Background At any given gestational age, infants with low birthweight have relatively high morbidity and mortality. It is notknown, however, whether there is a threshold weight below whichmorbidity and mortality are significantly greater, or whetherthat threshold varies with gestational age.
Methods We analyzed the neonatal outcomes of death, five-minuteApgar score, umbilical-artery blood pH, and morbidity due toprematurity for all singleton infants delivered at ParklandHospital, Dallas, between January 1, 1988, and August 31, 1996.A distribution of birth weights according to week of gestationat birth was created. Infants in the 26th through 75th percentilesfor weight served as the reference group. Data on preterm infants(those born at 24 to 36 weeks of gestation) were analyzed separatelyfrom data on infants delivered at term (37 or more weeks ofgestation).
Results A total of 122,754 women and adolescents delivered singletonlive infants without malformations between 24 and 43 weeks ofgestation. Among the 12,317 preterm infants who were analyzed,there was no specific birth-weight percentile at which morbidityand mortality increased. Among 82,361 infants who were bornat term and whose birth weights were at or below the 75th percentile,however, the rate of neonatal death increased from 0.03 percentin the reference group (26th through 75th percentile for weight)to 0.3 percent for those with birth weights at or below the3rd percentile (P<0.001). The incidence of five-minute Apgarscores of 3 or less and umbilical-artery blood pH values of7.0 or less was approximately doubled for infants at or belowthe 3rd birth-weight percentile (P=0.003 and P<0.001, respectively).The incidence of intubation at birth, seizures during the firstday of life, and sepsis was also significantly increased amongterm infants with birth weights at or below the 3rd percentile.These differences persisted after adjustment for the mother'srace and parity and the infant's sex.
Conclusions Mortality and morbidity are increased among infantsborn at term whose birth weights are at or below the 3rd percentilefor their gestational age.
Each year in the United States, approximately 250,000 infantsare born weighing less than 2500 g. These infants are classifiedas having low birth weight.1 Although the majority of theseinfants are born before term, approximately 40,000 are bornat term according to National Institutes of Health estimates,having suffered intrauterine growth retardation.2
In 1963 Lubchenco and coworkers3 published detailed birth-weightnomograms according to gestational week. Small-for-gestational-ageinfants were subsequently defined as those whose weights werebelow the 10th percentile for their gestational ages.4 Theseinfants were found to be at increased risk for neonatal death.For example, the neonatal mortality rate for small-for-gestational-ageinfants born at 38 weeks of gestation was 1 percent, as comparedwith 0.2 percent for those with appropriate birth weights. Notall infants with birth weights below the 10th percentile havepathologic growth retardation, however; some are small simplybecause of maternal constitutional factors.5,6
Although the concept of abnormal fetal growth is basic to modernideas of perinatal medicine, there is limited information concerningthe birth-weight threshold for a given gestational age at whichmorbidity and mortality increase significantly. For examplesome advocate the use of the 10th percentile as such a thresholdvalue,4 whereas others recommend the 5th,7 3rd,8 or 15th9 percentile.We undertook this study to determine the birth-weight thresholds,for both preterm and term infants, associated with a significantincrease in adverse neonatal outcomes. The birth-weight distributionused was specific to the study population. Between 1988 and1996, approximately 127,000 infants were delivered at our hospital.The availability of data from this cohort permitted us to derivea population-based birth-weight nomogram and then to assessthe birth-weight thresholds at which the well-being of newborninfants might be compromised.
Methods
Study Population
Selected obstetrical and neonatal outcomes for all women deliveringinfants at Parkland Hospital in Dallas are routinely enteredinto a computerized data base. Nurses attending each deliverycomplete an obstetrical data sheet, and research nurses assessthe data for consistency and completeness before electronicstorage. Data on infants' outcomes are abstracted from dischargerecords. Parkland Hospital is a tax-supported institution servingDallas County. The obstetrics service is staffed by house officersand faculty members of the Department of Obstetrics and Gynecologyat the University of Texas Southwestern Medical School.
