Researchers from the University of Adelaide, Australia have linked the risk of developing childhood food allergies and eczema to heavier birth weight. The results of this systematic research review were published earlier this week in The Journal of Allergy and Clinical Immunology.
The team of scientists from the university’s Robinson Research Institute, led by Dr. Kathy Gatford, systematically screened more than 15,000 previous studies and found 42 that were eligible for analysis. The eligible studies included 2.1 million people affected by eczema, 70,000 with food allergies, and more than 100,000 with hay fever.
In a press release from the University of Adelaide regarding the study, Dr. Gatford stated that “allergic diseases including eczema, hay fever, food allergies, anaphylaxis, and asthma are estimated to affect 30-40% of the world’s population.” Dr. Gatford and her team aimed to determine additional risks to developing allergies, as she stated that genetics alone do not explain the risks and “environmental exposures before and around birth can program individuals to increased or decreased risk of allergies.”
The results of their analysis showed that a 1 kg (2.2 lb.) increase in birth weight is associated with a 44% greater risk of food allergy in children and a 17% greater risk of allergic dermatitis—eczema—in children. The risk jumps to 34% in infants and children up to two years of age. The risk of developing hay fever was not associated with birth weight.
The team concluded that intrauterine growth restriction protects against allergic diseases. However, Dr. Gatford reiterates that intrauterine growth restriction is associated with increased risks of many diseases later in life. In a statement to Daily Mail regarding the study, Dr. Gatford said, “we don’t want small babies, but we would like to understand how poorer growth or slower growth before birth is protective against allergy.”
Dr. Gatford summarized the study by stating that “the main message for mums is that big babies are at increased risk of allergy.” She further suggests that mothers with “big babies” should learn how to modify their surrounding environment to reduce exposure to allergens and other risk factors.
This study provides evidence for infancy and early childhood. The research team suggests that additional studies in older children and adults are needed to establish how allergic diseases progress or persist with growth.