孕期妇女全血5种微量元素的测定

摘要:目的　了解不同孕期妇女外周血铜、锌、钙、镁、铁元素水平的变化。方法　选取2012年7月-2014年6月在我院进行孕前、妊娠及产后体检的20～35岁健康女性为研究对象,选择孕前样本100例,妊娠样本900例（4周为一孕期,每孕期100例）,产后样本收集69例,以原子吸收光谱法测定外周血5种元素含量。结果　血铜水平与孕期正相关（r＝0.388,P＜0.01）,产后下降接近孕前。孕前、孕4～8周及产后血铜水平显著低于其他孕期（-462.09＜H＜-257.67,P＜0.001）。血锌水平孕20周前与孕期负相关（r＝-0.218,P＜0.01）,孕20周后与孕期正相关（r＝0.106,P＜0.01）;血锌水平在产后显著高于孕前～孕32周各期（-373.42＜H＜-193.76,P值介于0.000～0.003）,在孕37～40周显著高于孕4～24周各期（-278.45＜H＜-155.18,P值介于0.000～0.021）,在孕33～36周显著高于孕9～24周各期（-226.90＜H＜-149.10,P值介于0.000～0.035）,在孕前（H分别为160.68,155.39,P值分别为0.013,0.020）及孕29～32周（H分别为-179.66,-174.37,P值分别为0.002, 0.004）高于孕13～20周各期。血镁水平与孕期负相关（r＝-0.165,P＜0.01）,产后恢复至孕前。血镁水平在孕前（156.69＜H＜181.90,P值介于0.002～0.018）、孕4～8周（151.22＜H＜176.43,P值介于0.003～0.029）及产后-211.75＜H＜-186.54,P值介于0.001～0.006）高于孕37～40周及孕17～32周各期,在产后高于孕33～36周（H＝-167.22,P＝0.03）。血铁水平与孕期负相关（r＝-0.264,P＜0.01）,孕33周后逐步恢复。血铁水平在孕前高于孕9～40周各期（163.42＜H＜322.71,P值介于0.000～0.010）,在孕4～8周高于孕17～40周各期（170.15＜H＜228.42,P值介于0.000～0.005）,在孕9～12周高于孕21～28周各期（148.96＜H＜159.29,P值介于0.036～0.015）,在产后分别高于孕21～28周（-187.16＜H＜-176.83,P值介于0.006～0.014＜0.05）及孕33～36周（H＝-166.03,P＝0.032）。不同孕期妇女血钙水平无统计学差异（P＝0.098）。结论　血铜在孕期增高,血镁水平在孕17～32周达到最低,血铁在21～36周达到最低,血锌在孕20周达到最低。妊娠期微量元素的补充应根据该元素在孕期的变化规律有所侧重。     

The influence of age at exposure to PBBs on birth outcomes

The determination of critical windows of susceptibility to environmental chemical exposures and health has become a major public health focus. This study examined the association between early age at exposure to polybrominated biphenyls (PBBs) and subsequent birth weight and gestational length in offspring among females. The study population consisted of 1111 births that occurred among 560 women enrolled in the Michigan PBB Cohort from 1975 to 1994. Maternal age at exposure was categorized into three groups:<10 years (n = 64), 11-16 years (n = 149), and 17-42 years (n = 347). Overall serum PBB levels ranged from 0 to 1490 ppb, with a median of 2, 3, and 2 ppb in the three age groups, respectively. Separate mixed-effects linear regression models were used to evaluate the effect of age at exposure (years) and initial PBB level (ppb) on birth weight (grams) and gestational age (weeks), controlling for gestational age (weeks) (in the model examining effects on birth weight), BMI (kg/m(2)) and serum PCB level at enrollment (ppb), maternal age and paternal education at delivery, parity, infant gender, interval between the initial serum test and date of delivery (years), and the trimester in which prenatal care was initiated. Relative to the oldest age group, age<10 years at exposure was the most important predictor of increased birth weight (estimated regression coefficient = 225 g, P = 0.012). Infant birth weight increased approximately 16 g for every 10 ppb increase in serum PBBs (P=0.004). There was no association between initial PBB levels and gestational age, nor were initial serum PCB levels associated with either infant birth weight or gestational length. These results provide support for the hypothesis that early age at exposure may be an important determinant in subsequent health effects due to environmental chemical exposures.     

