Respiratory outcome in preterm small for gestational age fetuses with or without abnormal umbilical artery Doppler and/or maternal hypertension.

OBJECTIVE: To study respiratory outcome in preterm small for gestational age (SGA) fetuses with or without signs of intrauterine growth restriction due to placental insufficiency, and with or without maternal hypertension. METHODS: This was a retrospective study of 187 neonates with birth weight <10(th) percentile and gestational age <34 weeks. Results from umbilical artery Doppler velocimetry were used to identify the abnormal Doppler subgroup. RESULTS: No significant difference in respiratory outcome between SGA fetuses with normal (SGA-N) or abnormal (SGA-A) umbilical artery Doppler examination was found. Within the SGA-A group, the respiratory distress syndrome (RDS) incidence (OR 5.6, 95% CI 1.7-18.3), RDS grade (OR 6.7, 95% CI 1.2-38.5), and need for surfactant (OR 5.3, 95% CI 1.1-24.4) were higher in infants of women with hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome as compared to those of normotensive mothers. CONCLUSIONS: Lung maturation is not accelerated with placental insufficiency. SGA-A fetuses of mothers with HELLP syndrome have a significantly poorer respiratory outcome than those with healthy mothers. Possibly, fetuses of mothers with HELLP syndrome are subjected to 'oxidative stress' causing lung damage rather than lung maturation.     

The Effects of Prenatal Secondhand Smoke Exposure on Preterm Birth and Neonatal Outcomes

ObjectiveTo examine the relationship between prenatal secondhand smoke (SHS) exposure, preterm birth and immediate neonatal outcomes by measuring maternal hair nicotine.DesignCross‐sectional, observational design.SettingA metropolitan Kentucky birthing center.ParticipantsTwo hundred and ten (210) mother–baby coupletsMethodsNicotine in maternal hair was used as the biomarker for prenatal SHS exposure collected within 48 hours of birth. Smoking status was confirmed by urine cotinine analysis.ResultsSmoking status (nonsmoking, passive smoking, and smoking) strongly correlated with low, medium, and high hair nicotine tertiles (ρ=.74; p<.001). Women exposed to prenatal SHS were more at risk for preterm birth (odds ratio [OR]=2.3; 95% Confidence Interval [CI] [.96, 5.96]), and their infants were more likely to have immediate newborn complications (OR=2.4; 95% CI [1.09, 5.33]) than nonexposed women. Infants of passive smoking mothers were at increased risk for respiratory distress syndrome (RDS) (OR=4.9; 95% CI [1.45, 10.5]) and admission to a Neonatal Intensive Care Unit (NICU) (OR=6.5; CI [1.29, 9.7]) when compared to infants of smoking mothers (OR=3.9; 95% CI [1.61, 14.9]; OR=3.5; 95% CI [2.09, 20.4], respectively). Passive smokers and/or women with hair nicotine levels greater than .35 ng/ml were more likely to deliver earlier (1 week), give birth to infants weighing less (decrease of 200‐300 g), and deliver shorter infants (decrease of 1.1‐1.7 cm).ConclusionsPrenatal SHS exposure places women at greater risk for preterm birth, and their newborns are more likely to have RDS, NICU admissions, and immediate newborn complications.     

Respiratory outcome in preterm small for gestational age fetuses with or without abnormal umbilical artery Doppler and/or maternal hypertension

Objective.?To study respiratory outcome in preterm small for gestational age (SGA) fetuses with or without signs of intrauterine growth restriction due to placental insufficiency, and with or without maternal hypertension.

Methods.?This was a retrospective study of 187 neonates with birth weight <10^th percentile and gestational age <34 weeks. Results from umbilical artery Doppler velocimetry were used to identify the abnormal Doppler subgroup.

