Epidemiology of high birth weight (HBW) José M. Olmas, MD; Professor of Obstetrics and Master in Maternal-Child Health And Eduardo Halac, MD; Professor of Pediatrics and Perinatal Epidemiology Córdoba National University School of Medicine, Córdoba, Argentina

High Birth Weight Birth weigh is a good indicator to evaluate pre and postnatal development, which also has important short and long term implications on health and survival. Variations detected in birth weight both within and among populations, reflects to a great extent, early human plasticity.

High Birth Weight Although most of the published literature relates to low birth weight (LBW), High BirthWeight (HBW) is now becoming of interest because its long term risks might be of similar importance in term of short and long term consequences, including influences on adult diseases as suggested by Barker’s hypothesis on the Developmental Origin of Health an Adult Diseases (DOHAD).

High Birth Weight Definitions: Any baby whose birth weight exceeds the 90th percentile of local population-based intrauterine growth charts at any given gestational age. Any birth weight >4,5 Kg at any given gestational age.

High Birth Weight Problems with definition: from the epidemiological point of view, HBW lacks a clearcut definition. Instead, LBW babies are rapidly recognized as those weighing <2,5Kg. Because growth charts for newborns are now simple reference patterns derived from cross- sectional data from different countries or even regions in one country, the lack of unifying criteria impairs true estimates of incidence.

High Birth Weight Incidence: until the new WHO sponsored standard neonatal growth charts become available in 2014, estimated frequencies indicate that HBW represents anywhere from 3,5% to 10% of all births. This large variation is probably due to changing definitions applied to different populations.

High Birth Weight Large babies can be born under two different circumstances: Healthy mothers, who are themselves constitutionally large, often married to large fathers.

High Birth Weight Mothers who have either metabolic or genetic problems: most common are the disorders related to carbohydrate intolerance during pregnancy: insulin-dependent diabetes; gestational diabetes, metabolic syndrome; maternal obesity.

High Birth Weight But, is it all in the genes?

Examples of High Birth Weight Constitutionally large infant born to large parents Low –Birth-Weight Infant Infant of gestational diabetic mother

High Birth Weight Less frequently, genetic variants are implicated: Wiedemann-Beckwith and Sotos syndromes, are good examples.

Examples of High Birth Weight Wiedemann Beckwith Syndrome at birth and at age 12 years Sotos Syndrome at 2 months and at 5 years

High Birth Weight Genetic patterns in two set of patients with Widemann- Beckwith Syndrome

High Birth Weight Influence of Maternal Weight Gain during Pregnancy

High Birth Weight A potential risk associated to high birth weight is the higher chances to develop leukemia. Drs. Robert Caughey and Karin Michels form Harvard published in the International Journal of Cancer (2009) their results: an overall risk of developing leukemia 35 times higher for higher birth weight babies than for those of normal birth weight.

High Birth Weight Fifteen-year expected adult weight trajectories by birth weight group in Michigan Bone Health and Metabolism Study women. Normal, low, and high birth weight was defined as 2,500–4,000 g, 4,000 g, respectively. Fifteen-year trajectories were adjusted for participant's age at baseline and were similar in all other body composition measures, except waist-to-hip ratio. Eileen Rillamas-Sun, MaryFran R. Sowers, Siobán D. Harlow and John F. Randolph Jr. Obesity 20, (February 2012)

High Birth Weight Conclusions: Babies born with HBW represent a smaller group than those born with low birth weight. They are, nonetheless, an important public health issue because: 1-They have immediate problems at birth. 2-They are now the focus of larger epidemiological investigations, because long term effects of neonatal macrosomia do not fade; rather, they persist through lifetime increasing the risk of developing obesity, metabolic syndrome, diabetes mellitus and hypertensive disorders.