Factors associated with the timing of abortions

The timing of an abortion (often measured as gestational age) can have important effects on the woman's physical health and on the cost of the procedure. To the authors' knowledge, there has been only one national analysis of the factors associated with the gestational age at abortion, but it employed data from over 20 years ago. The state‐specific studies that have explored abortion timing have typically examined the effects of a specific change in abortion regulations. In this study, we employ annual, state‐level data covering the 1991–2014 period that measure the frequency of abortions by gestational age. We regress these measures of abortion utilization on policy, economic, demographic, and health care infrastructure characteristics. The estimates indicate that the introduction of state restrictions on Medicaid funding of abortions is associated with a 13% increase in the rate of abortions after the first trimester. We do not find a statistically significant association between parental involvement laws and the rate or percentage of post‐first‐trimester abortions.     

Comparative Effectiveness of Group and Individual Prenatal Care on Gestational Weight Gain

This study examined differences in gestational weight gain for women in CenteringPregnancy (CP) group prenatal care versus individually delivered prenatal care. We conducted a retrospective chart review and used propensity scores to form a matched sample of 393 women (76 % African-American, 13 % Latina, 11 % White; average age 22 years) receiving prenatal care at a community health center in the South. Women were matched on a wide range of demographic and medical background characteristics. Compared to the matched group of women receiving standard individual prenatal care, CP participants were less likely to have excessive gestational weight gain, regardless of their pre-pregnancy weight (b = ?.99, 95 % CI [?1.92, ?.06], RRR = .37). CP reduced the risk of excessive weight gain during pregnancy to 54 % of what it would have been in the standard model of prenatal care (NNT = 5). The beneficial effect of CP was largest for women who were overweight or obese prior to their pregnancy. Effects did not vary by gestational age at delivery. Post-hoc analyses provided no evidence of adverse effects on newborn birth weight outcomes. Group prenatal care had statistically and clinically significant beneficial effects on reducing excessive gestational weight gain relative to traditional individual prenatal care.     

Prevalence and Predictors of Back-Transport Closer to Maternal Residence After Acute Neonatal Care in a Regional NICU

Objectives To describe the demographics, clinical characteristics and referral patterns of premature infants to a regional level IV neonatal intensive care unit (NICU); to determine the prevalence and predictors of back-transport of infants?≤?32 weeks gestational age in a level IV NICU; for infants not back-transported closer to maternal residence, determine the length of stay beyond attainment of clinical stability. Methods Data (2010–2014) from the Children’s Hospital Neonatal Database and individual chart review for infants?≤?32 weeks admitted to a level IV NICU whose maternal residence was outside the metro area were included. Bivariate associations of maternal and infant characteristics with back-transport were estimated using two-sample t tests and Fisher’s exact test. Multivariable logistic regression was used to measure independent predictors of back-transport. Clinical stability was defined as the attainment of full volume enteral feedings and low flow nasal cannula. Results A total of 223 infants were eligible for analysis; of whom 26% were back-transported after acute care. In the adjusted analysis, insurance status, distance from maternal residence and gestational age were significantly associated with back-transport. For infants not back-transported closer to maternal residence, median length of stay in the level IV NICU beyond attainment of clinical stability was 28.5 days. Conclusion for Practice Predictors of back-transport include private insurance, greater distance of maternal residence from NICU and younger gestational age. Many preterm infants admitted to a regional NICU for acute care remained hospitalized in a level IV NICU after achieving clinical stability, for which care in a NICU closer to maternal residence may be appropriate.

     

Estimation of individual neonatal survival using birthweight and gestational age: a way to improve neonatal care

The study was conducted to determine the combined effect of birthweight and gestational age at birth on neonatal mortality using individually-identified livebirths. Logistic regression was used for studying the interactive effect of birthweight and gestational age on the individual probability of neonatal death. All livebirths from Chile in 2000 were included in a linked file. Odds ratio models for birthweight and gestational age were developed for each sex. The probability of neonatal death by sex was presented using contour plots. The models were statistically significant, and odds ratios were different and non-linear for the effects of birthweight and gestational age. Contour plots of constant neonatal mortality according to birthweight and gestational age were presented; they were similar for each sex. A single graph for both sexes that estimates the survival potential of infants born too early or too small would improve neonatal care in developing countries.     

