Pregnancy-induced hypertension is associated with lower infant mortality in preterm singletons

OBJECTIVE: To assess the association between pregnancy-induced hypertension (PIH) and infant mortality. DESIGN: Retrospective cohort study. SETTING: Birth and infant death registration dataset of the USA. POPULATION: A total of 17,432,987 eligible, liveborn singleton births in 1995-2000. METHODS: Multivariate logistic regression was applied to evaluate the association between PIH and infant mortality, with adjustment of potential confounders. MAIN OUTCOME MEASURES: Infant death (0-364 days) and its three components: early neonatal death (0-6 days), late neonatal death (7-27 days), and postneonatal death (28-364 days). RESULTS: There was a significant reduction in infant mortality associated with PIH in early preterm infants (OR = 0.59, 95% CI: 0.56-0.63) and in late preterm infants (OR = 0.80, 95% CI: 0.73-0.87), but a significant increase in term infants (OR = 1.08, 95% CI: 1.02-1.14). Both in early preterm and late preterm births, early neonatal mortality (OR = 0.38, 95% CI: 0.34-0.42; OR = 0.68, 95% CI: 0.61-0.77) and late neonatal mortality (OR = 0.59, 95% CI: 0.50-0.70; OR = 0.76, 95% CI: 0.61-0.96) were decreased in infants born to mothers with PIH compared with those born to mothers with normal blood pressure. The PIH-associated reduction in neonatal mortality among preterm singletons was stronger in small-for-gestational-age infants than in normal growth infants and stronger in infants born to nulliparous women than in those born to multiparous women. CONCLUSIONS: PIH is associated with lower risk of infant death in preterm births but higher risk in term births.     

AGA-primed uteri compared with SGA-primed uteri and the success of subsequent in utero fetal programming

OBJECTIVE: To assess whether risk for early mortality is increased with recurrent small for gestational age (SGA) compared with nonrecurrent SGA. METHODS: We used the Missouri maternally linked cohort data containing births from 1978-1997. We identified mothers according to four categories: 1) appropriate for gestational age (AGA)-AGA: both first and second pregnancies were AGA; 2) AGA-SGA: first pregnancy was AGA, second pregnancy outcome changed to SGA (a switch); 3) SGA-AGA: first pregnancy was SGA, second pregnancy outcome AGA (a switch); 4) SGA-SGA: both first and second pregnancies were SGA. We then compared the success of fetal programming in the second pregnancy with a switch compared with a pregnancy without a switch (AGA-SGA compared with SGA-SGA; and SGA-AGA compared with AGA-AGA). We used neonatal mortality as primary outcome with infant and postneonatal mortality as secondary outcomes. RESULTS: Appropriate for gestational age infants from a SGA-primed uterus (SGA-AGA switch) had a 19% (odds ratio 1.19; 95% confidence interval 1.11-1.28) and 29% (odds ratio 1.29; 95% confidence interval 1.17-1.42) greater likelihood of infant and neonatal mortality, respectively, when compared with AGA infants from AGA-primed uterus (AGA-AGA; nonswitch). Approximately the same magnitude of risk elevation for neonatal and infant mortality was noted among SGA infants resulting from AGA-primed uterus (a switch) as among SGA infants from SGA-primed uterus (a nonswitch). Overall, the greatest risk of neonatal, infant, and postneonatal mortality was associated with an AGA-SGA switch. CONCLUSION: Fetal programming switch in subsequent gestation adversely affects early survival of affected infants compared with those with no change in fetal growth pattern.     

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.     

Effect of labor on infant morbidity and mortality with preterm premature rupture of membranes: United States population-based study