Results.?No significant difference in respiratory outcome between SGA fetuses with normal (SGA-N) or abnormal (SGA-A) umbilical artery Doppler examination was found. Within the SGA-A group, the respiratory distress syndrome (RDS) incidence (OR 5.6, 95% CI 1.7–18.3), RDS grade (OR 6.7, 95% CI 1.2–38.5), and need for surfactant (OR 5.3, 95% CI 1.1–24.4) were higher in infants of women with hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome as compared to those of normotensive mothers.

Conclusions.?Lung maturation is not accelerated with placental insufficiency. SGA-A fetuses of mothers with HELLP syndrome have a significantly poorer respiratory outcome than those with healthy mothers. Possibly, fetuses of mothers with HELLP syndrome are subjected to ‘oxidative stress’ causing lung damage rather than lung maturation.     

Advanced maternal age and fetal growth inhibition in triplets

OBJECTIVE: To determine whether advanced maternal age is associated withfetal growth inhibition in triplets. STUDY DESIGN: We conducted a retrospective cohort study on triplet live births in the United States from 1995 through 1998. The outcomes of fetal growth inhibition measured were low birth weight, very low birth weight, preterm birth, very preterm birth and smallnessfor gestational age. We generated adjusted ORs after taking into account intracluster correlations using the generalized estimating equation framework. RESULTS: As compared to women of younger maternal age (20-29), mature (30-39) and older women (> or =40 years) with triplet gestations tended to have a lower likelihood offetal growth inhibition. Mean birth weight and mean gestational age at delivery increased with increasing maternal age in a dose-dependent pattern (p for trend < 0.0001). As compared to triplets born to younger mothers, those of older women were less likely to have low birth weight (OR=0.51, 95% CI=0.37-0.69) or very low birth weight (OR = 0.58, 95% CI = 0.47-0.72) or to be preterm (OR = 0.39, 95% CI = 0.27-0.56) or very preterm (OR = 0.67, 95% CI = 0.55-0.80). The riskfor small-for-gestational-age infants was comparable. CONCLUSION: Older maternal age is associated with morefavorable triplet fetal growth parameters, although the exact mechanisms of this paradox remain poorly understood.     

Intrauterine smoke exposure: a new risk factor for bronchopulmonary dysplasia?

OBJECTIVE: To evaluate the role of intrauterine smoke exposure and other variables on the development of bronchopulmonary dysplasia (BPD) in infants with birth weight < 1500 g (VLBW). METHODS: This case-control study investigated 277 VLBW infants (141 cases, 136 controls) admitted at birth to neonatal intensive care unit and survived to discharge. A retrospective telephone interview provided detailed parental information supplementing clinical data. Logistic regression assessed the effects of birth weight < 1000 g, gestational age < 30 weeks (GA<30), respiratory distress syndrome (RDS), neonatal mechanical ventilation > 7 days (MV>7), patent ductus arteriosus (PDA), intrauterine smoke exposure > or = 3 months (ISE), and of parental history of asthma on BPD (oxygen dependency at 28 days with characteristic radiographic abnormalities) occurrence. RESULTS: Including all variables, only GA<30, RDS and MV>7 were significantly associated with BPD. ISE did not contribute significantly to this model (odds ratio [OR] 1.94; 95% confidence interval 0.88-4.26). Excluding iatrogenic variable MV>7, GA<30, RDS, PDA and ISE (OR 2.21; 95% confidence interval 1.03-4.76) were significantly associated with BPD. Analyzing GA as a continuous variable, the OR was 0.63 for each additional week. CONCLUSIONS: Prolonged mechanical ventilation, RDS and low gestational age were the major BPD determinants. Intrauterine smoke exposure seems to influence independently BPD development.     

