This page compiles our content related to infant conditions. For further information on diagnosis and treatment, follow the links below to our full BMJ Best Practice topics on the relevant conditions and symptoms.
Introduction
Relevant conditions
Atypical genitalia in neonates | go to our full topic on Atypical genitalia in neonates Atypical genitalia (i.e., a genital phenotype that is neither clearly male nor female) are caused by the atypical development of chromosomal, gonadal, or anatomical sex. The complex group of disorders that cause atypical genitalia are called differences of sex development (DSD). DSD commonly present in the newborn period and can be classified as sex chromosome DSD, 46,XY DSD, or 46,XX DSD. The prevalence of atypical genitalia at birth may be up to 1 in 300 births; however, specialist input is required in about 1 in 3300 births and sex assignment is delayed in 1 in 11,100 births.[1] Risk factors include a family history of consanguinity, genital surgery, infertility, neonatal death, virilisation of a female at puberty (e.g., 5 alpha-reductase deficiency), and other children born with atypical genitalia. Clinical presentations include bilateral impalpable gonads in an apparent male baby, inguinal herniae in an apparent female baby, asymmetric genitalia, micropenis, clitoral enlargement, and hypospadias. |
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Bronchiolitis | go to our full topic on Bronchiolitis Bronchiolitis is an acute infection of the lower respiratory tract. Bronchiolitis is one of the most common acute illnesses in infancy and the leading cause of hospitalisation in this age group.[2][3][4] The most common cause is respiratory syncytial virus (RSV). Bronchiolitis is almost exclusively an infantile disease, and by 3 years essentially all children have serological evidence of having been infected with RSV. Symptoms of bronchiolitis include rhinorrhoea, persistent cough, wheeze, respiratory distress, reduced feeding, and tachypnoea.[5] Key risk factors include infants <3 years, seasonality, prematurity or bronchopulmonary dysplasia, passive tobacco smoke exposure, impaired airway clearance and function, and congenital heart disease. |
Cerebral palsy | go to our full topic on Cerebral palsy An umbrella term referring to a non-progressive disease of the brain originating during the antenatal, neonatal, or early postnatal period that results in disorders of movement and posture development.[6] The incidence of cerebral palsy (CP) in resource-poor countries is around three times higher than that of resource-rich countries due to poor antenatal care, nutritional concerns, and lack of facilities for birth and perinatal services.[7][8] Causes of CP are multifactorial, although in 30% of patients there is no known risk factor or identifiable aetiology. Risk factors for CP may be divided into antenatal (e.g., prematurity, multiple births, and maternal illnesses), perinatal (e.g., birth asphyxia, non-vortex presentation, and birth trauma), and postnatal (e.g., hyperbilirubinaemia, neonatal sepsis, and respiratory distress).[9][10] |
Cleft lip and palate | go to our full topic on Cleft lip and palate An abnormal opening secondary to developmental failure in utero. Cleft lip with or without cleft palate can be unilateral or bilateral, and occurs in a variety of combinations with variable expression in the nose, lip, alveolus, and primary and secondary palates. Cleft lip and palate is the most common congenital cranio-facial anomaly.[11] The aetiology of cleft lip and palate involves a variety of genetic and environmental factors that result in variable expressions of oro-facial clefting. Strong risk factors include genetic predisposition, anticonvulsant drug use during pregnancy, and maternal tobacco use.[12][13] The possible presence of an oro-facial cleft may be revealed by a routine antenatal ultrasound scan at 18 weeks' gestation. The diagnosis of a cleft lip with or without cleft palate involves careful neonatal examination immediately after birth. |
Congenital adrenal hyperplasia | go to our full topic on Congenital adrenal hyperplasia Congenital adrenal hyperplasia (CAH) is a family of inherited enzyme deficiencies that impair normal corticosteroid synthesis by the adrenal cortex. The most common enzyme deficiency is 21-hydroxylase deficiency, which accounts for over 90% of cases. CAH due to 21-hydroxylase deficiency can be classified as either classical or non-classical. CAH is suspected in females who are virilised at birth, who become virilised postnatally, or who have precocious puberty or premature adrenarche. Under-virilisation of newborn males can be seen in 3-beta-hydroxysteroid dehydrogenase deficiency and 17-alpha-hydroxylase deficiency. In addition to symptoms of excess androgen production, infants with classical CAH present with renal salt-wasting. Symptoms include poor feeding, weight loss, failure to thrive, vomiting, dehydration, hypotension, hyponatraemia, and hyperkalaemic metabolic acidosis progressing to adrenal crisis (azotaemia, vascular collapse, shock, and death). Symptoms of non-classical CAH include acne, premature development of pubic hair, early puberty, accelerated growth, advanced bone age, and reduced adult stature as a result of premature epiphyseal fusion. |
