PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Some infections are more serious in pregnancy than in the non-pregnant state because of the potential for vertical transmission. Infection can pass vertically from mother to fetus/neonate in several ways:
- Across the placenta - infections include Toxoplasma gondii, Treponema pallidum, Listeria monocytogenes, Plasmodium falciparum (malaria), rubella and cytomegalovirus (CMV).
- Ascending maternal infection and chorioamnionitis causing fetal infection, usually subsequent to prolonged rupture of membranes (PROM).
- Perinatal infection acquired during birth via the haematogenous or genital route. These include human immunodeficiency virus (HIV), herpes zoster virus (HZV), hepatitis B virus (HBV) and Chlamydia trachomatis.
- Postnatal infection transmitted via breast-feeding.
Pre-pregnancy or routine antenatal screening can determine the presence or susceptibility to some of these infections, enabling appropriate management to prevent adverse fetal or perinatal outcomes. Always try to consider the possibility of congenital infection when reviewing an unwell pregnant woman.
Screening programmes vary throughout the UK. See the link for the UK Screening Portal Programmes under 'Further reading & references' at the end of this article.
Whilst infections can occur in utero, birth represents an abrupt transition from a highly protected environment to exposure to a vast array of new pathogens ex utero. Parturition also places the baby in direct contact with maternal blood or genital secretions and infections may result, especially if there was prolonged or early rupture of membranes.
At birth, an infant's immune system remains immature. Some protection is provided by maternal antibodies (IgG) crossing the placenta. This process is less complete in the premature baby, especially if markedly premature. If a mother develops a new infection close to the time of birth, she may remain infectious and will not yet have produced any protective IgG, placing the infant at risk of a more severe form of the disease, as in the case of neonatal varicella. The current definitions are:
- Perinatal period - from 24 weeks of gestation to 7 completed days following the time of birth.
- Neonatal period - from birth to 27 completed days, sometimes subdivided into early neonatal (birth to 6 completed days) and late neonatal (day 7 to day 27 completed days).
There is considerable overlap between congenital, perinatal and neonatal infections. Within England, Wales, Northern Ireland and the Crown Dependencies, infection accounts for 5.1% of stillbirths and 10.1% of neonatal deaths.
See the separate article on Rubella and Pregnancy.
Human immunodeficiency virus
See the separate on article Congenital HIV and Childhood AIDS.
See the separate article on Cytomegalovirus.
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See also the separate article on Chickenpox.
- Infection occurs in 1/2,000 pregnancies with a 10-15% risk of fetal infection. The majority of fetal infection is transient and asymptomatic. A minority - 2-3% of infants of women with chickenpox in the first half of pregnancy - does develop varicella syndrome (skin scarring, ipsilateral limb hypoplasia, visceral, neurological and eye lesions).
- Neonatal zoster can occur if the mother is infected 5 days before to 2 days after delivery. It is associated with up to 30% of neonatal mortality. Babies of mothers developing perinatal chickenpox should receive varicella-zoster immune globulin (VZIG).
- Varicella-zoster vaccine is not currently recommended for susceptible women of child-bearing age or for routine use in children in the UK, although it is used widely elsewhere in the world - for example, America and Australia.
See the separate article on Hepatitis B.
See the separate article on Hepatitis C
Group B streptococci
- Group B streptococci (GBS) are found in 12-26% of pregnant women, especially in the urine. Infection has been associated with preterm delivery and ascending infection following rupture of membranes may result in fetal infection.
- Maternal carriage of GBS is associated with a higher risk of chorioamnionitis and neonatal disease.
- Neonatal GBS disease occurs at a rate of 0.5 cases/1,000 births. The rate is increased to 2.3 cases/1,000 births in women with GBS detected in the current pregnancy.
- If GBS was detected in a previous pregnancy, the likelihood of carriage in a subsequent pregnancy is about 38%, with a risk estimate of neonatal GBS disease of approximately 0.9 cases/1,000 births.
- Neonatal sepsis with associated mortality of 6% occurs in 0.5-3.7/1,000 live births. It can be prevented with intrapartum penicillin in high-risk cases.
- Currently there is no consensus regarding preventative strategies - some centres treat on the basis of risk alone (previous history of intrapartum fever, preterm labour, PROM >18 hours), others treat on the combination of screening (third-trimester vaginal and anal swabs) and risk factors.
- Universal screening of all pregnant women, rather than a targeted high-risk approach, may be more effective but even where this occurs, neonatal sepsis still occurs at a level of about 0.5/1,000 live births.
- Preventing neonatal GBS remains controversial:
- Routine bacteriological screening of all pregnant women for antenatal GBS carriage is not recommended.
- Intrapartum antibiotic prophylaxis (IAP), usually in the form of high-dose intravenous (IV) benzylpenicillin or ampicillin, should be offered to women with GBS bacteriuria identified during the current pregnancy.
- IAP should be offered if GBS is detected on a vaginal swab in the current pregnancy.
- IAP should be offered to women with a previous baby with neonatal GBS disease.