产前多疗程与单疗程肾上腺糖皮质激素治疗对早产儿影响的Meta 分析

目的 综合评价产前多疗程与产前单疗程肾上腺糖皮质激素治疗对早产儿的有效性和安全性。方法 对满足条件的7篇有关产前肾上腺糖皮质激素治疗对早产儿影响的队列研究进行Meta分析。结果 产前多疗程肾上腺糖皮质激素治疗可降低早产儿动脉导管未闭(PDA)的发病率(OR=0．51，95％CI0．49～0．54)，有使早产儿呼吸窘迫综合征(RDS)发生率降低的趋势(OR=0．72，95％CI0．49～1．07)。但可增加早产儿败血症的发生率(OR=1．62，95％CI1．07～2．44)，且不能降低早产儿颅内出血(ICH)(OR=0．65，95％CI0．37～1．15)、坏死性小肠结肠炎(NEC)(OR=1．30，95％CI0．79～2．12)和慢性肺疾病(CLD)(OR=0．94，95％CI0.59～1．49)的发生率及病死率(OR=1．07，95％CI0．42～2．75)，也不能使早产儿出生后肺表面活性物质(PS)的应用减少(OR=0．86，95％CI0．48～1．55)。结论 无法根据现有的Meta分析结果证明产前多疗程肾上腺糖皮质激素治疗比产前单疗程肾上腺糖皮质激素治疗更有效和危险性更小。     

Parity effect on preterm birth and growth outcomes among infants with isolated omphalocele

OBJECTIVE: To assess the association between parity and fetal morbidity outcomes among omphalocele-affected fetuses. STUDY DESIGN: We carried out a retrospective study of 498 cases of isolated omphalocele (210 born to nulliparous and 288 to multiparous mothers) in New York State from 1983 through 1999. Infants of nulliparous mothers were compared to those of multiparous gravidas using adjusted odds ratios generated from a logistic regression. RESULTS: Omphalocele-affected fetuses of nulliparous mothers had a lower risk of being delivered preterm (odds ratio (OR)=0.49; 95% CI=0.27-0.90) but comparable risks for low birth weight (OR=1.01; 95% CI=0.60-1.72), very low birth weight (OR=0.33; 95% CI=0.09-1.20), very preterm birth (OR=0.42; 95% CI=0.15-1.16), and small size for gestational age (SGA) [OR=0.61; 95% CI=0.23-1.63]. CONCLUSION: Omphalocele-affected fetuses of multiparous mothers have double the risk for preterm birth compared to their nulliparous counterparts. This information is potentially useful in counseling parents whose fetuses have omphaloceles.     

Caesarean before labour between 34 and 37 weeks: What are the risk factors of severe neonatal respiratory distress?

OBJECTIVE: To assess the frequency of severe neonatal respiratory distress and identify its risk factors in caesarean deliveries before labour between 34 and 37 weeks' gestation. STUDY DESIGN: Retrospective study of children born by caesarean delivery before labour between 34 and 37 weeks, between 1999 and 2003 in a level 3 maternity unit. The frequencies of severe and mild neonatal respiratory distress were calculated. Univariate and multivariate analyses studied the factors potentially associated with severe respiratory distress: gestational age, type of pregnancy (singleton or multiple), condition of membranes, maternal diabetes, indication for caesarean, antenatal corticosteroid therapy, intrauterine growth retardation, infant's sex and birth weight. RESULTS: The 189 study subjects included 107 singletons and 82 twins: 28% required intensive care for severe respiratory distress and 30.2% developed mild respiratory distress. Gestational age was a significant risk factor (p = 0.01), especially before 36 weeks (adjusted OR = 2.1; 95% CI: 1.0-4.4). The multivariate analysis indicated that singleton pregnancies (adjusted OR = 3.2; 95% CI: 1.5-6.7) and caesareans for fetal indications (adjusted OR = 2.7; 95% CI: 1.2-5.7) are also risk factors and that premature rupture of the membranes is a "protective" factor against respiratory complications (adjusted OR = 0.2; 95% CI: 0.1-0.8). CONCLUSION: More than a quarter of the infants delivered by caesarean before labour between 34 and 37 weeks' gestation in our level 3 maternity unit had severe respiratory distress. Although our population may not be typical of the general population, this finding and the risk factors associated with it should be taken into account in determining the best time and place for delivery of each patient.     