OBJECTIVE: To evaluate whether labor, in the setting of premature rupture of membranes (PROM), affects infant morbidity and mortality rates. METHODS: We derived data for this population-based cohort study from the United States national linked birth infant death data sets, comprised of singleton live births delivered between 1995 and 1997. We included women (n = 34,594) who had preterm PROM more than 12 hours and delivered between 23 and 32 weeks' gestation. Birth records were used to determine whether delivery occurred with or without labor. Infants with birth weights below the tenth percentile for gestational age were classified as small for gestational age (SGA) on the basis of a nomogram of all singleton births in the United States between 1995 and 1997. Primary outcomes were early neonatal (0-6 days), late neonatal (7-27 days), postneonatal (28-365 days), and infant death (0-365 days). Secondary outcomes included respiratory distress syndrome (RDS), assisted ventilation, and neonatal seizures. Risks of infant mortality and morbidity from labor were examined separately for SGA and non-SGA infants. RESULTS: Overall rates were infant death 11.6%, RDS 15.1%, assisted ventilation 25.9%, and neonatal seizure 0.2%. Labor was associated with higher incidence of early neonatal death in SGA infants (adjusted relative risk [RR] 1.24, 95% confidence interval [CI] 1.11, 1.38) but had no effect on other outcomes. Among non-SGA infants, labor had no effect on infant death but was associated with higher rates of RDS (RR 1.15, 95% CI 1.08, 1.22) and assisted ventilation (RR 1.16, 95% CI 1.08, 1.24). CONCLUSION: Although labor was associated with a slightly higher mortality rate in SGA infants and slightly more respiratory morbidity in non-SGA infants, recommendations regarding clinical treatment should await future clinical trials.     

Patterns and success of fetal programming among women with low and extremely low pre-pregnancy BMI

Purpose  To estimate the frequency of fetal programming phenotypes among women with low BMI and the success of these programming patterns-to determine if small for gestational age (SGA) is a biologically adaptive mechanism to improve chances for infant survival. Methods  We examined the frequency of fetal programming phenotypes: SGA, large for gestational age (LGA), and adequate for gestational age (AGA) among 1,063,888 singleton live births from 1978 to 1997. We also estimated the success of fetal programming phenotypes using neonatal death as the primary study outcome. Results  Underweight gravidas with AGA and LGA babies had elevated risk of neonatal mortality when compared to normal weight mothers, while the risk for neonatal mortality among mothers with SGA babies was reduced. Conclusions  The variation in relative degrees of fetal programming patterns and success observed suggests that underweight mothers are more likely to succeed in programming SGA fetuses rather than any other phenotype.     

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.     

Customised birthweight centiles are useful for identifying small-for-gestational-age babies in women with type 2 diabetes

Background: Customised birthweight centiles identify small-for-gestational-age (SGA) babies at increased risk of morbidity more accurately than population centiles, but they have not been validated in obese populations.
Aims: To compare the rates of SGA by population and customised birthweight centiles in babies of women with type 2 diabetes and examine perinatal outcomes in customised SGA infants.
Methods: Data were from a previous retrospective cohort study detailing pregnancy outcomes in 212 women with type 2 diabetes. Customised and population birthweight centiles were calculated; pregnancy details and neonatal outcomes were compared between groups that delivered infants who were SGA (birthweight < 10th customised centile) and appropriate weight for gestational age (AGA) (birthweight 10–90th customised centile).
Results: Fifteen (7%) babies were SGA by population centiles and 32 (15%) by customised centiles. Two babies of Indian women were reclassified from SGA to AGA by customised centiles. Nineteen babies were reclassified from AGA to SGA by customised centiles; of these, 15 (79%) were born to Polynesian women, five (26%) were born less than 32 weeks and two (11%) were stillborn. Customised SGA infants, compared with AGA infants, were more likely to be born preterm (19 (59%) vs 20 (16%), P  < 0.001) and more likely to be stillborn (4 (13%) vs 0 P  = 0.001). After excluding still births, admission to the neonatal unit was also more common (19 of 28 (68%) vs 43 of 127 (34%), P  < 0.001).
Conclusions: In our population more babies were classified as SGA by customised compared with population centiles. These customised SGA babies have high rates of morbidity.     

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.     

New-onset hypertension in late pregnancy and fetal growth: different associations between singletons and twins.

OBJECTIVE: To compare the effects of new-onset hypertension (NOH) in late pregnancy on fetal growth in singletons and twins. METHODS: A retrospective cohort study was conducted to evaluate the effect of NOH on fetal growth in 17, 720, 900 singletons and 463, 104 twins born in the United States between 1995 and 2000. RESULTS: NOH was associated with lower mean birth weight in both preterm and term singletons. Increased risk of low birth weight and decreased risk of high birth weight was associated with NOH in preterm and term singletons. NOH was associated with increased risk for small-for-gestational-age (SGA) births and decreased risk for large-for-gestational-age (LGA) births in preterm singletons, whereas it was associated with increased risk of both SGA and LGA births in term singletons. NOH was associated with higher mean birth weight in early preterm twins, and lower mean birth weight in term twins. Decreased risk for low birth weight was found in the NOH group among early preterm twins, and increased risk for low birth weight in term twins. NOH was associated with increased risk of SGA births and decreased risk for large-for-gestational-age (LGA) births in early preterm twins, while increased risk of SGA births in term twins. CONCLUSION: NOH is associated with slower fetal growth in singletons delivered at different gestational ages, but the effect varies in twins depending on gestational age at delivery with faster growth in early preterm twins.     