The Impact of Symptoms of Depression and Walking on Gestational Age at Birth in African American Women

BackgroundSymptoms of depression have been related to lower gestational age and preterm birth (<37 completed weeks gestation). Leisure time physical activity may have protective effects on preterm birth; however, less has been published with regard to other domains of physical activity such as walking for a purpose (e.g., for transportation) or the pathways by which symptoms of depression impact gestational age at birth.MethodsThis was a secondary analysis of available data of African American women. Women were interviewed within 3 days after birth. We proposed a model in which walking for a purpose during pregnancy mediated the effects of symptoms of depression (measured by the 20-item Center for Epidemiologic Studies-Depression [CES-D] scale) on gestational age at birth in a sample of 1,382 African American women.ResultsUsing structural equation modeling, we found that the direct effect of CES-D scores of 23 or greater, which have been correlated with major depression diagnosis, on gestational age at birth was -4.23 (p < .001). These results indicate that symptoms of depression were associated with a decrease in gestational age at birth of 4.23 days. Walking for a purpose mediated the effect of CES-D scores of 23 or greater on gestational age at birth.ConclusionsCompared with African American women without symptoms of depression, African American women who had symptoms of depression walked less for a purpose during their pregnancy and delivered infants with lower gestational age at birth. If not medically contraindicated, clinicians should incorporate walking as part of prenatal care recommendations and reassure women about safety of walking during pregnancy.     

Gestational weight gain and its related social and demographic factors in health care settings of rural and urban areas in northwest Iran

The current study was aimed to evaluate gestational weight gain and its socio-demographic determinants among pregnant women in north-west of Iran. In the current cross-sectional study, four hundred eighty one pregnant women aged 26.12 ± 7.45 years were enrolled. Data on pre-pregnancy weight, height, age, educational attainment, parity, household size, hemoglobin status and total pregnancy weight gain were extracted from routine health center records. The pregnant women were categorized based on their pre-pregnancy body mass index (BMI) as underweight, normal weight and overweight or obese according to the 2009 Institute of Medicine (IOM) recommendations. Participants were also classified according to their educational level into three ‘some school’, ‘high school’ and ‘college’ groups. Gestational weight gain in 27.6% of pregnant women was in normal IOM recommended range; while, weight gain in 49% and 23.2% of pregnant women was below and above recommended range respectively. Women with high educational attainment (≥12 years) have significantly higher weight gain compared with low-educated women (<12 years) (P < 0.001). Age was in negative relationship with gestational weigh gain even after adjusting for confounder effects of residency, educational attainment and household size (r = 0.2, P < 0.001). Our data showed a high prevalence of abnormal gestational weight gain in pregnant women attending to public health centers in northwest of Iran. Moreover educational level, parity and age were significant determinants of gestational weight gain in pregnancy. Special attention should be focused on prenatal nutritional status and health care programs in current health care services in Iran.     

孕产妇暴露因素与小于胎龄儿关系的研究现状

本文通过文献研究,简述了孕产妇暴露因素与小于胎龄儿（SGA）的国内外的研究现状,分析并总结了SGA的结局及其与孕产妇暴露因素之间的关系,为降低SGA的发生、实现优生优育提供重要指导和参考。     

