = 20 weeks), small for gestational age (defined as birth weight < 5th and < 10th percentile for gestational age), and early neonatal (< 7 days), late neonatal (7-27 days), and postneonatal (28-364 days) mortality. All analyses were adjusted for the confounding effects of maternal age, education, trimester at which prenatal care began, parity, marital status, and smoking during pregnancy. RESULTS: Although risks varied across parental race categories, stillbirth was associated with a higher-than-expected risk for interracial couples: mother white-father black, relative risk (RR) 1.17 (95% confidence interval [CI] 1.10-1.26) and mother black-father white, RR 1.37 (95% CI 1.21-1.54) compared with mother white-father white parents. The RR for stillbirth was even higher among mother black-father black parents (RR 1.67, 95% CI 1.62-1.72). The overall patterns of association for small for gestational age births (< 5th and < 10th percentile) and early neonatal mortality were similar to those seen for stillbirth. CONCLUSION: There is an increased risk of adverse perinatal outcomes for interracial couples, including stillbirth, small for gestational age infants, and neonatal mortality. LEVEL OF EVIDENCE: II-2.     

The relation of breech presentation at term to cerebral palsy.

OBJECTIVE: To examine the relation between breech delivery and cerebral palsy, considering the influence of intrauterine growth, low Apgar score at birth, and mode of delivery. DESIGN: Register-based, case-control study. POPULATION: A cohort of infants with cerebral palsy born between 1979 and 1986 in East Denmark, identified by linkage of the cerebral palsy register with the national birth register. Discharge letters from births of breech infants with cerebral palsy were reviewed. MAIN OUTCOME MEASURES: Presentation, mode of delivery, gestational age, birthweight, Apgar score, type of cerebral palsy, severity of handicap. RESULTS: Breech presentation at term was associated with a borderline significantly higher risk of cerebral palsy than vertex presentation (OR 1.56; 95% CI 0.9-2.4). Breech presentation infants more often had a lower Apgar score (< 7 at 5 minutes) and were smaller for gestational age (SGA < 2 SD) than were those with vertex presentation; infants with a low Apgar score, or who were small for gestational age, had a higher risk of cerebral palsy. After stratification by being small for gestational age the risk of cerebral palsy was not related to presentation. There were no differences between breech and vertex infants with cerebral palsy in terms of low Apgar score, being small for gestational age, mode of delivery, and severity of the handicap. Breech presentation infants were more often classified as diplegic (77.8% versus 42.3% in cephalic infants). CONCLUSION: The risk of cerebral palsy among term breech presentation infants does not seem to be related to mode of delivery, but is more likely linked to a higher rate of being small for gestational age in breech infants.