Between January 1, 1988, and August 31, 1996, a total of 126,680women and adolescents delivered infants at the hospital, ofwhom 122,754 were live-born singleton infants without malformationsand with gestational ages of 24 weeks or more. Infants deliveredat less than 24 weeks of gestational age were excluded fromour study because their intrapartum management was influencedby concern about viability. Stillbirths were excluded becausethe gestational age at which fetal growth ceased could not beprecisely determined, since delivery, and thus measurement ofbirth weight, often occurred days to weeks after fetal death.Ninety-seven percent of the mothers received prenatal care,averaging eight visits, in our hospital system. Approximately60 percent were enrolled for prenatal care in the first trimester,and 90 percent enrolled before the end of the second trimester.
Gestational Age
For the purpose of this study, the obstetrical estimate of gestationalage that was used to manage the care of the women and adolescentsduring the intrapartum period was also used to create a distributionof birth weights for each gestational week. This estimate wasbased on the date of the last menstrual period and the resultsof obstetrical ultrasonography, if any, performed during thepregnancy. The reported time of the last menstrual period wasaccepted as correct if the fundal height measured between 18and 30 weeks of gestation was correlated with the week of gestationwithin 2 cm.10 Subjects with discrepancies between the two valuesunderwent obstetrical ultrasonography.
The validity of the obstetrical estimate of gestational agebased on the menstrual history was assessed by two separatemethods. First, a cohort of 34,475 women and adolescents whounderwent antepartum ultrasonography was identified. These subjectsdid not differ significantly from the total study populationwith regard to age, race, or parity. The correlation coefficientfor the estimate of gestational age based on ultrasonographyand the obstetrical estimate of gestational age based on thelast menstrual period was 0.9. The mean (±SD) gestationalage at the time of ultrasonography was 25±7 weeks. Similarly,the correlation coefficient for the obstetrical estimate ofgestational age and the pediatrician's assessment of the gestationalage of the newborn infant was 0.7. In 108,493 women (88 percent),the obstetrical estimate and the pediatrician's estimate werewithin two weeks of each other. (The obstetrical estimates ofgestational age were available to the pediatricians.)
Birth Weight
The distributions of birth weights for each completed week ofgestation were examined for statistical normality, and smoothedbirth-weight curves were derived for each percentile.11 Forexample, 38 completed weeks of gestation included 38 weeks,0 days, through 38 weeks, 6 days. Six categories of birth-weightpercentile were selected for study: the 3rd or below, 4th through5th, 6th through 10th, 11th through 15th, 16th through 25th,and 26th through 75th percentiles. Infants whose birth weightsfell in the 26th through 75th percentiles were used as the referencegroup.
Outcome Measures
The outcomes we studied included death up to 28 days of age,an Apgar score of 3 or less at five minutes, and an umbilical-arteryblood pH of 7.0 or less. The latter two measurements assessedcharacteristics attributable to the condition of the infantat birth. Umbilical-cord blood was obtained from all infantsfor measurement of pH. In infants born at term, morbidity wasdefined as the onset of seizures in the first 24 hours afterbirth or the need for intubation in the delivery room. In preterminfants, morbidity was defined as respiratory distress (theneed for ventilator therapy in the first 24 hours after birth);intraventricular hemorrhage, grade 3 or 4; necrotizing enterocolitisrequiring surgery; or sepsis. The diagnosis of sepsis requireda positive blood culture.
Statistical Analysis
Smoothed curves for birth-weight percentiles according to gestationalage were derived for the entire cohort. Similar curves werealso constructed according to the mother's race and parity andthe infant's sex. Univariate analysis of infants' outcomes accordingto birth-weight percentile was performed with use of chi-squarestatistics. The estimates and significance levels were adjustedfor the mother's race and parity and the infant's sex by theCochran–Mantel–Haenszel method. Bonferroni correctionswere used in cases of multiple testing. All P values are two-sided.
Results
Of the women and adolescents whose pregnancy outcomes are describedin this report, 54 percent (65,712) were Hispanic, 28 percent(34,872) were black, 15 percent (18,616) were white, and 3 percent(3554) were of other racial or ethnic backgrounds. The meanmaternal age was 24±6 years; 3 percent were under theage of 16 years and 4 percent were 35 years old or older. Atotal of 45,937 (37 percent) were nulliparous.
Data on 122,754 singleton infants without malformations (12,317preterm infants and 110,437 term infants) were available foranalysis. Of these, 91,580 infants (9219 preterm infants and82,361 term infants) had birth weights at or below the 75thpercentile. The infants' outcomes, according to birth-weightpercentile, were analyzed separately for those delivered at36 weeks or less of gestation (preterm birth) and those deliveredat 37 weeks or more (birth at term).
