Home About us Editorial board Search Ahead of print Current issue Archives Submit article Instructions Subscribe Contact us Login 
  • Users Online:85
  • Home
  • Print this page
  • Email this page


 
 Table of Contents  
REVIEW ARTICLE
Year : 2013  |  Volume : 1  |  Issue : 1  |  Page : 33-37

Is maternal age risk factor for low birth weight?


Department of Community Medicine, Yenepoya Medical College, Yenepoya University, Mangalore, Karnataka, India

Date of Web Publication21-Jun-2013

Correspondence Address:
Radha Y Aras
Department of Community Medicine, Yenepoya Medical College, Yenepoya University, Mangalore - 575 018, Karnataka
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2321-4848.113558

Rights and Permissions
  Abstract 

Low birth weight (LBW) is a significant public health concern at global level. LBW is the outcome of interplay of multiple maternal factors. Maternal age is an important variable leading to LBW and preterm births. The literature review was done with extensive search from Medline, the Educational Resources Information Center, and the Combined Health Information Database for publications that identified the studies related to maternal age and birth weight. With exception of few studies which concluded that age did not significantly affect birth weight of newborns, majority of research indicated that a very young maternal age is causally implicated with an increased risk of having LBW and preterm births. Little research has been conducted on births to older mothers, even though such births are becoming increasingly common in developed countries. Advancing maternal age is associated with a decreased potential for fetal growth, possibly reflecting biological aging of maternal tissues and systems or the cumulative effects of disease. Results of multivariate analysis showed a U-shaped relationship between maternal age and LBW among whites, with the youngest (younger than 15) and the oldest (aged 40 and older) mothers being at high risk than 25-29 years old; older teenagers were not at any significantly higher risk. For the black, the risk of LBW rose steeply with maternal age (mothers aged 15-19 years are significantly lower risk than those of 25-29 years for LBW infants).

Keywords: Low birth weight, maternal age, preterm births, risk factor, teenage


How to cite this article:
Aras RY. Is maternal age risk factor for low birth weight?. Arch Med Health Sci 2013;1:33-7

How to cite this URL:
Aras RY. Is maternal age risk factor for low birth weight?. Arch Med Health Sci [serial online] 2013 [cited 2017 Oct 22];1:33-7. Available from: http://www.amhsjournal.org/text.asp?2013/1/1/33/113558


  Introduction Top


Birth weight is the first weight of the fetus or newborn obtained after birth, preferably measured within the first hour of life before significant postnatal weight loss has occurred. Low birth weight (LBW) by international agreement has been defined as a birth weight of less than 2500 grams (WHO1976). [1] According to the WHO's estimate, the global rate of LBW in 2000 was 15.5%, and the rate in developing countries (16.5%) was more than double that of developed countries (7.0%). [2]

A baby's low birth weight is either the result of preterm birth (before 37 completed weeks of gestation) or of restricted fetal (intrauterine) growth. Restricted fetal growth results in small for gestational age babies that are babies born with birth weight below 10 th centile for that gestational age. Low birth weight thus defines a heterogeneous group of infants: Some are born early, some are born growth-restricted, and others are born both early and growth-restricted. It is generally recognized that being born with low birth weight is a disadvantage for the baby. Majority of low birth weight babies are born premature. Preterm birth is the main cause of death, morbidity, and disability.

Mother's age has been suspected of being an important factor in determining birth weight. It is reported that teenage pregnancy have become pressing social concern in the United States, where approximately one million teenagers become pregnant each year and half that number give birth. [3] In Canada, the proportion of live births to women 30 to 34 years of age has risen from 18.9% in 1982 to 31.4% in 2005, while in 35- to 39-year-old women, these proportions have increased from 4.7% to 14.5%. The proportion of live births to women 40 years of age and over has also increased from 0.6% in 1982 to 2.9% in 2005. [4],[5] The mean maternal age at childbirth has increased from 23.7 years in 1969 to 29.2 years in 2005 in Canada, [5] from 25.0 years in 1980 to 27.4 years in 2005 in the United States, [6] and from 28.6 years in 1996 to 29.5 years in 2006 in England and Wales. [7] Japan, Australia, New Zealand, and developed countries in Europe have witnessed similar trends. [8],[9],[10],[11]

LBW is often used as a health indicator. The majority of risk factors have differential effects on birth weight depending on the level of the associated factors. For example, low maternal age and low pre-pregnancy BMI are associated with both increased risk of low birth weight and poor infant survival. [12],[13]

This paper is aimed to review the literature identifying the relationship between the maternal age and the birth weight of infants born to those mothers.


