Birth weight

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Baby weighed as appropriate for gestational age.

Birth weight is the body weight of a baby at its birth.[1] The average birth weight in babies of European heritage is 3.5 kilograms (7.7 lb), though the range of normal is between 2.5 kilograms (5.5 lb) and 4.5 kilograms (9.9 lb) (all but 5% of newborns will fall into this range). Babies of south Asian and Chinese heritage weigh about 240 grams (0.53 lb) less.[2][3]

There have been numerous studies that have attempted, with varying degrees of success, to show links between birth weight and later-life conditions, including diabetes, obesity, tobacco smoking and intelligence. Low birth weight is associated with neonatal infection and infant mortality.


There are basically two distinct determinants for birth weight:

  • The duration of gestation prior to birth, that is, the gestational age at which the child is born
Relation of weight and gestational age[where?].
  • The prenatal growth rate, generally measured in relation to what weight is expected for any gestational age.

The incidence of birth weight being outside what is normal is influenced by the parents in numerous ways.

Maternal Health[edit]

The health of the mother, particularly during the pregnancy. Intercurrent diseases in pregnancy are sometimes associated with decreased birth weight. For example, Celiac disease confers an odds ratio of low birth weight of approximately 1.8.[4] Stressful events have been demonstrated to produce significant effects on birth weight. Those mothers who have stressful events during pregnancy, especially during the first and second trimester, are at higher risk to deliver low-birth weight babies. [5] [6]Researchers furthered this study and found that maternal stressful events that occur prior to conception have a negative impact on birth weight as well, and can result in a higher risk for preterm and lower birth weight babies.[7]. [8] [9] Women who experienced abuse (physical, sexual, or emotional) during pregnancy are also at increased risk of delivering a low-birth weight baby. [10] For example, in a study completed by Witt et. al, those women who experienced a stressful event (ie. dealth of close family member, infertility issues, separation from partner) prior to conception had 38 % more of a chance to have a very low birth weight baby compared to those who had not experienced a stressful life event. [7]These findings can pose evidence for future prevention efforts for low birthweight babies. One way to decrease rates of low birth weight and premature delivery is to focus on the health of women prior to conception through reproductive education, screening and counseling regarding mental health issues and stress, and access to primary care.[11]

Environmental and Social Factors[edit]

Environmental factors, including exposure of the mother to secondhand smoke[12] Economic status of the parents gives inconsistent study findings according to a review on 2010, and remains speculative as a determinant.[13] Other factors, like multiple births, where each baby is likely to be outside the AGA (appropriate for gestational age), one more so than the other.



Disability-adjusted life years out of 100,000 lost due to any cause in 2004.[14]
  no data
  less than 9,250
  more than 80,000

Influence on adult life[edit]

Studies have been conducted to investigate how a person's birth weight can influence aspects of their future life. This includes theorised links with obesity, diabetes and intelligence.


A baby born small or large for gestational age (either of the two extremes) is thought to have an increased risk of obesity in later life,[15][16] but it was also shown that this relationship is fully explained by maternal weight.[17]

Growth hormone (GH) therapy at a certain dose induced catch-up of lean body mass (LBM). However percentage body fat decreased in the GH-treated subjects. Bone mineral density SDS measured by DEXA increased significantly in the GH-treated group compared to the untreated subjects, though there is much debate over whether or not SGA (small for gestational age) is significantly adverse to children to warrant inducing catch-up.[18]


Babies that have a low birth weight are thought to have an increased risk of developing type 2 diabetes in later life.[19][20][21] [22]


Some studies have shown a direct link between an increased birth weight and an increased intelligence quotient.[23][24][25] Increased birth weight is also linked to greater risk of developing autism.[26]

Poor neonatal care[edit]

Recent evidence suggests that the effects of low birth weight are constant across developmental years, suggesting that poor neonatal care has long term impacts.[27]

See also[edit]