Congenital heart disease | go to our full topic on Congenital heart disease The most common birth defect, although still relatively rare. Screening for fetal congenital heart disease (CHD) includes ultrasonography in the second trimester of pregnancy and postnatal clinical examination; however, detection rates are low.[14] The prevalence at birth of CHD globally was 1716.1 per 100,000 babies in 1990 and 1787.6 per 100,000 babies in 2017.[15] CHD is classified into left-to-right shunts (lesions that allow blood to shunt from left side to the right side of the heart), right-to-left shunts (lesions that result in de-oxygenated blood reaching the aorta), and obstructive valvular and non-valvular lesions (e.g., left ventricular outflow tract obstruction, coarctation of the aorta, pulmonary valve stenosis, and aortic valve stenosis). |
Constipation in children | go to our full topic on Constipation in children The infrequent passage of stools leading to one or more of the following: painful defecation; overflow faecal incontinence; rectal faecal impaction; or active defecation avoidance behaviour. Constipation in children is a common problem worldwide.[16] A systematic literature review determined the prevalence of childhood constipation to range from 0.7% to 29.6%.[17] Childhood constipation frequently results from a combination of painful defecation (from any cause) and a rectum of sufficient capacity to allow stools to be withheld.[18] For diagnosis of functional constipation (i.e., no organic cause) in infants up to 4 years - based on the ROME IV criteria - symptoms must include two or more of the following occuring once a week for 1 month: two or fewer defecations per week, history of excessive stool retention or retentive posturing, history of painful or hard bowel movement, and/or presence of a large faecal mass in the rectum.[19][20] Key risk factors include low-fibre intake, poor-nutrient diet, genetic predisposition, infection, stress, obesity, or low birth weight. |
Developmental dysplasia of the hip | go to our full topic on Developmental dysplasia of the hip A spectrum of conditions affecting the proximal femur and acetabulum, ranging from acetabular immaturity to hip subluxation and frank hip dislocation. Estimates of the prevalence of developmental dysplasia of the hip (DDH) in most developed countries vary from 1.5 to 20 cases per 1000 births.[21][22] It is generally believed that genetic, hormonal, and/or mechanical factors play a role in the aetiology of DDH. Strong risk factors for DDH include female sex, positive family history, and antenatal breech presentation.[23] The Barlow and Ortolani screening tests are recommended up to 6 months, although they begin to lose their sensitivity and usefulness around 3-6 months due to increased musculature. Thereafter, limited and/or asymmetric hip abduction suggests the diagnosis. |
Disorders of infant feeding | go to our full topic on Disorders of infant feeding Conditions in children <1 year that lead to impaired oral intake, and are associated with medical, nutritional, feeding skill, and/or psychosocial dysfunction.[24][25] Infant feeding disorders affect 25% to 35% of children with normal development, and up to 80% of children with developmental delay.[26] Feeding disorders occur more commonly in preterm infants than in those born at term.[27] Causes include prematurity; anatomical abnormalities; neuromuscular/neurodevelopmental conditions; gastrointestinal, genetic, cardiac, or respiratory conditions; and behavioural factors. Symptoms include vomiting, abdominal pain, distension, or colic, constipation or diarrhoea, postural changes during feeds, respiratory problems, and atopy. |
Encephalitis | go to our full topic on Encephalitis Inflammation of the brain parenchyma associated with neurological dysfunction, such as altered state of consciousness, seizures, personality changes, cranial nerve palsies, speech problems, and motor and sensory deficits.[28] Globally, the incidence of infectious encephalitis is around 1.5 to 7 cases per 100,000 population per year.[29] Viruses are the main cause of encephalitis, with herpes virus being the most common group of viruses identified. Encephalitis is a medical emergency.[30] An acute or subacute onset of a febrile illness, altered mental status, focal neurological abnormalities, and seizures raises suspicion for this condition. |