  Materials and Methods Top


A search of periodical literature by the author involving maternal age and birth weight was carried out. Items were identified initially through health-oriented indexing services such as Medline, Health STAR and Cinahl, using the identifiers "Mother's age" and "low birth weight." An extensive search was also carried out on educational database ERIC. Through an electronic search, 57 studies were identified.


  Results and Discussion Top


The low birth weight (LBW) are not only related to the mother's age but also woman's health behaviors during pregnancy or her biologic characteristics, ethnicity, poverty status, age at menarche, maternal height, net maternal weight gain, and smoking during pregnancy had an independent effect on birth weight.

In a study [14] conducted on infants born to US adolescent mother, a hierarchical regression analysis was pursued to evaluate the social disadvantage, biologic immaturity, and unhealthy behaviors during pregnancy; using data from the National Longitudinal Study of Youth on 1,754 first births between 1979 and 1983 to women aged 14-25 years at the time of birth. The birth weights of infants of mothers aged 14-17, 18-19, and 20-23 years were 133, 54, and 88 g less than for infants of mothers aged 23-25. The regression results indicate that the reduced birth weights of infants born to young mothers, particularly women aged 14-17, were related to their disadvantaged social environment. When adjustment was made for poverty and minority status, there were no maternal age differences in birth weight. [14]

A population-based, cross-sectional study of North Carolina births from 1999 to 2003 was performed. Analysis was restricted to 510 288 singleton births from 28 to 42 weeks' gestation with no congenital anomalies. Multivariable linear regression was used to model maternal age and birth order on birth weight, adjusting for infant sex, education, marital status, tobacco use, and race. Results Mean birth weight was lower for non-Hispanic black (NHB) women (3166 g) compared with non-Hispanic white (NHW) women (3409 g) and Hispanic women (3348 g). Controlling for co-variates, birth weight increased with maternal age until the early 30s. Race-specific modeling showed that the upper extremes of maternal age had a significant depressive effect on birth weight for NHW and NHB (35+ years, P < 0.001), but only age less than 25 years was a significant contributor to lower birth weights for Hispanic individuals, P < 0.0001. [15]

In a study conducted at peri-urban slum area of Mumbai, India, pregnancy at teenage was found to be a risk factor for lower birth weight as compared to women between the ages of 21 to 30 years. [16] A hospital-based study in eastern Taiwan reported that teenage mothers gave birth to babies of significantly lower birth weight than adult mothers (19% versus 9%, respectively). [17] Many studies showed that childbearing during adolescence carries an increased risk of poor reproductive outcome, including low birth weight, preterm birth, and neonatal mortality. [18],[19],[20],[21],[22] Some of the explanations proposed for these adverse birth outcomes are biological- i.e. that a pregnant teenager who is still growing may be competing for nutrients with the fetus, or that pregnancy within two years after menarche increases the risk of preterm delivery. [3] Psychological factors may also be involved, since many adolescent pregnancies are unplanned, unwanted, or discovered late. [3],[22] Also, there may exist selection bias, since teenagers who become mothers are more likely than others to be poor, to be undereducated, or to live in areas with limited access to resources and services. [3],[12],[23],[24],[25],[26],[27],[28],[29]