新生儿脐带血促肾上腺皮质激素、皮质醇水平的影响因素研究

目的 分析健康足月儿促肾上腺皮质激素(ACTH)、皮质醇(COR)的水平及其影响因素,为新生儿的预防保健提供理论支持。方法 选取2018年10月-2019年2月空军医学特色中心妇产科出生的88例新生儿为研究对象,检测脐带血ACTH、COR水平,用最优尺度回归分析的方法探讨分娩方式、胎龄、性别、出生体重、母亲孕期情况对新生儿脐带血ACTH、COR水平的影响。结果 88例新生儿脐带血ACTH水平为(172.11±93.93)pg/ml,COR水平为(310.05±125.33)ng/ml。单因素分析结果显示,不同分娩方式、胎龄的新生儿脐带血COR水平的差异具有统计学意义(P＜0.01),而不同性别、出生体重、母亲孕期健康情况的新生儿COR水平差异无统计学意义,不同分娩方式、胎龄、性别、出生体重、母亲孕期情况的新生儿的ACTH水平差异无统计学意义(P>0.05)。最优尺度回归分析显示,分娩方式、性别、胎龄和体重对脐带血COR的水平有显著影响(β=-0.522,-0.221,0.284,-0.260,P＜0.05)。结论 分娩方式、胎龄是健康足月儿脐带血COR水平的主要影响因素,而本研究所涉及的胎龄、性别、出生体重、母亲孕期情况等均不影响ACTH水平。     

Neonatal risk mortality scores as predictors for health-related quality of life of infants treated in NICU: a prospective cross-sectional study

Purpose

To determine the relationship of Apgar scores, gestational age and neonatal risk mortality scores to health-related quality of life (HRQoL) for infants at the age of 8 months treated after birth in neonatal intensive care unit (NICU).

Methods

All surviving infants treated in two-third level NICUs in Rijeka, Croatia (from August 2013 to August 2014) were included in this prospective, cross-sectional study. For all neonates, the Score for Neonatal Acute Physiology (SNAP), SNAP with Perinatal Extension (SNAP-PE) and their simplified modifications (SNAP II and SNAP-PE II) were calculated. At the corrected age of 8 months, the Pediatric Quality of Life Questionnaire (PedsQL)—infant scale—was completed by parents of surviving infants. Multiple regression analysis was performed in order to assess the value of neonatal risk mortality scores, Apgar scores and gestational age as possible predictors of HRQoL, measured by questionnaire score.

Results

A strong correlation has been found between SNAP and 5-min Apgar scores to HRQoL. A positive correlation was also found between gestational age and HRQoL.

Conclusion

SNAP and 5-min Apgar scores are important outcome indicators, can aid clinicians’ and parents’ decision making on the benefits and burdens of acute medical interventions and help determine quantities of medical treatment. Educated medical staff, effective and efficient medical treatment and a high quality of care which prevent adverse events in the first minute of life should be a priority in efforts to improve the future quality of life.

     

Prenatal care utilization: its measurement and relationship to pregnancy outcome

This study proposes a redesigned measure of prenatal care utilization based on modifications made to a preexisting index of the adequacy of such care. Six prenatal care utilization groups were delineated: intensive, adequate, intermediate, inadequate, no-care, and missing/unknown. Using 430,349 cases from South Carolina and North Carolina vital records from 1978 to 1982 (live birth-infant death cohort files for white resident mothers), this proposed prenatal care utilization measure was examined by maternal sociomedical risk characteristics (age-parity, marital status, education, complications of pregnancy, and previous pregnancy terminations) and by pregnancy outcomes (birth weight, gestational age, and birth weight- and gestational age-specific neonatal mortality). The intensive prenatal care group had relatively more pregnancy complications but also the most preferred pregnancy outcomes. Appreciable differences in birth weight and gestational age distributions were observed among the prenatal care categories within maternal risk status groups. Increased utilization of prenatal care was associated with higher mean birth weight and gestational age. However, after controlling for maternal risk status, an appreciable variation in birth weight- and gestational age-specific neonatal mortality was not apparent across prenatal care groups.     

Abortion barriers and perceptions of gestational age among women seeking abortion care in the latter half of the second trimester

Objective

Later second-trimester abortion (gestational age ≥ 19 weeks) is higher risk, more expensive and more difficult to access than abortion earlier in pregnancy. We sought to enumerate barriers to care described by women seeking abortion in the latter half of the second trimester. We also assessed the accuracy of later second-trimester abortion patients’ perceptions of their pregnancies’ gestational ages.

Study Design

A retrospective analysis of data from 232 women served by a referral program for women seeking abortion care between 19 and 24 weeks of gestational age was performed. Data collected included demographics, pregnancy history, gestational age by ultrasound, perceived gestational age, barriers to abortion care experienced and time lapsed from pregnancy recognition to presentation for care.