Preterm Infants
Selected outcomes for the 9219 preterm infants with birth weightsat or below the 75th percentile are shown according to birth-weightcategory in Table 1. The presence or absence of severe fetalacidemia (umbilical-artery blood pH, 7.0 or less), necrotizingenterocolitis, and sepsis was not related to birth-weight category.The incidence of grade 3 or 4 intraventricular hemorrhage, however,was significantly increased among preterm infants in the smallestbirth-weight category. Grade 3 or 4 intraventricular hemorrhagewas diagnosed in 3.2 percent of infants at or below the 3rdpercentile for birth weight, as compared with 1.5 percent inthe reference group of infants in the 26th through 75th percentiles(P= 0.01). The incidence of respiratory distress requiring ventilatortherapy was significantly increased among infants in each ofthe birth-weight percentiles below the 26th percentile, as comparedwith the reference group (Table 1).
Table 1. Outcomes of Live-Born Singleton Preterm Infants (Born at 24 to 36 Weeks of Gestation) in Relation to Birth-Weight Percentile.
Because the incidence of respiratory distress was significantlyhigher in all the birth-weight percentiles below the 26th percentilethan in the reference group, we expanded the analysis to includeall possible birth-weight percentiles (Figure 1). The incidenceof respiratory distress increased as the birth-weight percentiledecreased. Analysis of the data after stratification accordingto gestational-age groups revealed an increasing incidence ofrespiratory distress associated with both lower gestationalage and lower birth-weight percentile (Figure 2). As we didwith respiratory distress, we expanded the analysis of neonataldeath to encompass all birth-weight percentiles (Figure 1).Neonatal death rates among preterm infants were proportionalto fetal weight across the entire spectrum of birth-weight percentiles.The birth-weight–percentile thresholds for a significantlyincreased risk of respiratory distress and neonatal death amongpreterm infants were also analyzed with adjustment for the mother'srace and parity and the infant's sex. No specific birth-weightthreshold was significantly associated with either of theseoutcomes.
Figure 1. Incidence of Respiratory Distress and Neonatal Death among 12,317 Preterm Infants (Born at 24 to 36 Weeks of Gestation), According to Birth-Weight Percentile.
Figure 2. Incidence of Respiratory Distress among 12,317 Preterm Infants, According to Birth-Weight Percentile after Stratification According to Gestational Age (28 through 30 Weeks, 31 or 32 Weeks, 33 or 34 Weeks, and 35 or 36 Weeks).
Term Infants
Selected outcomes for 82,361 term infants in relation to theirbirth-weight percentiles are shown in Table 2. The analysisexcluded 28,076 infants whose birth weights were above the 75thpercentile. The percentage of infants with low five-minute Apgarscores was significantly higher among those at or below the3rd birth-weight percentile (0.2 percent) than in the referencegroup (0.1 percent; P=0.003). Similarly, the incidence of severefetal acidemia and the need for intubation in the delivery roomwas significantly higher among the infants in this group (P<0.001for both outcomes). The incidence of seizures during the first24 hours of life, a potential reflection of intrapartum stress,was significantly increased in two of the lowest birth-weightgroups (those at or below the 3rd percentile, and those in the6th through the 10th percentiles). The rates of incidence ofsepsis and neonatal death were also significantly increasedamong infants at or below the 3rd percentile. In fact, the incidenceof neonatal death was almost 10 times as high among infantswith birth weights at or below the 3rd percentile as in thereference group (0.3 percent vs. 0.03 percent, P<0.001).
Table 2. Outcomes of Live-Born Singleton Term Infants (Born at 37 Weeks of Gestation) in Relation to Birth-Weight Percentile.
The data set was also analyzed with adjustment for the infant'ssex and the mother's race. The 3rd-percentile birth-weight thresholdfor increased morbidity and mortality (Table 2) remained significantwhen the data were analyzed according to these demographic factors.Similarly, parity did not significantly influence the birth-weightthresholds for adverse neonatal outcomes.
Discussion
The threshold birth-weight percentile for infant mortality andfor most indexes of morbidity that appears to define the boundarybetween normal and abnormal fetal growth is more readily apparentamong term infants than among preterm infants. Morbidity andmortality were significantly higher among term infants who wereat or below the 3rd percentile of weight for their gestationalage. In contrast, there was no specific birth-weight thresholdfor neonatal morbidity or mortality among preterm infants. Indeed,the risk of adverse outcomes, such as respiratory distress andneonatal death, increased continuously with decreasing birth-weightpercentiles among preterm infants.