Whether due to young age, unmeasured factors associated with young age, or a combination, teenage multiparas are at increased risk for preterm birth compared with older mothers after controlling for established socio-economic and obstetric risk factors. [30] However, the debate about the contribution of young maternal age to adverse birth outcomes has continued with a recent study [21] demonstrating that young age remains a risk factor for low birth weight (LBW) and preterm birth in first births to teenagers after controlling for confounding socio-economic characteristics. The relative contributions of young age and confounding socio-economic risk factors to poor birth outcomes are even less clear for repeat births to teenagers, partly because much of the research on teenage childbearing has focused on outcomes for first births. [21] In a cross-sectional observational study [31] done on teenage primigravida mothers in a tertiary care hospital in eastern India showed that the teenage mothers had a higher proportion (27.7%) of preterm deliveries compared to 13.1% in the adult mothers and had low-birth-weight babies (38.9% vs. 30.4%, respectively). Roth et al. [32] investigated the incidence of LBW among adolescent mothers in United State of America and gave explanation for the young maternal age - low birth weight gradient, that is, the lower the mother's age, the higher the risk of having LBW baby. In his study, the percentage of LBW babies was highest among mothers with age less than 15 years, that is, 13.7 percent and those mothers with age 15, 16, 17, 18, and 19, the percentage of LBW babies was 11.5, 10.3, 9.6, 9.1, and 8.6, respectively. This is higher than that among mothers with age range between 20 and 44 years. Graham [33] and Jekel et al. [34] found increased LBW in second births to a cohort of teenage mothers. Eisner et al. [35] concluded that maternal age younger than 18 years remains as a risk factor for LBW for multiparas after adjusting for confounding factors. In a retrospective case-control study, Santelli and Jacobson [36] found no increase in LBW for second births compared with first births in a cohort of teenage multiparas. However, this study demonstrated a higher occurrence of LBW to teenage multiparas compared with teenage mothers who postponed a second pregnancy until after adolescence. Finally, Blankson et al. [37] found lower occurrence of fetal growth retardation but higher occurrence of preterm delivery in second births compared with first births in a cohort of low-income teenagers. A possible source of confusion in interpreting findings of past studies is the frequent use of LBW as an outcome measure when 2 distinct causes compose LBW: Prematurity (birth at, 37 weeks' gestation) and small size for gestational age (inadequate intrauterine growth), and the analysis is focused on preterm birth because it accounts for most LBW in the United States (64%). [38]

The common weakness of many studies was the failure to adjust for maternal smoking. Smoking is one of the strongest risk factors for adverse perinatal outcomes, [39] and few studies have shown that pregnant teenagers are more likely to smoke than pregnant older women. [40],[41] The negative effect of maternal smoking on birth weight appears to increase with maternal age. [42]

In a Taiwan study, the overall incidence of LBW was highest (10.6%) among the infants born to younger adolescent mothers (15-17 years of age) and lowest among those whose mothers were 20-34 years of age (5.1%). [43] Also, in this study, the adjusted relative risk of having LBW infants for younger adolescent mothers (15-17 years) and older adolescent mothers (18-19 years) were 2.5 and 1.7, respectively, as compared with mothers 20-34 years of age. [43] Younger adolescent mothers in almost all socio-demographic categories had higher risk of having infants with a LBW than did older adolescent mothers. [43] Both younger and older adolescent mothers who lived in rural areas, who had an age-inappropriate educational level, who had a low/unemployed occupational level, who were married or whose partner had an age-inappropriate educational level, had a significantly higher risk of delivering a LBW infant than mothers who were 20-34 years of age with identical socio-demographic characteristics. [43]

Geronimus [44] demonstrated an increasing risk of low birth weight with advancing maternal age among black, but not white, mothers, using 1989 birth certificate data from singleton first births to black and white mothers aged 15-34 in Michigan. [44]

Teenagers are not the only age group for at high risk for poor birth outcome, but they received the most researchers' attention. Very few research studies have been documented on births to older mothers, even though such births are becoming increasingly common. Virginia et al. [44] reported that older maternal age is associated with reduced birth weight among infants born to African American women, and the age effect is exacerbated by individual poverty. [45]

In a study done by Lee et al. [23] on 184,567 singleton live births with gestational ages of 40 weeks, examined from the 1980-1984 Illinois birth certificate data, it was reported that to separate out the independent effect of maternal age on the incidence of low birth weight infants at term, the presence of other maternal factors, such as race, education, parity, marital status, and prenatal care, were adjusted by use of a series of multiple logistic regression analyses. All of these analyses consistently demonstrated that the adjusted risk for low birth weight at term is the lowest in teenagers and increases with advancing maternal age. These results indicate that the high incidence of this factor in young mothers apparently reflects their poor socio-demographic and prenatal care status. Advancing maternal age is associated with a decreased potential for fetal growth, possibly reflecting biologic aging of maternal tissues and systems or the cumulative effects of disease. [23]

Studies have found that LBW can be predicted by many maternal characteristics, including age and ethnicity. [17],[21],[46],[47],[48],[49],[50],[51] However, the effect of the mother's age on birth weight has been a matter of debate, with some studies reporting that teenage mothers are more likely to give birth to preterm babies and babies of LBW, and others suggesting that other factors such as racial and socio-economic differences may confound such results and weaken any conclusions regarding the effect of age. [21],[47],[52],[53],[54],[55],[56],[57],[58],[59] To assess the true effect of maternal age, researchers need an inclusive set of narrowly defined age groups spanning all reproductive ages across the birth weight.