Equinovarus foot deformity | go to our full topic on Equinovarus foot deformity Equinovarus foot deformity (EFD), better known as clubfoot, is a relatively common birth defect. It can occur on average in 1 in 1000 live births.[31] The foot has a classic appearance of maximum equinus, as well as varus, adduction, and cavus deformities. The aetiology of EFD is unclear; however, it is likely influenced by both environmental and genetic factors.[32] Strong risk factors include a family history of EFD, male sex, and associated congenital abnormalities. EFD can be identified on antenatal ultrasound (true-positive rate 83%).[33] |
Group B streptococcal infection | go to our full topic on Group B streptococcal infection Group B streptococcal (GBS) infections are the most common cause of early, severe infection in newborns. Common infections in this group include meningitis, sepsis, urinary tract infections, and pneumonia. Gram-positive bacteria are normal commensals of the gastrointestinal tract, female genitourinary tract, and perineum. Colonisation of the respiratory tract can occur in neonates.[34] Approximately 10% to 30% of pregnant women are colonised with GBS in the rectum or vagina; in the absence of intervention, around 60% of babies born to colonised mothers will develop early-onset GBS infection.[35] GBS infection is less common in infants and children. Key risk factors include presence of renal disease, neurological disease, malignancy, and immunosuppression.[36] Sepsis with unknown focus, meningitis, pneumonia, septic arthritis, and peritonitis are the most common presentations in children aged 90 days to 14 years.[36] Diagnosis is confirmed by isolation of the bacterium from a normally sterile site (e.g., blood, cerebrospinal fluid, joint fluid). |
Haemangioma | go to our full topic on Haemangioma Benign vascular lesions that typically appear during the first weeks of life as blue or pink macules or patches. For newborns, the reported incidence is between 1.1% and 2.6%.[37] Infantile haemangiomas are three to five times more likely to occur in girls than in boys.[37] The aetiology of haemangioma is poorly understood. White ethnicity, female sex, prematurity, low birth weight, multiple gestation, and advanced maternal age are strong risk factors for development of haemangioma. Key diagnostic factors include pink, red, or blue vascular lesions, rapid proliferation during the first months of life, variable compressibility (an infantile haemangioma is soft and not fixed), and presentations of flat pink or blue macules or patches. Alternatively, they may present as a red or blue papule or nodule.[38] |
Hirschsprung's disease | go to our full topic on Hirschsprung's disease A congenital condition characterised by partial or complete colonic functional obstruction associated with the absence of ganglion cells.[39][40] The disease occurs in approximately 1 in 5000 births, making it a relatively common congenital problem.[41] Hirschsprung's disease is a genetic disorder with a complex pattern of inheritance.[42][43] Genetic studies have identified 24 associated genes.[44] Infants typically become symptomatic during the first few days of life. Occasionally, a child may have minimal or absent clinical manifestations during the first days or weeks and exhibit moderate, intermittent bouts of symptoms later in life.[45] The most frequent observations are abdominal distention, delayed passage of meconium (not occurring in the first 24-48 hours of life), and vomiting. |
Infantile colic | go to our full topic on Infantile colic Paroxysms of uncontrollable crying or fussing in an otherwise healthy and well-fed infant aged <5 months. The duration of crying is >3 hours per day, and >3 days per week, for at least 3 weeks.[46] Prevalence rates in the literature vary widely from 2% to 73%.[47] The aetiology is not completely understood, but is likely to be multifactorial. Key risk factors include age <5 months, food sensitivity, exposure to cigarette smoke, lack of breastfeeding, and parental psychosocial factors. |
Intussusception | go to our full topic on Intussusception A common cause of intestinal obstruction in young children and is defined as the prolapse of one part of intestine into the lumen of the adjoining distal part.[48] This condition most often occurs in the ileocaecal region. The lead point of the intussusception is most often an enlarged lymph node (Peyer’s patch) in the terminal ileum. Occasionally, the lead point is an anatomic abnormality of the intestine (a 'pathological lead point'). A review of the intussusception literature suggests a mean incidence of 74 per 100,000 among children <1 year, with peak incidence among infants 5-7 months.[49] The aetiology of most cases of intussusception is unclear but is likely to be related to hyperplasia of Peyer's patches and lymphoid tissue in the intestinal wall resulting from antecedent viral infection. Risk factors include male sex and age 6-12 months.[49][50] |