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 effects of labor on infant mortality among small-for-gestational-age infants in the USA

Objective: To determine whether the presence of labor affects infant mortality among small-for-gestational-age (SGA) infants. Methods: Data were derived from the United States national linked birth/infant death data sets for 1995–97. Singleton SGA live births in cephalic presentation delivered at 24–42 weeks' gestation were included. Mortality rates for SGA infants exposed and unexposed to labor were compared, and relative risks (RR) were derived using multivariable logistic regression models, after adjusting for potential confounding factors. Results: Of 986 405 SGA infants, 87.4% were exposed to labor. Infants exposed to labor at 24–31 weeks had greater risks of dying during the early neonatal period (RR 1.79-1.86). Decreased risks of late and postneonatal death were observed at all gestational ages in the presence of labor. Conclusions: Exposure to labor is associated with an increased risk of early neonatal death among SGA infants, especially at gestational ages below 32 weeks. Future randomized trials are warranted to determine the optimal obstetric management of these high-risk infants.     

Trends in fetal growth among singleton gestations in the United States and Canada, 1985 through 1998

We examined trends in fetal growth among singleton live births in the United States and Canada. The data files (n = 48,637,680; 16.6% blacks) for US births, and the Canadian Birth Database of Statistics Canada (n = 3,167,702) for Canadian births were used. Trends were assessed between 1985-86 and 1997-98 with reference to mean birthweight, birthweight-for-gestational-age z-score, and proportions delivered low birthweight (< 2,500 g), small for gestational age (SGA: birthweight < 10th centile for gestational age) and large for gestational age (LGA: birthweight > 90th centile). The term "mean birth weight" increased in the US and Canada between 1985 and 1998, as have the mean z-score. Rates of term SGA births declined among US (11% among whites and 12% among blacks) and Canadian births (27%). Preterm SGA births increased by 3% and 17%, respectively, among US whites and blacks, but declined by 11% among Canadian births. Further, term LGA births increased in the US (5% among whites and 9% among blacks) and Canada (24%). Preterm LGA births declined by 13%, 25%, and 14% among US whites and blacks, and Canadian births, respectively. These findings suggest that US and Canadian babies are getting bigger. The role of preterm obstetrical induction and preterm cesarean delivery are likely to have influenced these trends.     

Adverse perinatal outcome and maternal risk factors in population versus customized defined SGA babies

Objective.?The purpose of this study was to compare population and customized-based birth weight centiles in their association with perinatal outcome and maternal risk factors, in nulliparous Caucasian women in a socio-economic disadvantaged region.

Methods.?We analyzed perinatal outcomes in births of 302 Caucasian women of which 155 were small for gestational age (SGA) and 147 were appropriate for gestational age (AGA). Out of the overall study group, two cohort studies were designed. One was classified by population centiles as either SGA (n= 133) or AGA (n?= 169) and the other was classified by customized centiles as either SGA (n?= 131) or AGA (n?= 172). Maternal risk factors and operative delivery rates for fetal distress, Apgar scores, need for resuscitation and neonatal nursery care given, were determined for both customized and population-based SGA babies.

Results.?The customized SGA only group showed more mental health problems and special nursery in comparison with the AGA group. The population SGA only group had more smoking and mental health problems than the AGA group, but no differences on neonatal outcome measures.

Conclusion.?Use of customized centiles does identify an additional group neonates with a significantly higher need for special nursery admission in a homogeneous ethnic Caucasian group.     

Gestational age-specific normal birth weight for Japanese twins. Risk of early neonatal death in small-for-gestational-age and large-for-gestational-age twins.