Pregnancy, delivery, and neonatal complications after treatment with antiepileptic drugs

AIM: To study the risk for complications during pregnancy, delivery, and neonatal period after the use of antiepileptic drugs (AEDs) during pregnancy. METHODS: Women treated with AEDs during pregnancy and with singleton deliveries were identified from the Swedish Medical Birth Registry during the period July 1 1995 to and including 2001 (n = 1350). Risk estimates were made using the Mantel-Haenszel procedure and comparisons with all singleton births in Sweden during this period (n = 559,491). Stratification was made for year of birth, maternal age, parity, and smoking habits. RESULTS: Most of the women (n = 1207, 89%) used AEDs in monotherapy. Carbamazepine was the most commonly used drug (n = 683), followed by valproic acid (n = 255). The rate of caesarean sections was significantly increased (OR = 1.64, 95% CI 1.43-1.89), but it was not possible to differentiate between elective and emergency sections. The risk for pre-eclampsia (OR = 1.66, 95% CI 1.32-2.08) and for hemorrhage after vaginal delivery was increased (OR = 1.29, 95% CI 1.02-1.63). The neonates showed an increased risk for respiratory distress (OR = 2.06, 95% CI 1.62-2.63). CONCLUSION: The study demonstrates a slightly increased risk only for preeclampsia, vaginal hemorrhage after delivery, and respiratory distress in the newborn after the use of AEDs during pregnancy.     

Maternal smoking and infant respiratory distress syndrome

The relationship between maternal smoking and infant respiratory distress syndrome (RDS) was investigated among 550 premature (36 weeks or less) births delivered at the University of Washington Hospital from 1977 to 1980. Forty-five percent of the mothers were smokers. To avoid bias due to the reduced birth weight of infants of smokers, infants of smokers and nonsmokers were compared within small gestational age categories (two-week intervals) and not by birth weight categories. Infants of mothers who smoked had a reduced incidence of RDS for their gestation compared with infants of nonsmokers. The probability of RDS (adjusted for gestational age and method of delivery) was 25% for the infants of smokers versus 38% for the infants of nonsmokers (odds ratio = 0.55, P = .005), equivalent to approximately a 1.5-week acceleration in lung maturity for infants of smokers. The smoking effect was not explained by demographic differences between smokers and nonsmokers, nor by differences in the incidence of pregnancy complications between the two groups. This study adds support to the theory that adverse pregnancy conditions may lead to an acceleration in pulmonary maturity to allow earlier extrauterine adaptation.     

Cigarette smoking and pre-eclampsia: their association and effects on clinical outcomes

Objective : To determine the effects of smoking on pre-eclampsia in an inner-city, predominantly African-American prenatal population. Methods : We performed a retrospective cohort study of all primigravidas who delivered singletons in our institution between 1980 and 1989. The study population consisted of 1862 smokers and 16 508 non-smokers. Univariate analysis and multiple logistic regression were used to identify relationships between smoking and adverse outcomes. Results : The pre-eclampsia rate was significantly lower among smokers (11.3% vs. 13.0%, OR 0.85, 95% CI 0.73-0.99). Smokers with pre-eclampsia had higher rates of infants with low birth weight (OR 1.44, 95% CI 1.26-1.65) and very low birth weight (OR 1.85, 95% CI 1.55-2.20) and higher rates of placental abruption (OR 3.49, 95% CI 1.65-7.28) compared to non-smoking pre-eclamptics. This relationship persisted after correction for age, race, chronic hypertension and pre-eclampsia as confounding variables. Conclusions : Cigarette smoking was associated with a lower rate of pre-eclampsia among primigravidas independently of other maternal factors. Perinatal outcomes were significantly worsened among pre-eclamptics who smoked.     