There have been few reports describing birth-weight thresholdsfor adverse infant outcomes. The earliest such report4 linkedneonatal death to birth weight at the 10th percentile. For morethan 30 years, this percentile has been defined as the thresholdfor clinically important fetal growth restriction. Manning5also defined the 10th percentile as the threshold for elevatedneonatal morbidity and mortality, manifested as birth asphyxiaand abnormal neurologic development. However, all infants withbirth weights above the 10th percentile were considered to beof appropriate size for their gestational age. We chose to analyzeour results with birth weights at the 26th through 75th percentilesas the norm for fetal growth. Larger infants were excluded becausethey may have morbidity associated with excessive size. Manningdescribed a continuum of increasing risk for adverse infantoutcomes as birth weight decreased from the 10th to the 1stpercentile for gestational age. On the basis of an analysisof 8719 births, Kramer and colleagues12 also concluded thatmorbidity and mortality were continuously and inversely proportionalto fetal growth. Neonatal outcomes related to suboptimal fetalgrowth are associated with adverse neurologic outcomes at twoyears of age.13
There have been several reports of accelerated fetal pulmonarymaturation in association with intrauterine growth restriction,defined as a birth weight for gestational age that is belowthe 10th percentile. One explanation for this phenomenon isthat the fetus responds to a stressful environment by increasingadrenal glucocorticoid production, which leads to acceleratedfetal lung maturation.14 Although this concept pervades modernthinking about perinatal medicine, there is considerable controversyas to whether the growth-restricted infant truly has an advantagewith respect to the risk of respiratory distress. The resultsof our analysis of preterm infants, along with other recentreports,15 challenge this concept of accelerated maturation.We could not identify a specific fetal-growth threshold forrespiratory disease; instead, we found that the incidence ofrespiratory distress was inversely proportional to the birth-weightpercentile. However, respiratory distress was also significantlyassociated with gestational age among preterm infants. We thereforeanalyzed the incidence of respiratory distress at all birth-weightpercentiles in relation to gestational age; the incidence ofrespiratory disease was directly related to both the birth-weightpercentile and gestational age. In other words, morbidity amongpreterm infants is influenced by both fetal growth and fetalage. The same relations were not found among term infants, inwhom the effects of suboptimal fetal growth appear to be limitedto the most severely undergrown infants. The effects of suboptimalfetal growth persisted after adjustment for the mother's raceand parity and the infant's sex.
When is fetal growth suboptimal, or how small is too small?Our results suggest that for term infants, the answer is the3rd birth-weight percentile. For preterm infants, the effectsof suboptimal fetal growth are intensified by immaturity, makingit difficult to discern a fetal-growth threshold that clearlyidentifies growth-restricted infants who are at increased riskfor illness and death.
Source Information
From the Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas.
Address reprint requests to Dr. McIntire at the Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75235-9032, or at dmcint{at}mednet.swmed.edu.
References
Fetal growth restriction. In: Cunningham FG, MacDonald PC, Gant NF, et al. Williams obstetrics. 20th ed. Stamford, Conn.: Appleton & Lange, 1997:839-51.
National Institutes of Health. Diagnostic ultrasound imaging in pregnancy. Washington, D.C.: Government Printing Office, 1984. (NIH publication no. 84-667.)
Lubchenco LO, Hansman C, Dressler M, Boyd E. Intrauterine growth as estimated from liveborn birth-weight data at 24 to 42 weeks of gestation. Pediatrics 1963;32:793-800. [Free Full Text]
Battaglia FC, Lubchenco LO. A practical classification of newborn infants by weight and gestational age. J Pediatr 1967;71:159-163. [CrossRef][Medline]
Breart G, Rabarison Y, Plouin PF, Sureau C, Rumeau-Rouquette C. Risk of fetal growth retardation as a result of maternal hypertension: preparation to a trial on antihypertensive drugs. Dev Pharmacol Ther 1982;4:Suppl:116-123.