Nappy rash | go to our full topic on Nappy rash Inflammation of the skin in the area of the body covered by a nappy. It is primarily an irritant contact dermatitis. The key irritants are moisture from urine and faeces as well as faecal enzymes (ureases, proteases, and lipases). It is most common in the first 2 years of life, but can occur in a person of any age who routinely wears nappies. Key risk factors include young age (<2 years), history of diarrhoea, underlying dermatological disorder, infrequent nappy changes, excess use of baby care products, plastic underpants, and no nappy-free time. Diagnosis is made by characteristic skin findings in the area of the body covered by a nappy; erythema of the convex surfaces of the buttocks is the classic finding. |
Neonatal jaundice | go to our full topic on Neonatal jaundice Yellowing discoloration of the skin and sclera of a neonate, which is caused by increased levels of bilirubin in the blood. About 50% of term babies and 80% of preterm babies develop jaundice in the first week of life.[51] Key risk factors include Southeast or Far East Asian heritage, maternal diabetes, low birth weight, decreased gestational age, decreased caloric intake and weight loss, and breastfeeding. |
Neonatal sepsis | go to our full topic on Neonatal sepsis Neonatal sepsis is defined as a clinical syndrome of sepsis, and/or isolation of a pathogen in the blood stream, in an infant in the first 28 days of life.[52] It is characterised by derangements in multiple pathobiological processes, which may lead to widespread tissue injury.[53] Group B streptococci and gram-negative bacilli (especially Escherichia coli) are by far the most common causative pathogens in early-onset neonatal sepsis (in first 72 hours of life) and coagulase-negative staphylococci are the most common cause between 72 hours and 1 month of life.[54][55][56] The typical presentation of sepsis varies according to the age of the child. Whereas older children often present with a focus of infection, infants and neonates usually present with non-specific symptoms and signs. For example, a preterm infant in the neonatal intensive unit may demonstrate new onset bradycardic episodes, apnoeas, or feed intolerance as the first signs of sepsis. In the neonatal population, including preterm infants, any change from the patient's normal pattern of observations should raise the suspicion of sepsis. |
Oesophageal atresia and tracheo-oesophageal fistula | go to our full topic on Oesophageal atresia and tracheo-oesophageal fistula Congenital malformations that result from the defective separation of the common embryological precursors to both the oesophagus and trachea. The most common type is a blind-ending upper oesophageal pouch with a fistulous connection between the distal oesophageal segment and the trachea. Approximately one in every 2500 to 4500 births are affected, with a slight female preponderance. The majority of infants have Gross type C, comprising 85% to 90% of all cases. Failure of normal division between the trachea and oesophagus during gestation can result in a spectrum of defects including atresias, fistula formation, and tracheal clefts. Diagnosis is based on clinical suspicion. Newborns generally present with feeding difficulties or respiratory distress. Inability to pass a nasogastric tube is often the first clue of an oesophageal atresia. As antenatal ultrasound has become more common and sensitive, increased numbers of these lesions are being detected in utero. Key risk factors include trisomy 18 and 21 and a family history, which may include Feingold's syndrome. |
Omphalocele and gastroschisis | go to our full topic on Omphalocele and gastroschisis Congenital defects of the abdominal wall resulting in intestinal herniation from the abdominal cavity. In contrast to omphalocele, there is no sac covering the intestines in gastroschisis. The reported incidence of gastroschisis ranges from 3 to 4.5 per 10,000 live births.[57] Some studies suggest that maternal use of recreational drugs may be a risk factor for gastroschisis.[58] Risk factors for abdominal wall defects include smoking and maternal infection during pregnancy. Elevated alpha-fetoprotein levels, measured as part of the routine maternal triple screen at 16 to 18 weeks' gestation, suggest the presence of an abdominal wall defect and warrant further investigation with antenatal ultrasonography.[59] |
Ophthalmia neonatorum | go to our full topic on Ophthalmia neonatorum Conjunctival inflammation occurring within the first 30 days of life. Usually a mild illness. However, untreated infection can lead to sight-threatening complications and potentially serious systemic infection.[60] Patients with suspected neonatal conjunctivitis should be referred immediately for specialist assessment.[61] Complications of neonatal conjunctivitis due to chlamydia include superficial corneal vascularisation, conjunctival scarring, and pneumonia. Complications due to gonorrhoeal infections include corneal scarring, ulceration, panophthalmitis, perforation of the globe, and permanent visual impairment.[60][62] |