Respiratory distress syndrome and maternal birth weight effects

OBJECTIVE: To study traditional risk factors and the intergenerational risk factor maternal low birth weight (LBW) for respiratory distress syndrome (RDS) in infants in multiple ethnic groups. METHODS: The population-based database consists of hospital records linked to Washington state maternal and infant vital records. Four racial-ethnic groups were studied, whites, blacks, Native Americans, and Hispanics. Poisson regression models were used to estimate relative risks of various factors for RDS. RESULTS: Rates for RDS were whites 1.2%, blacks 1.9%, Native Americans 1.3%, and Hispanics 1.0%. Maternal LBW was associated with increased relative risk (RR) for RDS in whites (2.6, 95% confidence interval [CI] 1.6, 4.2) and blacks (3.3, 95% CI 1.9, 5.6) for infants born vaginally. Compared with mothers of normal infants, birth weights of mothers of infants with RDS and delivered vaginally were significantly lower in whites, blacks, and Native Americans. The association of maternal LBW with RDS persisted in blacks even when multiple risk factors were added to the model (RR 2.4; 95% CI 1.1, 5.1). CONCLUSION: The association of maternal LBW with RDS is probably due in part to the association of maternal LBW with infant LBW and preterm birth. The strong persistent association of maternal LBW with RDS in blacks suggests that improvement of perinatal outcomes in that group will require improvement of long-term birth weight distribution.     

Cigarette smoking and pre-eclampsia: their association and effects on clinical outcomes.

OBJECTIVE: To determine the effects of smoking on pre-eclampsia in an inner-city, predominantly African-American prenatal population. METHODS: We performed a retrospective cohort study of all primigravidas who delivered singletons in our institution between 1980 and 1989. The study population consisted of 1862 smokers and 16,508 non-smokers. Univariate analysis and multiple logistic regression were used to identify relationships between smoking and adverse outcomes. RESULTS: The pre-eclampsia rate was significantly lower among smokers (11.3% vs. 13.0%, OR 0.85, 95% CI 0.73-0.99). Smokers with pre-eclampsia had higher rates of infants with low birth weight (OR 1.44, 95% CI 1.26-1.65) and very low birth weight (OR 1.85, 95% Cl 1.55-2.20) and higher rates of placental abruption (OR 3.49, 95% CI 1.65-7.28) compared to non-smoking pre-eclamptics. This relationship persisted after correction for age, race, chronic hypertension and pre-eclampsia as confounding variables. CONCLUSIONS: Cigarette smoking was associated with a lower rate of pre-eclampsia among primigravidas independently of other maternal factors. Perinatal outcomes were significantly worsened among pre-eclamptics who smoked.     

Contribution of elective delivery to severe respiratory distress at term

We sought to determine the contribution of elective delivery to severe respiratory distress syndrome (RDS) on a weekly basis from 37-40 weeks' gestation. Chart reviews confirmed gestational age, delivery reason, and primary diagnosis of all inborn neonates with RDS requiring mechanical ventilation delivered at 37 0/7-40 6/7 weeks' gestation from 1/1/90-12/31/99. Exclusion criteria were sepsis, pneumonia, meconium aspiration, asphyxia, pulmonary hemorrhage, hydrops, chromosomal abnormality, or congenital malformations affecting respiration. Thirty-five thousand and thirty-one deliveries occurred from 37 0/7-40 6/7 weeks; 18 (0.05%) had RDS requiring mechanical ventilation. Nine infants delivered at 37 0/7-37 6/7 weeks, (OR for RDS = 38.5; 95% CI = 8.3, 178.3), seven delivered at 38 0/7-38 6/7 weeks, (OR for RDS = 13.3; 95% CI = 2.8, 64.0), and two delivered at 39 0/7-40 6/7 weeks. Six of 18 infants were electively delivered without documented lung maturity. Infants born at 37 0/7-38 6/7 weeks are at significantly increased risk for severe RDS. One third of RDS cases were potentially avoidable.     