  1. ^ Definitions Archived April 2, 2012, at the Wayback Machine. from Georgia Department of Public Health. Date: 12/04/2008. Original citation: "Birthweight: Infant's weight recorded at the time of birth"
  2. ^ "New birth weight curves tailored to baby's ethnicity | Toronto Star". Retrieved 2016-09-22.
  3. ^ Janssen, Patricia A; Thiessen, Paul; Klein, Michael C; Whitfield, Michael F; MacNab, Ying C; Cullis-Kuhl, Sue C (2007-07-10). "Standards for the measurement of birth weight, length and head circumference at term in neonates of European, Chinese and South Asian ancestry". Open Medicine. 1 (2): e74–e88. ISSN 1911-2092. PMC 2802014. PMID 20101298.
  4. ^ Tersigni C, Castellani R, de Waure C, et al. (2014). "Celiac disease and reproductive disorders: meta-analysis of epidemiologic associations and potential pathogenic mechanisms". Human Reproduction Update. 20 (4): 582–93. doi:10.1093/humupd/dmu007. PMID 24619876.
  5. ^ Hedegaard, Morten; Henriksen, Tine Brink; Secher, Niels Jergen; Hatch, Maureen C.; Sabroe, Svend (July 1996). "Do Stressful Life Events Affect Duration of Gestation and Risk of Preterm Delivery?". Epidemiology. 7 (4): 339-345.
  6. ^ Zhu, Peng; Tao, Fangbiao; Hao, Jiahu; Sun, Ying; Jiang, Xiaomin (July 2010). "Prenatal life events stress: implications for preterm birth and infant birthweight". American Journal of Obstetrics and Gynocology. 34: 1-7.
  7. ^ a b Witt, Whitney P.; Cheng, Erika R.; Wisk, Lauren E.; Litzelman, Kristin; Chatterjee, Debanjana; Mandell, Kara; Wakeel, Fathima (2014). "Maternal Stressful Life Events Prior to Conception and the Impact on Infant Birth Weight in the United States". American Journal of Public Health. 104 (1): 81-89.
  8. ^ Khashan, A.S.; McNamee, R.; Abel, K.M.; Mortensen, P.B.; Kenny, L.C.; Pedersen, M.G.; Webb, R.T.; Baker, P.N. (2009). "Rates of preterm birth following antenatal maternal exposure to severe life events: a population-based cohort study". Human Reproduction. 24 (2): 429-437. doi:10.1093/humanrep/den418.
  9. ^ Class, Quetzal A.; Khashan, Ali S.; Lichtenstein, Paul; Langstrom, Niklas; D'Onofrio, Brian M. (2013). "Maternal Stress and Infant Mortality: The Importance of the Preconception Period". Psychological Science. 24 (7): 1309-1316. doi:10.1177/0956797612468010.
  10. ^ Murphy, Claire C.; Schei, Berit; Myhr, Terri L.; Du Mont, Janice (May 29, 2001). "Abuse: a risk factor for low birth weight? A systematic review and meta-analysis". Canadian Medical Association Journal. 164 (11): 1567-1572.
  11. ^ Cheng, Tina L.; Kotelchuck, Milton; Guyer, Bernard (2012). "Preconception Women's Health and Pediatrics: An Opportunity to Address Infant Mortality and Family Health". Academic Pediatrics. 12 (5): 357-359.
  12. ^ "The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General". Surgeon General of the United States. 2006-06-27. Retrieved 2014-06-16. pp. 198–205
  13. ^ Margerison Zilko CE (January 2010). "Economic contraction and birth outcomes: an integrative review". Hum Reprod Update. 16 (4): 445–458. doi:10.1093/humupd/dmp059. PMID 20085917.
  14. ^ "WHO Disease and injury country estimates". World Health Organization. 2009. Retrieved Nov 11, 2009.
  15. ^ "3 stages of childhood may predict obesity risk - Fitness -". Retrieved 2007-11-28.
  16. ^ Singhal A, Wells J, Cole TJ, Fewtrell M, Lucas A (1 March 2003). "Programming of lean body mass: a link between birth weight, obesity, and cardiovascular disease?". Am J Clin Nutr. 77 (3): 726–30. PMID 12600868.
  17. ^ Parsons TJ, Power C, Manor O (December 2001). "Fetal and early life growth and body mass index from birth to early adulthood in 1958 British cohort: longitudinal study". BMJ. 323 (7325): 1331–5. doi:10.1136/bmj.323.7325.1331. PMC 60670. PMID 11739217.
  18. ^ "GH Treatment Effects on Body Composition in SGA". Growth, Genetics & Hormones. 24 (1). May 2008.
  19. ^ "Low birth weight diabetes link". BBC News. 2005-02-25. Retrieved 2007-11-28.
  20. ^ Gillman MW, Rifas-Shiman S, Berkey CS, Field AE, Colditz GA (March 2003). "Maternal gestational diabetes, birth weight, and adolescent obesity". Pediatrics. 111 (3): e221–6. doi:10.1542/peds.111.3.e221. PMID 12612275.
  21. ^ Rich-Edwards JW, Colditz GA, Stampfer MJ, et al. (1999). "Birthweight and the risk for type 2 diabetes mellitus in adult women". Ann Intern Med. 130 (4 Pt 1): 278–84. doi:10.7326/0003-4819-130-4_part_1-199902160-00005. PMID 10068385.
  22. ^ Li, Yanping; Ley, Silvia; Tobias, Deirdre; Chiuve, Stephanie; VanderWeele, Tyler (June 17, 2015). "Birth weight and later life adherence to unhealthy lifestyles in predicting type 2 diabetes: prospective cohort study". BMJ. 351: h3673. doi:10.1136/bmj.h3672.
  23. ^ Matte TD, Bresnahan M, Begg MD, Susser E (August 2001). "Influence of variation in birth weight within normal range and within sibships on IQ at age 7 years: cohort study". BMJ. 323 (7308): 310–4. doi:10.1136/bmj.323.7308.310. PMC 37317. PMID 11498487.
  24. ^ "The Future of Children - Sub-Sections". Archived from the original on 2007-10-22. Retrieved 2007-11-28.
  25. ^ Matte TD, Bresnahan M, Begg MD, Susser E (August 2001). "Influence of variation in birth weight within normal range and within sibships on IQ at age 7 years: cohort study". BMJ. 323 (7308): 310–4. doi:10.1136/bmj.323.7308.310. PMC 37317. PMID 11498487. Lay summaryBBC News (August 9, 2001).
  26. ^ Lord C (April 2013). "Fetal and sociocultural environments and autism". The American Journal of Psychiatry. 170 (4): 355–8. doi:10.1176/appi.ajp.2013.13010078. PMID 23545788. Lay summaryScienceDaily (May 2, 2013).
  27. ^ Figlio David; Guryan Jonathan; Karbownik Krzysztof; Roth Jeffrey (2014). "The Effects of Poor Neonatal Health on Children's Cognitive Development". American Economic Review. 104 (12): 3921–55. doi:10.1257/aer.104.12.3921.

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