Usher R, McLean F. Intrauterine growth of live-born Caucasian infants at sea level: standards obtained from measurements in 7 dimensions of infants born between 25 and 44 weeks of gestation. J Pediatr 1969;74:901-910. [CrossRef][Medline]
Seeds JW, Peng T. Impaired growth and risk of fetal death: is the tenth percentile the appropriate standard? Am J Obstet Gynecol 1998;178:658-669. [CrossRef][Medline]
Jimenez JM, Tyson JE, Reisch JS. Clinical measures of gestational age in normal pregnancies. Obstet Gynecol 1983;61:438-443. [Free Full Text]
Velleman PF. Definition and comparison of robust nonlinear data smoothing algorithms. J Am Stat Assoc 1980;75:609-15.
Kramer MS, Olivier M, McLean FH, Willis DM, Usher RH. Impact of intrauterine growth retardation and body proportionality on fetal and neonatal outcome. Pediatrics 1990;86:707-713. [Free Full Text]
Spinillo A, Capuzzo E, Egbe TO, Fazzi E, Colonna L, Nicola S. Pregnancies complicated by idiopathic intrauterine growth retardation: severity of growth failure, neonatal morbidity and two-year infant neurodevelopmental outcome. J Reprod Med 1995;40:209-215. [Medline]
Laatikainen TJ, Raisanen IJ, Salminen KR. Corticotropin-releasing hormone in amniotic fluid during gestation and labor and in relation to fetal lung maturation. Am J Obstet Gynecol 1988;159:891-895. [Medline]
Piper JM, Xenakis EM, McFarland M, Elliott BD, Berkus MD, Langer O. Do growth-retarded premature infants have different rates of perinatal morbidity and mortality than appropriately grown premature infants? Obstet Gynecol 1996;87:169-174. [Abstract]
Coan, P. M., Fowden, A. L., Constancia, M., Ferguson-Smith, A. C., Burton, G. J., Sibley, C. P.
(2008). Disproportional effects of Igf2 knockout on placental morphology and diffusional exchange characteristics in the mouse. J. Physiol.
586: 5023-5032
[Abstract][Full Text]
Stafford, I., Hernandez, J., Laibl, V., Sheffield, J., Roberts, S., Wendel, G. Jr
(2008). Community-Acquired Methicillin-Resistant Staphylococcus aureus Among Patients With Puerperal Mastitis Requiring Hospitalization. Obstet Gynecol
112: 533-537
[Abstract][Full Text]
Wu, Y.-D., Chen, L.-H., Wu, X.-J., Shang, S.-Q., Lou, J.-T., Du, L.-Z., Zhao, Z.-Y.
(2008). Gram Stain-Specific-Probe-Based Real-Time PCR for Diagnosis and Discrimination of Bacterial Neonatal Sepsis. J. Clin. Microbiol.
46: 2613-2619
[Abstract][Full Text]
Khashan, A. S., McNamee, R., Abel, K. M., Pedersen, M. G., Webb, R. T., Kenny, L. C., Mortensen, P. B., Baker, P. N.
(2008). Reduced Infant Birthweight Consequent Upon Maternal Exposure to Severe Life Events. Psychosom. Med.
70: 688-694
[Abstract][Full Text]
Bukowski, R., Uchida, T., Smith, G. C. S., Malone, F. D., Ball, R. H., Nyberg, D. A., Comstock, C. H., Hankins, G. D. V., Berkowitz, R. L., Gross, S. J., Dugoff, L., Craigo, S. D., Timor, I. E., Carr, S. R., Wolfe, H. M., D'Alton, M. E., for the First and Second Trimester Evaluation of R,
(2008). Individualized Norms of Optimal Fetal Growth: Fetal Growth Potential. Obstet Gynecol
111: 1065-1076
[Abstract][Full Text]
van Eijsden, M., Hornstra, G., van der Wal, M. F, Vrijkotte, T. G., Bonsel, G. J
(2008). Maternal n-3, n-6, and trans fatty acid profile early in pregnancy and term birth weight: a prospective cohort study. Am. J. Clin. Nutr.
87: 887-895
[Abstract][Full Text]
McIntire, D. D., Leveno, K. J.
(2008). Neonatal Mortality and Morbidity Rates in Late Preterm Births Compared With Births at Term. Obstet Gynecol
111: 35-41
[Abstract][Full Text]
Malloy, M. H
(2007). Size for gestational age at birth: impact on risk for sudden infant death and other causes of death, USA 2002. Arch. Dis. Child. Fetal Neonatal Ed.