Risk factors for intrapair birth weight discordance in twins

Objectives: To determine the risk factors for birth weight discordance in twins. Methods: We used the United States (1995-97) Matched Multiple Birth File (n = 294 568) to assess the association between birth weight discordance and maternal sociodemographic, pregnancy and infant characteristics. Results: Eighty-four per cent of the twins were 0-19% discordant, 11.1% were 20-29% discordant, 3.4% were 30-39% discordant, and 1.8% were ≥ 40% discordant. The risk factors for birth weight discordance for same-sex twins were eclampsia (odds ratio (OR) 1.39, 95% confidence interval (CI) 1.20, 1.61), pre-eclampsia (OR 1.31, 95% CI 1.24, 1.38), pre-existing hypertension (OR 1.32, 95% CI 1.12, 1.56), diabetes (OR 1.13, 95% CI 1.04, 1.24) and certain congenital anomalies. For opposite-sex twins, the risk factors for birth weight discordance were pre-eclampsia (OR 1.17, 95% CI 1.09, 1.27), pre-existing hypertension (OR 1.59, 95% CI 1.32, 1.91), and certain congenital anomalies. Also, smoking and increased maternal age were associated with birth weight discordance in both same-sex and opposite-sex twins. Conclusions: Maternal hypertensive disorders, smoking and delayed childbearing were associated with intrapair birth weight discordance. The mechanisms of these associations deserve further investigation.     

Elective cesarean delivery, neonatal intensive care unit admission, and neonatal respiratory distress

OBJECTIVE: To evaluate the relationship among gestational age at elective cesarean delivery, neonatal intensive care unit (NICU) admission, and whether the presence of pre-cesarean delivery labor or ruptured membranes affected the incidence of neonatal respiratory distress. METHODS: A chart review was performed of all elective caesarean deliveries (documented planned in advance) during 1 year, 2004-2005, in the Calgary Health Region; resulting in liveborn infants at or after 36 weeks of gestation and birth weight equal to or greater than 2,500 g. The primary outcomes are relative risk of NICU admission or respiratory distress. RESULTS: A total of 1,193 paired maternal and infant charts were reviewed. Admission rate to the NICU was 156 of 1,195 (13.1%). The most common admitting diagnosis was respiratory distress, 126 of 156 (80%). Male gender was a significant risk factor for admission to the NICU or respiratory distress (odds ratio [OR] 1.82, 95% confidence interval [CI] 1.27-2.60, and OR 1.98, 95% CI 1.33-2.95, respectively). Elective cesarean delivery beyond 270 days of gestational age (38(4/7) weeks) significantly reduced the risk for NICU admission or respiratory distress (OR 0.62, 95% CI 0.43-0.89, and OR 0.50, 95% CI 0.34-0.74, respectively). The presence of spontaneous contractions or rupture of membranes before elective cesarean delivery did not reduce the risk of NICU admission or respiratory distress (OR 1.05, 95% CI 0.69-1.62, and OR 0.96, 95% CI 0.60-1.55, respectively). CONCLUSION: Admission to NICU and development of respiratory distress were associated with gestational age at time of elective cesarean delivery and male gender. Awaiting the onset of labor or ruptured membranes did not appear to reduce the risk of NICU admission or neonatal respiratory distress.     

Risk of preterm delivery in relation to maternal low birth weight

OBJECTIVE: We examined the relationship between maternal low birth weight and preterm delivery risk. METHODS: Information concerning maternal birth weight was collected during in-person interviews. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). Preterm delivery cases were studied in aggregate, in subgroups (spontaneous preterm labor, preterm premature rupture of membranes, medically induced preterm delivery, moderate preterm delivery [gestational age at delivery 34-36 weeks], and early preterm delivery [gestational age at delivery<34 weeks]). RESULTS: After adjusting for confounders, women weighing<2,500 g at birth had a 1.54-fold increased risk of preterm delivery versus women weighing=2,500 g (95% CI 0.97-2.44). Maternal low birth weight was associated with a 2-fold increased risk of spontaneous preterm delivery (95% CI 1.03-3.89), but weakly associated with preterm premature rupture of membranes (OR=1.44; 95% CI 0.67-3.09) and medically induced preterm delivery (OR=1.10; 95% CI 0.43-2.82). Maternal low birth weight was more strongly associated with early preterm delivery (OR=1.94) than with moderate preterm delivery (OR=1.46). Women weighing<2,500 g at birth and who became obese (pre-pregnancy body mass index, =30 kg/m2) before pregnancy had a 3.65-fold increased risk of preterm delivery (95% CI 1.33-10.02) versus women weighing=2,500 g at birth and who were not obese prior to pregnancy (<30 kg/m2). CONCLUSIONS: Results confirm earlier findings linking maternal low birth weight with future risk of preterm delivery.     