As this study highlights the fact that the pregnancy at extreme of reproductive age - both young teenagers and older women (after 40 years) - is at high risk for giving birth to low birth weight babies; community-based awareness for prevention of teenage pregnancies (both within the wedlock or out of wedlock) and prevention of pregnancies after 40 years of maternal age; carries important public health significance in reducing low birth weight babies, thus avoiding further consequences among infants with low birth weight.

 
  References Top

1.WHO. Nutrition in Preventive Medicine. WHO Monograph; Geneva, 1976. p. 567.  Back to cited text no. 1
    
2.Wardlaw T, Blanc A, Ahman E .Low Birth weight: Country, Regional and Global Estimate. New York: United Nations Children's Fund and World Health Organization; 2004.  Back to cited text no. 2
    
3.Nancy ER, Deanna LP. Maternal Age and Birth Outcomes: Data from New Jercy. Fam Plnn Perspect 1997;29:268-72.  Back to cited text no. 3
    
4.Health Canada. Canadian Perinatal Health Report, 2003. Cat. No.H49-142/2003E. Ottawa: Minister of Public Works and Government Services Canada; 2003.  Back to cited text no. 4
    
5.Statistics Canada. Births 2005. Cat. No. 84F0210XIE. Ottawa: Ministry of Industry; 2007.   Back to cited text no. 5
    
6.Martin JA, Hamilton BE, Sutton PD, Ventura SJ, Menacker F, Kirmeyer S, et al. Centers for Disease Control and Prevention National Center for Health Statistics National Vital Statistics System. Births: Final data for 2005. Natl Vital Stat Rep 2007;56:1-103.  Back to cited text no. 6
    
7.Office for National Statistics. Birth statistics: Review of the Registrar General on births and patterns of family building in England and Wales, 2006. FM1 No. 35. Newport, South Wales: Office for National Statistics; 2007.  Back to cited text no. 7
    
8.Eurostat. Eurostat yearbook 2002, the statistical guide to Europe: Data 1990-2000. 7 th ed. Luxembourg: Office for Official Publications of the European Communities; 2008.  Back to cited text no. 8
    
9.Eurostat. Europe in figures: Eurostat yearbook 2006-07. Catalogue number: KS-CD-06-001-EN-N. Luxembourg: Office for Official Publications of the European Communities; 2007.  Back to cited text no. 9
    
10.Agerskov U. Nordic Council of Ministers. Nordic statistical yearbook 2007. No. 45. Copenhagen: Nordic Council of Ministers; 2007.  Back to cited text no. 10
    
11.Linacre S. Australian social trends 2007. Catalogue no. 4102.0. Canberra: Australian Bureau of Statistics; 2007.   Back to cited text no. 11
    
12.Cogswell ME, Yip R. The influence of fetal and maternal factors on the distribution of birth weight. Maternal and Child Health Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA. Sem Perinatol 1995;19:222-40.  Back to cited text no. 12
    
13.Aras RY. Teenage Pregnancy-An Epidemiological Perspective. J Fam Welf 1986;33:65-74.  Back to cited text no. 13
    
14.Donna MS, Ensminger ME, Young JK. Mechanisms for Maternal Age Differences in Birth weight. Am J Epidemiol 1995;142:504-14.  Back to cited text no. 14
    
15.Swamy GK, Edwards S, Gelfand A, James SA, Miranda ML. Maternal age, birth order, and race: Differential effects on birth weight. J Epidemiol Community Health 2012;66:136-42.   Back to cited text no. 15
    
16.Aras RY, Baliga A, Pai NP, Jain S, Naimuddin: Pregnancy at Teenage - Risk Factor for lower birth weight. Indian Pediatr 1989;26:823-5.  Back to cited text no. 16
    
17.Li YT, Yin CS, Chan CC Psychosocial risk factors of teenage pregnancy eastern Taiwan. Chin Med J 1999;62:425-30.  Back to cited text no. 17
    
18.Friede A, Baldwin W, Rhodes PH. Young maternal age and infant mortality: The role of low birth weight. Pub Health Rep 1987;102:192-9.  Back to cited text no. 18
    
19.Brown HL, Fan YD, Gonsoulin WJ. Obstetrics complications in young teenagers. South Med J 1991;84:46-8.  Back to cited text no. 19
    
20.McCarthy J, Hardy J. Age at first birth and birth outcomes. Res Adolesc 1993;3:373-92.  Back to cited text no. 20
    
