Neonatal hypoglycemia
Vascular lesions including nevus simplex (typically appearing on the forehead, glabella, and/or back of the neck) or hemangiomas (cutaneous or extracutaneous)
Characteristic facies including midface retrusion and infraorbital creases
Structural cardiac anomalies or cardiomegaly
Diastasis recti
Advanced bone age (common in overgrowth/endocrine disorders)The diagnosis of BWS is established in a proband with either of the following:

Three major or two major plus at least one minor criteria  Note: BWS should be considered a clinical spectrum, with some affected individuals having only one or two suggestive clinical findings. Therefore, the generally accepted clinical criteria proposed here should not be viewed as absolute but rather as guidelines. In other words, they cannot be used to rule out a diagnosis of BWS and cannot substitute for clinical judgment. An epigenetic or genomic alteration leading to abnormal methylation at 11p15.5 or a heterozygous BWS-causing pathogenic variant in CDKN1C in the presence of one or more clinical findingsMost children with BWS do not have all of these features. In addition, some children with BWS have other findings including: nevus flammeus, prominent occiput, midface hypoplasia, hemihypertrophy, genitourinary anomalies (enlarged kidneys), cardiac anomalies, musculoskeletal abnormalities, and hearing loss. Also, some premature newborns with BWS do not have macroglossia until closer to their anticipated delivery date.Given the variation among individuals with BWS and the lack of a simple diagnostic test, identifying BWS can be difficult. In an attempt to standardize the classification of BWS, DeBaun et al.
Hypoglycemia in newborns with BWS should be managed according to standard protocols for treating neonatal hypoglycemia. Usually this hypoglycemia can easily be treated with more frequent feedings or medical doses of glucose. Rarely (<5%) children with BWS will continue to have hypoglycemia after the neonatal period and require more intensive treatment. Such children may require tube feedings, oral hyperglycemic medicines, or a partial pancreatectomy.Macroglossia, a large tongue, is a very common (>90%) and prominent feature of BWS. Infants with BWS and macroglossia typically cannot fully close their mouth in front of their large tongue, causing it to protrude out. Macroglossia in BWS becomes less noticeable with age and often requires no treatment; but it does cause problems for some children with BWS. In severe cases, macroglossia can cause respiratory, feeding, and speech difficulties. Children with BWS and significant macroglossia should be evaluated by a craniofacial team.The best time to perform surgery for a large tongue is not known. Some surgeons recommend performing the surgery between 3 and 6 months of age. Surgery for macroglossia involves removing a small part of the tongue so that it fits within the mouth  to allow for proper jaw and tooth development.These children are often managed by a multidisciplinary craniofacial team. These teams include speech and language therapists, Craniofacial and Paediatric Plastic Surgeons and Orthodontists who decide the appropriateness and timing of tongue reduction surgery. Some countries have designated centres for the management of macroglossia.