Transient hypothyroxinemia of prematurity and histological chorioamnionitis

BACKGROUND: Transient hypothyroxinaemia of prematurity (THOP) is a common condition of preterm infants whose causes remain unclear. We tested the hypothesis that THOP is associated with histological chorioamnionitis (HCA). METHODS: Whole blood T4 and TSH concentrations on day 4 and at 40 weeks' postmenstrual age (rtx-T4 and rtx-TSH), placental histology and illness severity were prospectively evaluated in 155 very low birth weight (VLBW) infants. RESULTS: HCA-positive infants showed significantly decreased blood total T4 concentrations on day 4, as compared to the HCA-negative population (P<0.0001), along with comparable TSH, rtx-T4, and rtx-TSH blood concentrations. None of the infants showed evidence of hypothyroidism during the study. A total T4 < or = 4.4 microg/dL on postnatal day 4 identified HCA-positive newborns with 90.8%, sensitivity, 94.7%, specificity, 96.7% positive predictive and 85.7% negative predictive values. HCA (OR: 32.19; 95% CI: 8.95-115.64), birth weight < or = 880 g (OR: 4.1; 1.15-14.64), and RDS (OR: 3.71, 95% CI: 1.13-12.25) were independently associated with evidence of hypothyroxinaemia on day 4. CONCLUSION: Our findings indicate a previously un-recognized relationship between HCA and THOP, hence suggesting a predominant role for a fetal systemic inflammatory response syndrome in the pathogenesis of THOP.     

Timing of planned cesarean delivery by racial group

OBJECTIVE: To estimate the incidence of newborn respiratory distress syndrome (RDS) and transient tachypnea of the newborn (TTN) in relation to gestational age and planned cesarean delivery in white, South Asian, and black women. METHODS: Included in this study were 442,596 white, South Asian, and black women who delivered single live infants at 28 of weeks gestation onwards between 1988 and 2000. Using multiple logistic regression, the gestation-specific patterns of RDS for all deliveries and RDS plus TTN for deliveries by planned cesarean delivery were analyzed by racial group. The predictors of RDS from 37 weeks of gestation onwards were determined. RESULTS: More South Asians (28.2%, 95% confidence interval [CI] 27.8-28.6) and blacks (24.6%, 95% CI 24.0-25.1) delivered spontaneously before 39 weeks than whites (16.9%, 95% CI 16.8-17.1). Respiratory distress syndrome patterns by gestation differed significantly (P<.001). Compared with whites, the gestation-specific crude RDS rate was lower in South Asians up until 40 weeks and after adjusting for confounders; South Asians were most protected against RDS (odds ratio [OR] 0.6, 95% CI 0.5-0.9). The gestation-specific patterns of RDS plus TTN after planned cesarean delivery also differed significantly (P<.001) between racial groups. The lowest rate of TTN plus RDS was at 40 weeks for whites, but in South Asians and blacks, it was lowest at 38 weeks. CONCLUSION: The gestation-specific patterns of RDS differed significantly by racial group from 32 weeks of gestation onwards. Preterm black infants had a lower rate of RDS when compared with whites; also, South Asians had the lowest rate of transient tachypnea until 38 weeks and the lowest rate of RDS until 40 weeks of gestation. The advantages of waiting until 39 weeks to perform planned cesarean delivery for white women are not seen in South Asians or blacks.