OBJECTIVE: To construct nomograms for birth weight in Japanese twins and to investigate the risk of early neonatal death (death within seven days of birth) in small-for-gestational-age (SGA) and large-for-gestational-age (LGA) twins as compared with appropriate-for-gestational-age (AGA) twins. STUDY DESIGN: Of 89,253 infants born at > or = 24 weeks of gestation to women with multifetal pregnancies (96% twins) between 1989 and 1993 in Japan, 1,804 were stillborn, and 891 died within seven days of birth (early neonatal death [END] group). The remaining 86,558 infants were defined as the normal group. We constructed growth curves for the normal and END groups and compared the incidence of early neonatal death among the SGA, AGA and LGA infants. RESULTS: Birth weights in the END group were similar to those in the normal group until 33 weeks of gestation, but was lower than the birth weights of the normal group after 33 weeks. Both SGA and LGA infants had an increased risk of death within 7 days of birth as compared with AGA infants throughout gestation. CONCLUSION: Both SGA and LGA twins were at increased risk of death as compared with AGA twins. We recommend the use of birth weight nomograms in the management of twin pregnancies.     

Teenage pregnancies and risk of late fetal death and infant mortality.

OBJECTIVE: To estimate the effect of low maternal age on late fetal death and infant mortality and to estimate the extent of any increase in infant mortality attributable to higher rates of preterm birth among teenagers. DESIGN: Population-based cohort study. SETTING: Births recorded in the nationwide Swedish Medical Birth Registry. POPULATION: All single births to nulliparous women aged 13-24 years (n = 320,174) during 1973-1989. METHODS: Using information recorded in the medical birth registry, linked to a national education register, the effect of low maternal age on adverse outcomes was estimated using logistic regression analysis. MAIN OUTCOME MEASURES: Late fetal death, neonatal and postneonatal mortality and preterm birth. RESULTS: Compared with mothers aged 20-24 years, adjusted risks of neonatal and postneonatal mortality were significantly increased among mothers aged 13-15 years (odds ratios = 2.7 and 2.6, respectively) and among those aged 16-17 years (odds ratios = 1.4 and 2.0, respectively), while mothers aged 18-19 years had a significant increase in risk of postneonatal mortality only (odds ratio = 1.4). Rates of very preterm birth (< or = 32 weeks), according to maternal age, were: 13-15 years, 5.9%; 16-17 years, 2.5%; 18-19 years, 1.7%; and 20-24 years, 1.1%. The high rates of very preterm birth among young teenagers almost entirely explained the increased risk of neonatal mortality in this group. CONCLUSIONS: The increased risks of neonatal and postneonatal mortality among young teenagers may be related to biological immaturity. The increase in risk of neonatal mortality is largely explained by increased rates of very preterm birth.     

Neonatal transverse cerebellar diameter in normal and growth-restricted infants

OBJECTIVE: To assess the transverse cerebellar diameter (TCD) in preterm and term neonates with normal growth or growth restriction. METHODS: TCD was sonographically measured after birth in 404 neonates born between 23 and 42 weeks of gestation. The study included two groups: Group 1: 334 appropriately grown for gestational age (AGA) neonates (both birthweight (BW) and head circumference (HC) were between the 3rd and 97th centiles), which were subdivided into two subgroups according to the HC measurements. Group 2: 70 small for gestational age (SGA) neonates (BW <3rd centile), were further divided into three subgroups according to HC measurements. RESULTS: In Group 1 of AGA neonates, a linear growth function was observed between the TCD and GA (R = 0.914, P < 0.00001, TCD = 0.279 + 0.142 X GA), and between TCD and HC (R = 0.886, P < 0.00001, TCD = -0.333 + 1.777 X HC). The percentage of neonates with normal TCD (> or =10th centile) was more than 85% of the AGA and asymmetric SGA subgroups, and 60.7% of the microcephalic SGA subgroup (P < 0.02). CONCLUSIONS: This study provides normative data of neonatal TCD across gestational age. TCD measurement via sonography is a new adjunctive criterion for objectively assessing gestational age in infants when a precise determination of gestational age is necessary. This is very important since utility of the TCD is effective for both AGA and asymmetric SGA infants.     