Premature newborn care | go to our full topic on Premature newborn care An infant born before 37 completed weeks of gestation. Prematurity is common, with an occurrence of 10.38% of live births in the US in 2022.[63] Almost 85% of preterm infants are born between 32 and 37 weeks’ gestation.[64] The New Ballard Score uses measurements of neuromuscular and physical maturity to complement the maternal history and ultrasonographic findings to estimate gestational age, although a first-trimester ultrasound remains the most accurate assessment of gestational age.[65] |
Pyloric stenosis | go to our full topic on Pyloric stenosis Hypertrophy of the pyloric sphincter resulting in narrowing of the pyloric canal. It is the most common cause of gastric outlet obstruction in the 2- to 12-week-old age group, and leads to progressive and projectile vomiting.[66][67][68][69] No single aetiology is causative of pyloric stenosis. Hyperacidity as a result of antral distention with feeding and hypertrophy of the pylorus from repeated contraction is believed to be a cause of pyloric stenosis.[70] Additionally, poor pyloric muscle neuronal innervation is believed to play a role.[71][72] A family history of pyloric stenosis and first-born male infants are considered key risk factors.[73][74] |
Respiratory syncytial virus infection | go to our full topic on Respiratory syncytial virus infection Respiratory syncytial virus (RSV) is a member of the Pneumoviridae family. It is the most common cause of bronchiolitis. RSV is one of the most important pathogens in early childhood and is the most common cause of bronchiolitis and pneumonia in infancy worldwide.[75][76][77] RSV usually is transmitted by direct or close contact with contaminated secretions, which may occur from exposure to large-particle droplets at short distances (typically <6 feet) or by self-inoculation after touching contaminated surfaces.[78] Key risk factors include exposure to RSV, no recent immunoprophylaxis against RSV, history of prematurity, infants <6 months, chronic lung disease, complex congenital heart disease, immune deficit, winter season, and older age. Immunoprophylaxis with palivizumab or nirsevimab is available for infants and children. |
Spina bifida and neural tube defects | go to our full topic on Spina bifida and neural tube defects Neural tube defects are a spectrum of disorders that can affect the brain or the spinal cord. The most common neural tube defects include anencephaly, which affects brain and skull development and is incompatible with life, and spina bifida, which means 'split spine'. The estimated prevalence of spina bifida and anencephalus in the US is 3.63 and 2.15, respectively, per 10,000 live births.[79] Neural tube defects result from a complex interplay between genetic and environmental factors.[80] Risk factors include trisomy 18, trisomy 13, 22q deletion syndrome, maternal obesity, maternal diabetes, and antenatal exposure to certain medications such as valproate, carbamazepine, isotretinoin, and methotrexate.[81][82][83][84][85] Spina bifida presents clinically with variable paralysis and sensory loss in the legs, orthopaedic deformities, neurogenic bowel and bladder, hydrocephalus, and Chiari II malformation. |
Sudden infant death syndrome | go to our full topic on Sudden infant death syndrome The sudden death of an infant under 1 year with the cause of death unclear after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and a review of the clinical history.[86] Sudden infant death syndrome (SIDS) remains a leading cause of post-neonatal infant death.[87] The frequent autopsy finding of mild upper airway inflammation in suspected cases of SIDS raises the possibility that intercurrent respiratory tract infections have a role in SIDS, particularly in combination with over-bundling.[88] Associations with other modifiable risk factors such as sleeping position, sleeping surface, sleeping arrangements, smoke exposure, not breastfeeding, and non-use of a dummy have been well established, although direct causative roles have yet to be determined.[89] |
Type I glycogen storage disease | go to our full topic on Type I glycogen storage disease Type I glycogen storage disease (GSD I) is a disorder of glucose-6-phosphate breakdown, associated with impaired glycogenolysis and gluconeogenesis. It usually presents during the first year of life, with symptomatic hypoglycaemia when an infant's feeding interval is increased or normal feeding is disrupted by acute illness. GSD I has an estimated incidence of 1 in 100,000 births.[90] Approximately 80% of people with GSD have GSD 1a and 20% have GSD 1b.[90] Clinical features at presentation typically include hepatomegaly, hyperlacticacidaemia, and hypertriglyceridaemia. Symptoms and signs due to neutropenia and neutrophil dysfunction are characteristically seen in GSD type Ib. Family history of GSD I is considered to be a key risk factor. |
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