92: F473-F478
[Abstract][Full Text]
Santiago-Munoz, P. C., McIntire, D. D., Barber, R. G., Megison, S. M., Twickler, D. M., Dashe, J. S.
(2007). Outcomes of Pregnancies With Fetal Gastroschisis. Obstet Gynecol
110: 663-668
[Abstract][Full Text]
Wilson, M. J., Lopez, M., Vargas, M., Julian, C., Tellez, W., Rodriguez, A., Bigham, A., Armaza, J. F., Niermeyer, S., Shriver, M., Vargas, E., Moore, L. G.
(2007). Greater uterine artery blood flow during pregnancy in multigenerational (Andean) than shorter-term (European) high-altitude residents. Am. J. Physiol. Regul. Integr. Comp. Physiol.
293: R1313-R1324
[Abstract][Full Text]
Casey, B. M., Dashe, J. S., Spong, C. Y., McIntire, D. D., Leveno, K. J., Cunningham, G. F.
(2007). Perinatal Significance of Isolated Maternal Hypothyroxinemia Identified in the First Half of Pregnancy. Obstet Gynecol
109: 1129-1135
[Abstract][Full Text]
Evans, N, Hutchinson, J, Simpson, J M, Donoghue, D, Darlow, B, Henderson-Smart, D, on behalf of the Australian and New Zealand Neonat,
(2007). Prenatal predictors of mortality in very preterm infants cared for in the Australian and New Zealand Neonatal Network. Arch. Dis. Child. Fetal Neonatal Ed.
92: F34-F40
[Abstract][Full Text]
Laibl, V. R., Sheffield, J. S., Roberts, S., McIntire, D. D., Wendel, G. D. Jr
(2006). Recurrence of Clinical Chorioamnionitis in Subsequent Pregnancies. Obstet Gynecol
108: 1493-1497
[Abstract][Full Text]
Hunt, S., Craig, J., Russell, A., Guthrie, E., Parsons, L., Robertson, I., Waddell, R., Irwin, B., Morrison, P. J., Morrow, J.
(2006). Levetiracetam in pregnancy: Preliminary experience from the UK Epilepsy and Pregnancy Register. Neurology
67: 1876-1879
[Abstract][Full Text]
Mark, P. J., Waddell, B. J.
(2006). P-Glycoprotein Restricts Access of Cortisol and Dexamethasone to the Glucocorticoid Receptor in Placental BeWo Cells. Endocrinology
147: 5147-5152
[Abstract][Full Text]
Nathanielsz, P. W.
(2006). Decreased placental amino acid transport and intrauterine growth restriction: which is the chicken and which is the egg?. J. Physiol.
576: 649-649
[Full Text]
Wareing, M., Greenwood, S. L., Fyfe, G. K., Baker, P. N.
(2006). Reactivity of Human Placental Chorionic Plate Vessels from Pregnancies Complicated by Intrauterine Growth Restriction (IUGR). Biol. Reprod.
75: 518-523
[Abstract][Full Text]
Stotland, N. E., Cheng, Y. W., Hopkins, L. M., Caughey, A. B.
(2006). Gestational Weight Gain and Adverse Neonatal Outcome Among Term Infants.. Obstet Gynecol
108: 635-643
[Abstract][Full Text]
Feldman, R., Eidelman, A. I.
(2006). Neonatal State Organization, Neuromaturation, Mother-Infant Interaction, and Cognitive Development in Small-for-Gestational-Age Premature Infants. Pediatrics
118: e869-e878
[Abstract][Full Text]
Yang, Q., Greenland, S., Flanders, W. D.
(2006). Associations of Maternal Age- and Parity-Related Factors With Trends in Low-Birthweight Rates: United States, 1980 Through 2000. Am. J. Public Health
96: 856-861
[Abstract][Full Text]
Tang, J. H., Sheffield, J. S., Grimes, J., McElwee, B., Roberts, S. W., Laibl, V., McIntire, D. D., Wendel, G. D. Jr
(2006). Effect of protease inhibitor therapy on glucose intolerance in pregnancy.. Obstet Gynecol
107: 1115-1119
[Abstract][Full Text]
Casey, B. M., Dashe, J. S., Wells, C. E., McIntire, D. D., Leveno, K. J., Cunningham, F. G.