21.Fraser AM, Brockert JE, Hard RH. Association of young maternal age with adverse reproductive outcomes. N Eng J Med 1995;332:1113-7.  Back to cited text no. 21
    
22.Trussell J. Teenage Pregnancy in the United States. Fam Plann Perspect 1988;20:262-72.  Back to cited text no. 22
    
23.Lee KS, Ferguson RM, Corpuz M, Gartner LM. Maternal age and incidence of low birth weight at term: A population study. Am J Obstet Gynecol 1988;158:84-9.  Back to cited text no. 23
    
24.Tsai TS, Chen JY, Lee MC. Reproductive outcomes and infant health in adolescent pregnancy in Taichung city. Acta Paediatr Taiwan 2001;42:151-7.  Back to cited text no. 24
    
25.Geronimus AT, Korenman S. Maternal youth or family background? on the health disadvantages of infants with teenage mothers. Am J Epidemiol 1993;137:213-25.  Back to cited text no. 25
    
26.Strobino DM. Consequences of early sexual and fertility behavior. In: Hofferth SL, Hayes CD, editors. Risking the Future: Adolescent sexuality, pregnancy and child bearing. Washington, DC: National Academy Press; 1987. p. 93-122.  Back to cited text no. 26
    
27.Strobino DM, Ensminger ME, Kim YJ, Nanda J. Mechanisms for maternal Age differences in birth weight. Am J Epidemiol 1995;142:504-14.  Back to cited text no. 27
    
28.Elster AB. The effect of maternal age, parity, and prenatal care on perinatal outcome in adolescent mothers. Am J Obstet Gynecol 1984;149:845-7.  Back to cited text no. 28
    
29.Hofferth SL. Social and economic consequences of teenage childbearing. In: Hofferth SL, Hayes CD, editors. Risking the Future: Adolescent Sexuality, Pregnancy and Childbearing. Washington, DC: National Academy Press; 1987. p. 123-44  Back to cited text no. 29
    
30.Akinbami LJ, Schoendorf KC, Kiely JL. Risk of Preterm Birth in Multiparous Teenagers. Arch Pediatr Adolesc Med 2000;154:1101-7.  Back to cited text no. 30
    
31.Mukhopadhyay P, Chaudhuri RN, Paul B. Hospital-based Perinatal Outcomes and Complications in Teenage Pregnancy in India. J Health Popul Nutr 2010;28:494-500 .  Back to cited text no. 31
    
32. Roth J, Hendrickson J, Schilling M, Stowell DW. The Risk of Teen Mothers Having Low Birth Weight Babies: Implications of Recent Medical Research for School Health Personnel. J Sch Health 1998;68:271-5.  Back to cited text no. 32
    
33.Graham D. The obstetric and neonatal consequences of adolescent pregnancy. Birth Defects Orig Artic Ser 1981;17:49-67.  Back to cited text no. 33
    
34.Jekel JF, Harrison JT, Bancroft DRE, Tyler NC, Klerman LV. A comparison of the health of index and subsequent babies born to school age mothers. Am J Public Health 1975;65:370-4.  Back to cited text no. 34
    
35.Eisner V, Brazie JV, Pratt MW, Hexter AC. The risk of low birth weight. Am J Public Health 1979;69:887-93.  Back to cited text no. 35
    
36.Santelli JS, Jacobson MS. Birth weight outcomes for repeat teenage pregnancy. J Adolesc Health Care 1990;11:240-7.  Back to cited text no. 36
    
37.Blankson ML, Cliver SP, Goldenberg RL, Hickey CA, Jin J, Dubard MB. Health behavior and outcomes in sequential pregnancies of black and white adolescents. JAMA 1993;269:1401-3.  Back to cited text no. 37
    
38.Ventura SJ, Martin JA, Curtin SC, Matthews TJ. Report of Final Natality Statistics, 1996. Hyattsville, Md: National Center for Health Statistics; 1998.  Back to cited text no. 38
    
39.DiFranza JR, Lew RA. Effect of maternal cigarette smoking on pregnancy complications and sudden infant death syndrome. J Fam Pract 1995;40:385-94.  Back to cited text no. 39
    
40.Olausson PM, Cnattingius S, Goldenberg RL. Determinants of poor pregnancy outcomes among teenagers. Sweden. Obstet Gynecol 1997;89:451-7.  Back to cited text no. 40
    
41.Lao TT, Ho LF. Obstetric outcome of teenage pregnancies. Hum Reprod 1998;13:3228-32.  Back to cited text no. 41
    