Results

Difficulty deciding whether to terminate (44.8%), financial barriers to care (22.0%) and the patient having recently realized she was pregnant (21.6%) were the most common delaying barriers cited. Nearly half (46.6%) of women underestimated their own gestational ages by greater than 4 weeks. Risk factors for experiencing at least 3 months time lapsed from pregnancy recognition to program referral included difficulty deciding whether to terminate [odds ratio (OR) 4.08, 95% confidence interval (CI) 2.51–8.70] and nonwhite race/ethnicity (OR 2.04, 95% CI 1.16–3.57).

Conclusions

Women seeking abortion care in the latter half of the second trimester encounter many of the same barriers previously identified among other abortion patient populations. Because many risk factors for delayed presentation for care are not amenable to intervention, abortion must remain available later in the second trimester.

Implications

Women presenting for abortion in the later second trimester are delayed by structural and individual-level barriers, and many substantially underestimate their own gestational age. Removing financial barriers may help reduce abortion delay; however, many risk factors are nonmodifiable, underscoring the need to ensure access to later second-trimester abortion.     

孕妇社会学特征对新生儿出生体重和身长的影响

目的:探讨孕妇社会学特征及相关因素对新生儿出生体重和身长的影响,为降低低出生体重儿和巨大儿的发生、建立孕期保健临床护理路径提供依据。方法:由专人调查分娩孕妇的一般情况、年龄、职业、受教育程度、孕期居住地、孕次、产前保健次数等指标,孕妇分娩后立即测量新生儿体重和身长。结果:新生儿出生体重及身长与孕妇年龄、孕次无统计学关联。新生儿出生体重及身长在不同职业组间差异具有统计学意义(F=6.84,P=0.0 012;F=3.98,P=0.0 192);新生儿出生体重及身长在不同受教育程度组间差异具有统计学意义(F=5.27,P=0.0 014;F=4.37,P=0.0 047;)新生儿出生体重与孕妇居住地具有统计学关联(t=2.57,P=0.0 108);新生儿出生身长与孕妇居住地无统计学关联(t=1.69,P=0.0 922)。新生儿出生体重和身长在不同产前保健次数的孕妇组间有统计学差异(F=10.07,P<0.0 001;F=9.55,P<0.0 001)。结论:孕妇年龄和孕次未影响新生儿出生体重和身长;受教育程度、孕妇的职业、居住地、产前保健次数可以不同程度地影响新生儿出生体重和身长。应重视孕妇社会学特征及相关因素对新生儿出生体重和身长的影响,并提供适时干预。     

Perinatal risk and severity of illness in newborns at 6 neonatal intensive care units

OBJECTIVES: This multisite study sought to identify (1) any differences in admission risk (defined by gestational age and illness severity) among neonatal intensive care units (NICUs) and (2) obstetric antecedents of newborn illness severity. METHODS: Data on 1476 babies born at a gestational age of less than 32 weeks in 6 perinatal centers were abstracted prospectively. Newborn illness severity was measured with the Score for Neonatal Acute Physiology. Regression models were constructed to predict scores as a function of perinatal risk factors. RESULTS: The sites differed by several obstetric case-mix characteristics. Of these, only gestational age, small for gestational age. White race, and severe congenital anomalies were associated with higher scores. Antenatal corticosteroids, low Apgar scores, and neonatal hypothermia also affected illness severity. At 2 sites, higher mean severity could not be explained by case mix. CONCLUSIONS: Obstetric events and perinatal practices affect newborn illness severity. These risk factors differ among perinatal centers and are associated with elevated illness severity at some sites. Outcomes of NICU care may be affected by antecedent events and perinatal practices.     