(2006). Subclinical Hyperthyroidism and Pregnancy Outcomes. Obstet Gynecol
107: 337-341
[Abstract][Full Text]
Dashe, J. S., Casey, B. M., Wells, C. E., McIntire, D. D., Byrd, E. W., Leveno, K. J., Cunningham, F. G.
(2005). Thyroid-Stimulating Hormone in Singleton and Twin Pregnancy: Importance of Gestational Age-Specific Reference Ranges. Obstet Gynecol
106: 753-757
[Abstract][Full Text]
Laibl, V. R., Sheffield, J. S., Roberts, S., McIntire, D. D., Trevino, S., Wendel, G. D. Jr
(2005). Clinical Presentation of Community-Acquired Methicillin-Resistant Staphylococcus aureus in Pregnancy. Obstet Gynecol
106: 461-465
[Abstract][Full Text]
Cagnacci, A., Pansini, F. S., Bacchi-Modena, A., Giulini, N., Mollica, G., De Aloysio, D., Vadora, E., Volpe, A., for the Emilia-Romagna Operative Group for the Men,
(2005). Season of birth influences the timing of menopause. Hum Reprod
20: 2190-2193
[Abstract][Full Text]
Yost, N. P., Bloom, S. L., McIntire, D. D., Leveno, K. J.
(2005). Hospitalization for Women With Arrested Preterm Labor: A Randomized Trial. Obstet Gynecol
106: 14-18
[Abstract][Full Text]
Costine, B. A., Inskeep, E. K., Wilson, M. E.
(2005). Growth hormone at breeding modifies conceptus development and postnatal growth in sheep. J ANIM SCI
83: 810-815
[Abstract][Full Text]
Wu, G., Bazer, F. W., Hu, J., Johnson, G. A., Spencer, T. E.
(2005). Polyamine Synthesis from Proline in the Developing Porcine Placenta. Biol. Reprod.
72: 842-850
[Abstract][Full Text]
Kalanda, B F, van Buuren, S, Verhoeff, F H, Brabin, B J
(2005). Anthropometry of fetal growth in rural Malawi in relation to maternal malaria and HIV status. Arch. Dis. Child. Fetal Neonatal Ed.
90: F161-F165
[Abstract][Full Text]
Casey, B. M., Dashe, J. S., Wells, C. E., McIntire, D. D., Byrd, W., Leveno, K. J., Cunningham, F. G.
(2005). Subclinical Hypothyroidism and Pregnancy Outcomes. Obstet Gynecol
105: 239-245
[Abstract][Full Text]
Bartels, D B, Kreienbrock, L, Dammann, O, Wenzlaff, P, Poets, C F
(2005). Population based study on the outcome of small for gestational age newborns. Arch. Dis. Child. Fetal Neonatal Ed.
90: F53-F59
[Abstract][Full Text]
Warner, B., Musial, M. J., Chenier, T., Donovan, E.
(2004). The Effect of Birth Hospital Type on the Outcome of Very Low Birth Weight Infants. Pediatrics
113: 35-41
[Abstract][Full Text]
Christian, P., West, K. P, Khatry, S. K, Leclerq, S. C, Pradhan, E. K, Katz, J., Shrestha, S. R., Sommer, A.
(2003). Effects of maternal micronutrient supplementation on fetal loss and infant mortality: a cluster-randomized trial in Nepal. Am. J. Clin. Nutr.
78: 1194-1202
[Abstract][Full Text]
Durousseau, S., Chavez, G. F.
(2003). Associations of Intrauterine Growth Restriction Among Term Infants and Maternal Pregnancy Intendedness, Initial Happiness About Being Pregnant, and Sense of Control. Pediatrics
111: 1171-1175
[Abstract][Full Text]
Smith-Bindman, R., Chu, P. W., Ecker, J., Feldstein, V. A., Filly, R. A., Bacchetti, P.
(2003). Adverse Birth Outcomes in Relation to Prenatal Sonographic Measurements of Fetal Size. J Ultrasound Med
22: 347-356
[Abstract][Full Text]
Dashe, J. S., Sheffield, J. S., Olscher, D. A., Todd, S. J., Jackson, G. L., Wendel, G. D. Jr
(2002). Relationship Between Maternal Methadone Dosage and Neonatal Withdrawal. Obstet Gynecol
100: 1244-1249
[Abstract][Full Text]
Infante-Rivard, C., Rivard, G.-E., Yotov, W. V., Genin, E., Guiguet, M., Weinberg, C., Gauthier, R., Feoli-Fonseca, J. C.