42.Haug K, Irgens LM, Skjærven R, Markestad TM, Baste V, Schreuder P. Maternal smoking and birth weight: Effect modification of period, maternal age and paternal smoking. Acta Obstet Gynecol Scand 2000;79:485-9.  Back to cited text no. 42
    
43.Lee MC, Suhng LA, Lu TH, Chou MC. Association of parental characteristics with adverse outcomes of adolescent pregnancy. Fam Pract 1998;15:336-42.  Back to cited text no. 43
    
44.Geronimus AT. Black/white differences in the relationship of maternal age to Birth weight: A population-based test of the weathering hypothesis. Soc Sci Med 1996;42:589-97.  Back to cited text no. 44
    
45.Virginia AR, Howard FA, Robin SG. The contribution of maternal age to racial disparities in Birth weight: A Multilevel Perspective. Am J Public Health 2001;91:1815-24.  Back to cited text no. 45
    
46.Vahdaninia M, Tavafian SS, Montazeri A. Correlates of low birth weight in term pregnancies: A retrospective study Iran. BMC Pregnancy Childbirth 2008;8:12.  Back to cited text no. 46
    
47.Olausson PO, Cnattingius S, Haglund B. Teenage pregnancies and risk of late fetal death and infant mortality. Br J Obstet Gynaecol 1999;106:116-21.  Back to cited text no. 47
    
48.Han WH, Chen LM, Li CY. Incidences of predictors for preterm births and low birth weight infants in Taiwan. Chin J Occup Med 2003;10:131-41.   Back to cited text no. 48
    
49.Li YM, Fu CC. Maternal age and adverse pregnancy outcomes-analysis of birth records from 1997 to 1999 in Hualien County. Tzu Chi Med J 2001;13:95-103.  Back to cited text no. 49
    
50.Fu CY, Lu JH, Wu HM. Increased risk for low birth weight and preterm birth in teenage pregnancy. Chin J public Health 1999;18:228-34.   Back to cited text no. 50
    
51.Lee MC, Suhng LA, Lu TH. Association of parental characteristics with adverse outcomes of adolescent pregnancy. Fam Pract 1998;15:336-42.  Back to cited text no. 51
    
52.Lawlor DA, Shaw M. Too much too young? Teenage pregnancy is not a public health problem. Int J Epidemiol 2002;31:552-3.  Back to cited text no. 52
    
53.Rich-Edwards JW, Buka SL, Brennan RT. Diverging associations of maternal age with low birth weight for black and white mothers. Int J Epidemiol 2003;32:83-90.  Back to cited text no. 53
    
54.Richman NE, Pagnini DL. Maternal age and birth outcome: Data from New Jersey. Fam Plan Perspect 1997;29:268-95.  Back to cited text no. 54
    
55.Geronimus AT. Black/white differences in the relationship of maternal age to Birth weight: A population-based test of the weathering hypothesis. Soc Sci Med 1996;42:589-97.  Back to cited text no. 55
    
56.Kale VG. A guide to surgical instruments. 7 th ed. Bombay: Current Book International; 1981. Kirk RM. Basic Surgical techniques. 3 rd ed. London: Churchill Livingstone; 1989.Study. J Public Health 2009;31:131-7.  Back to cited text no. 56
    
57.Savitz DA, Kaufman JS, Dole N. Poverty, education, race, and pregnancy outcome. Ethn Dis 2004;14:322-9.  Back to cited text no. 57
    
58.Pearl M, Braveman P, Abrams B. The relationship of neighborhood socioeconomic characteristics to birth weight among 5 ethnic groups in California. Am J Public Health 2001;91:1808-14.  Back to cited text no. 58
    
59.Parker JD, Schoendorf KC, Kiely JI. Associations between measures of socioeconomic status and low birth weight, small for gestational age, and premature delivery in the United States. Ann Epidemiol 1994;4:271-8.  Back to cited text no. 59
    



This article has been cited by
1 Factors influencing reproduction in captive-bred cynomolgus monkeys (Macaca fascicularis) from Mauritius
Sandiren Naiken,Mary-Ann Griffiths,Lindsay Edouard,Nada Padayatchy
American Journal of Primatology. 2015; 77(12): 1290
[Pubmed] | [DOI]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Materials and Me...
Results and Disc...
References

 Article Access Statistics
    Viewed6591    
    Printed100    
    Emailed0    
    PDF Downloaded796    
    Comments [Add]    
    Cited by others 1    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]