Consequences of sociodemographic inequalities on birth weight

OBJECTIVE: To analyze sociodemographic inequalities in prenatal and childbirth care and their consequences on birth weight. METHODS: The study was based on a sample of 10,072 postpartum women treated at public (those outsourced by the National Health System) and private maternity hospitals in Rio de Janeiro, Brazil, from 1999 to 2001. To test the association between birth weight and maternal sociodemographic and biological characteristics and prenatal care (modified Kotelchuck index), postpartum women were stratified by level of schooling and two multiple linear regressions were performed. The bootstrap technique was used in addition to accurate confidence intervals for the estimated effects. RESULTS: For nearly all of the variables analyzed in the bivariate analysis, birth weight was lower among children of mothers with low schooling. In the multivariate analysis, among women with low schooling, there was a direct association between birth weight and the modified Kotelchuck index and gestational age. The variables black skin color, smoking, and history of premature birth were negatively associated with birth weight, while maternal age and parity showed distinct behaviors from the central range of data at the extremes. In the group with high schooling, only parity, gestational age, and modified Kotelchuck index were significant and directly associated with birth weight. The protective effect of prenatal care was observed, as well as the negative effect of smoking, regardless of the mother's level of schooling. CONCLUSIONS: The variables associated with neonates' birth weight of mothers with high schooling in Rio de Janeiro were biological, in contrast to the social determinants in the group with low schooling.     

小于胎龄儿围产期相关高危因素分析

目的:探讨与小于胎龄儿出生相关的围产期高危因素。方法:对2008年8月~2010年7月在儿科新生儿病房住院的71例小于胎龄儿进行回顾性调查和统计学分析,研究与小于胎龄儿发生可能有关的各种危险因素。结果:①位于前3位的相关致病因素分别是孕母患妊娠期高血压疾病、患儿风疹病毒IgM阳性以及孕母文化水平较低;②在风疹病毒IgM阳性及阴性两组患儿中,出生体重、头围、重量指数、身长/头围以及先天畸形发生率的差异均无统计学意义;③部分风疹病毒IgG阳性孕妇可再次受到感染,有可能对胎儿造成损害。结论:积极治疗孕母疾病,加强产前保健,减少围产期相关高危因素是降低小于胎龄儿出生的关键。     

Denial of Abortion Because of Provider Gestational Age Limits in the United States

Objectives. We examined the factors influencing delay in seeking abortion and the outcomes for women denied abortion care because of gestational age limits at abortion facilities.Methods. We compared women who presented for abortion care who were under the facilities’ gestational age limits and received an abortion (n = 452) with those who were just over the gestational age limits and were denied an abortion (n = 231) at 30 US facilities. We described reasons for delay in seeking services. We examined the determinants of obtaining an abortion elsewhere after being denied one because of facility gestational age limits. We then estimated the national incidence of being denied an abortion because of facility gestational age limits.Results. Adolescents and women who did not recognize their pregnancies early were most likely to delay seeking care. The most common reason for delay was having to raise money for travel and procedure costs. We estimated that each year more than 4000 US women are denied an abortion because of facility gestational limits and must carry unwanted pregnancies to term.Conclusions. Many state laws restrict abortions based on gestational age, and new laws are lowering limits further. The incidence of being denied abortion will likely increase, disproportionately affecting young and poor women.The majority of abortions in the United States are in the first trimester of pregnancy, but 8.5% (approximately 100 000) occur after 13 weeks’ gestation.1 Most women having second trimester abortions would have liked to have had the procedure earlier,2 and women report a number of delaying factors, including cost and access barriers and late detection of pregnancy.2–4 These delays can result in women being denied care because they present with pregnancies beyond an abortion provider’s gestational age limit and are unable to obtain an abortion elsewhere. (An “abortion provider” is a facility where abortions are performed.5) Little is known about how frequently this occurs and what happens to women denied abortion care.The 1973 Supreme Court Roe v. Wade6 decision established the point of potential fetal viability as the threshold after which states could restrict women’s access to abortion care as long as they allowed for exceptions to preserve the life and health of the pregnant woman. However, Roe v. Wade did not specify a gestational age for viability. Many states have established an upper gestational limit, most commonly after 24 weeks from a woman’s last menstrual period, and some states have done so without the required exceptions.7 At least 8 states have recently reduced or plan to reduce the upper gestational limit to 20 weeks, and 1 state to 18 weeks.8 Individual abortion providers can set their limits at lower gestational ages, and do so based on the availability of trained physicians, clinician and staff comfort, and facility regulations. According to a national survey of abortion providers, 23% offer abortions after 20 weeks’ gestation, and 11% do so at 24 weeks.5 Because fewer providers offer abortion care after the first trimester, women must travel longer distances to obtain later abortions. Because later abortions are more complex procedures, often occurring over 2 or more days, they are also more costly; the average charge for an abortion at 10 weeks is $543 compared with $1562 for an abortion at 20 weeks.5 Some women must also arrange for childcare, take time off work or other responsibilities, and incur transportation and hotel expenses; raising these funds results in additional delays.9We sought to describe the characteristics associated with being turned away because of provider gestational age limit, and the efforts such women make to obtain a desired abortion. Additionally, we explored the factors associated with obtaining a desired abortion elsewhere. Finally, we estimated the incidence of women being denied an abortion in the United States because of provider gestational limits.     