(2002). Absence of Association of Thrombophilia Polymorphisms with Intrauterine Growth Restriction. NEJM
347: 19-25
[Abstract][Full Text]
Dashe, J. S., McIntire, D. D., Ramus, R. M., Santos-Ramos, R., Twickler, D. M.
(2002). Hydramnios: Anomaly Prevalence and Sonographic Detection. Obstet Gynecol
100: 134-139
[Abstract][Full Text]
Zeeman, G. G., Alexander, J. M., McIntire, D. D., Byrd, W., Leveno, K. J.
(2002). Inhibin-A Levels and Severity of Hypertensive Disorders Due to Pregnancy. Obstet Gynecol
100: 140-144
[Abstract][Full Text]
Smith-Bindman, R., Chu, P. W., Ecker, J. L., Feldstein, V. A., Filly, R. A., Bacchetti, P.
(2002). US Evaluation of Fetal Growth: Prediction of Neonatal Outcomes. Radiology
223: 153-161
[Abstract][Full Text]
Bolt, R. J., van Weissenbruch, M. M., Popp-Snijders, C., Sweep, C. G. J., Lafeber, H. N., Delemarre-van de Waal, H. A.
(2002). Fetal Growth and the Function of the Adrenal Cortex in Preterm Infants. J. Clin. Endocrinol. Metab.
87: 1194-1199
[Abstract][Full Text]
Bloom, S. L., Yost, N. P., McIntire, D. D., Leveno, K. J.
(2001). Recurrence of Preterm Birth in Singleton and Twin Pregnancies. Obstet Gynecol
98: 379-385
[Abstract][Full Text]
Saliba, R. M., Annegers, F. J., Waller, D. K., Tyson, J. E., Mizrahi, E. M.
(2001). Risk Factors for Neonatal Seizures: A Population-based Study, Harris County, Texas, 1992-1994. Am J Epidemiol
154: 14-20
[Abstract][Full Text]
Larroque, B., Bertrais, S., Czernichow, P., Leger, J.
(2001). School Difficulties in 20-Year-Olds Who Were Born Small for Gestational Age at Term in a Regional Cohort Study. Pediatrics
108: 111-115
[Abstract][Full Text]
BLOOM, S. L., SHEFFIELD, J. S., MCINTIRE, D. D., LEVENO, K. J.
(2001). Antenatal Dexamethasone and Decreased Birth Weight. Obstet Gynecol
97: 485-490
[Abstract][Full Text]
BUTLER, E. L., DASHE, J. S., RAMUS, R. M.
(2001). Association Between Maternal Serum Alpha-Fetoprotein and Adverse Outcomes in Pregnancies With Placenta Previa. Obstet Gynecol
97: 35-38
[Abstract][Full Text]
Kohn, M. A., Vosti, C. L., Lezotte, D., Jones, R. H.
(2000). Optimal Gestational Age and Birth-weight Cutoffs to Predict Neonatal Morbidity. Med Decis Making
20: 369-376
[Abstract]
DASHE, J. S., McINTIRE, D. D., LUCAS, M. J., LEVENO, K. J.
(2000). Effects of Symmetric and Asymmetric Fetal Growth on Pregnancy Outcomes. Obstet Gynecol
96: 321-327
[Abstract][Full Text]
ALEXANDER, J. M., MCINTIRE, D. D., LEVENO, K. J.
(2000). Forty Weeks and Beyond: Pregnancy Outcomes by Week of Gestation. Obstet Gynecol
96: 291-294
[Abstract][Full Text]
Wilson, A., Gardner, M. N., Armstrong, M. A., Folck, B. F., Escobar, G. J.
(2000). Neonatal Assisted Ventilation: Predictors, Frequency, and Duration in a Mature Managed Care Organization. Pediatrics
105: 822-830
[Abstract][Full Text]
Strauss, R. S.
(2000). Adult Functional Outcome of Those Born Small for Gestational Age: Twenty-six-Year Follow-up of the 1970 British Birth Cohort. JAMA
283: 625-632
[Abstract][Full Text]
Previous
37 Weeks of Gestation) in Relation to Birth-Weight Percentile.