A method for quantifying birthweight discordance in quadruplets and potential use in predicting early mortality

We describe an approach to quantify birthweight discordance in quadruplets and assessed its potential use in predicting infant mortality. Retrospective cohort study on quadruplets delivered in the United States from 1995 through 2000 inclusive. The main outcome measures were infant, neonatal, and postneonatal mortality. A total of 2692 quadruplet live births (673 complete clusters) with complete information on gestational age, birthweight, and survival within the first year. Of the total 673 quadruplet clusters, discordance occurred in 180 sets (26.7%). The predominant discordant type was a single discordant individual within a cluster (177 sets or 99.8%), whereas only three sets (0.2%) recorded up to two discordant quadruplets within a cluster. The period of pronounced risk for the occurrence of birthweight discordance was between 28 and 35 gestational weeks. Discordant individuals exhibited elevated risk for infant (adjusted odds ratio [aOR] = 2.1; 95% confidence interval [CI], 1.4 to 3.0), neonatal (aOR = 1.8; 95% CI, 1.2 to 2.6), and postneonatal (aOR = 2.9; 95% CI, 1.1 to 8.4) mortality. After adjusting for small for gestational age, the risk for postneonatal mortality among discordant infants quadrupled (aOR = 4.1; 95% CI, 1.5 to 10.8). The population-attributable risks were 18, 20, and 46% for neonatal, infant, and postneonatal mortality, respectively. The new method is predictive of mortality at all stages of infancy. Discordance accounts for 18 to 46% of all quadruplet deaths during infancy in the United States.     

Risk factors and neonatal/infant mortality risk of small-for-gestational-age and preterm birth in rural Nepal

Objective: Our study seeks to elucidate risk factors for and mortality consequences of small-for-gestational-age (SGA) and preterm birth in rural Nepal. In contrast with previous literature, we distinguish the epidemiology of SGA and preterm birth from each other.

Methods: We analyzed data from a maternal micronutrient supplementation trial in rural Nepal (n?=?4130). We estimated adjusted risk ratios (aRR) for risk factors of SGA and preterm birth, and aRRs for the associations between SGA/preterm birth and neonatal/infant mortality. We used mutually exclusive categories of term-appropriate-for-gestational-age (AGA), term-SGA, preterm-AGA, and preterm-SGA (with term-AGA as reference) in our analyses.

Results: Stunted (<145?cm) and wasted (<18.5?kg/m²) women both had increased risk of having term-SGA (aRR 1.36, 95% CI: 1.14-1.61, aRR 1.22, 95% CI: 1.09–1.36 respectively) and preterm-SGA (aRR 2.48, 95% CI: 1.29–4.74, aRR 1.99, 95% CI: 1.33–2.97 respectively), but not preterm-AGA births. Similar results were found for low maternal weight gain per gestational week. Those born preterm-SGA generally experienced the highest neonatal and infant mortality risk, although term-SGA and preterm-AGA newborns also had statistically significantly high mortality risks compared to term-AGA babies.

Conclusions: SGA and preterm birth have distinct risk factors and mortality patterns. Maternal chronic and acute malnutrition appear to be associated with SGA outcomes. Because of high SGA prevalence in South Asia and the increased neonatal and infant mortality risk associated with SGA, there is an urgent need to intervene with effective interventions.     

早发型重度子痫前期早产婴儿存活影响因素分析

目的探讨早发型重度子痫前期早产儿婴儿期存活的影响因素。方法对比分析2001年1月至2006年5月在北京大学第三医院分娩的孕周〈34周的早发型重度子痫前期活产早产儿与随机抽取的同时期孕周匹配的自发性早产活产早产儿婴儿期结局,并进行多因素分析。结果研究组活产新生儿86例,随访71例（82.6%）;对照组活产新生儿114例,随访96例（84.2%）。研究组婴儿期死亡15例（21.1%）,其中早期新生儿期死亡12例（16.9%）;对照组婴儿期死亡10例（10.4%）,早期新生儿期死亡5例（5.2%）。研究组早期新生儿期死亡率明显高于对照组（P=0.014）,两组间婴儿期死亡率差异无统计学意义（P〉0.05）。多因素分析显示,是否入住NICU实施积极救治是影响早产儿婴儿期死亡率的主要因素（OR 0.016,95%CI 0.002-0.113）。当去除NICU因素,孕龄和有无新生儿窒息是影响早发型重度子痫前期早产儿婴儿期死亡率的主要因素（OR 0.516,95%CI 0.296-0.902;OR 5.363,95%CI 1.703-16.891）。结论早发型重度子痫前期是早产儿早期新生儿期死亡的影响因素,孕龄和新生儿窒息是影响早发型重度子痫前期婴儿期生存率的主要因素。家属救治态度以及NICU在改善高危儿预后方面有重要影响。重度子痫前期作为独立因素不增加34孕周前早产儿的婴儿期不良结局风险,对早发型重度子痫前期患者进行保守治疗可以改善婴儿预后,降低婴儿丢失率,家属救治意愿是不可忽视的因素。     

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.