Racial differences in temporal changes in newborn viability and survival by gestational age

This study examines trends in the rates of very preterm, moderately preterm and gestational age-specific neonatal mortality, and in the gestational age limit of viability in South Carolina (SC) from 1975 to 1994. We also investigate whether trends were similar between African-Americans and Whites. We hypothesised that disproportionate reductions in gestational age-specific mortality, rather than any major changes in the gestational age distributions of either race group, underlie any increasing racial disparity in overall mortality rates. During 1975-94, single livebirths, who were born to mothers resident in SC and were either White or African-American based on recorded maternal race, were selected for the investigation. We define the gestational age limit of viability as the gestational age at which > or = 50% of infants in the population died within 28 days of life. Although preterm percentages have not improved, there was a marked decline in neonatal mortality. Gestational age-specific neonatal mortality decreased for both race groups, although there were greater reductions for White preterm infants. By the end of the study period, the African-American neonatal mortality rate was 2.3 times that of Whites and the gestational age at which 50% of newborns died within 28 days of life was 24.5 weeks for Whites and 23.9 weeks for African-Americans. The ongoing decline in neonatal mortality continues to be mainly due to reductions in gestational age-specific neonatal mortality, probably related to high-risk obstetric and neonatal care. Technological developments in these areas may have differentially benefited Whites, resulting in an increasing racial disparity in neonatal mortality rates. Preterm African-American infants no longer have a marked survival advantage over White infants, even at the gestational age limit of viability.     

胃液表皮生长因子与β-防御素在早产儿胃肠功能障碍中作用的临床研究

目的:研究不同胎龄早产儿及发生胃肠功能障碍后胃液中表皮生长因子及β-防御素的水平变化,探讨二者在胃肠功能障碍的病理生理过程中的作用,为寻找早期预测早产儿胃肠功能的客观指标提供理论依据。方法:齐鲁儿童医院新生儿监护室2006年1月～2010年6月160例不同胎龄早产儿,分为观察组(胃肠功能障碍组)及对照组(无胃肠功能障碍组),两组按28～30周、30+1～32周、32+1～34周、34+1～36+6周胎龄分4组,采用ELISA方法检测胃液中表皮生长因子及β-防御素水平变化。胃肠功能障碍组收集样本时间为症状出现3 h内,对照组为入院3 h内,均为空腹胃液。结果:①表皮生长因子(ng/L)观察组中不同胎龄的4组分别为68.2±11.4、172.0±34.4、284.8±30.6、444.4±82.4,对照组为343.0±45.2、494.4±29.4、703.3±118.1、947.8±158.1,P值均<0.05,差异有统计学意义;②β-防御素(ng/L)观察组不同胎龄的4组分别为66.5±14.7、158.6±34.4、233.7±41.9、391.2±28.8;对照组为298.4±33.4、401.2±40.8、622.8±68.5、787.6±61.6,P值均<0.05,差异有统计学意义。结论:①早产儿胃肠功能障碍时表皮生长因子及β-防御素的分泌水平明显降低,提示二者分泌水平的变化,可以反映胃肠道功能的损害程度;②胃肠道表皮生长因子与β-防御素的分泌水平与胎龄成正相关,提示两者在胃肠道的发育和成熟过程中起重要作用;③各胎龄组表皮生长因子与β-防御素的分泌水平呈正相关关系。