- Antibiotic prophylaxis specific for GBS is not required for women undergoing planned caesarean section in the absence of labour and with intact membranes.
- Immediate induction of labour and IAP should be offered to all women known to be colonised with GBS with prelabour rupture of membranes at 37 weeks of gestation or more.
- Women presenting in established preterm labour with intact membranes with no other risk factors for GBS should not routinely be offered IAP unless they are known to be colonised with GBS.
- If chorioamnionitis is suspected, broad-spectrum antibiotic therapy including an agent active against GBS should replace GBS-specific IAP and induction of labour should be considered.
See the separate article on Listeriosis.
See the separate article on Syphilis.
- 0.02% of pregnant women are infected with syphilis in the UK but screening, even with such low incidence, remains cost-effective. Syphilis remains endemic in many other parts of the world (Africa, Southeast Asia and ex-USSR).
- Transplacental transmission occurs in 90% of untreated women, with highest risk early in the disease. At birth, infection manifests as neonatal rhinitis, osteitis, and skin bullae. Hutchinson's triad (abnormal teeth, interstitial keratitis and sensorineural deafness) arises later in untreated children.
- Maternal infection is usually detected by antenatal screening using a non-treponemal test (eg, VDRL) but note there is a risk of false-positive results (due to concomitant infection or autoimmune disease) and confirmation with a specific treponemal test (eg, FTA-ABS) is required.
- Treatment is with parenteral benzylpenicillin.
Chlamydia affects 5-7% of pregnant women and is usually asymptomatic. The main symptom of neonatal infection is conjunctivitis (occurs in 50% of exposed infants) and, more rarely, a pneumonia at about 4-6 weeks old.
See also the separate article on Gonorrhoea.
Gonorrhoea is usually asymptomatic in pregnancy. Gonococcal cervicitis is associated with chorioamnionitis and increased risk of premature labour. 40% of untreated maternal cases cause ophthalmia neonatorum - presenting with purulent discharge, lid swelling, and corneal hazing within 4 days of birth.
See also the separate article on Toxoplasmosis.
About 75% of pregnant women are susceptible but seroconversion during pregnancy is uncommon. A third of infants become infected if their mother becomes infected during pregnancy, especially in later pregnancy (but the severity of disease decreases). There is very little good evidence that prenatal education reduces the risk of congenital infection.
See the separate article on Malaria in Pregnancy.
Routine antenatal screening tests in the UK completed prior to 16 weeks of gestation 
|Hepatitis B surface antigen||To determine chronic carriers.||If positive, administer hepatitis B immune globulin and vaccine to the infant at birth (prevents carriage in 95%).|
|Syphilis||To detect active infection.||If reactive, treat with penicillin and consult a GUM specialist.|
|HIV antibody||To enable measures to be taken to reduce vertical transmission.||If positive, antiretroviral treatment for both mother and infant reduces vertical transmission rates significantly. Refer to a GUM/HIV specialist.|
|Urine culture||Treatment of asymptomatic urinary tract infection is thought to reduce adverse pregnancy outcomes (premature labour) and risk of maternal pyelonephritis.||If culture shows asymptomatic bacteriuria, treat with antibiotics and repeat culture to ensure fully treated.|
Surveillance indicates that rates of maternal infection are variable across the country with high concentrations in particular geographical areas. Based on data from women receiving antenatal care in London between 2000-2007, prevalence of HIV infection was 3/1,000 women, of hepatitis B was 11/1,000, of syphilis was 4/1,000 and of rubella susceptibility was 39/1,000. Uptake of screening amongst this group of pregnant women was between 95-97%.
Currently there are no tests recommended nationally for antenatal screening of CMV, toxoplasma, parvovirus or GBS.
Do not forget that acute maternal infection may occur after screening - in resource-rich settings such as the UK and America, a significant proportion of perinatal transmission of HIV occurs due to infection acquired during pregnancy.
Serious acute neonatal infections
- The incidence of serious acute infections in neonates is around 2/1,000 live births but the figure rises to 8-9/1,000 in small babies weighing just 1,000 to 2,000 grams and 26/1,000 in those of less than 1,000 grams. GBS is the most frequent cause of severe early-onset neonatal infection in neonates and occurs in 0.5/1,000 UK births.
- Of early-onset neonatal sepsis, 85% presents in the first 24 hours, 5% between 24 and 48 hours, and the remaining 10% over the subsequent 4 days. Early-onset infections include GBS, Escherichia. coli, Haemophilus influenzae, and Listeria monocytogenes and are most likely to have been acquired transplacentally, by ascending or intrapartum infection.
- Diagnosis is complicated by the lack of clear clinical features of infection and very poor localising features. The lack of an effective immune response in the neonate means that infection can spread, rapidly causing significant damage to organs.
If a baby needs antibiotic treatment it should be given as soon as possible and always within 1 hour of the decision to treat.
Serious neonatal infections include:
- In the early neonatal period, the most common organisms causing septicaemia are E. coli and GBS. Later, coagulase-negative staphylococci (frequently meticillin-resistant) predominate.
- Blind treatment is with a penicillin plus gentamicin or cefotaxime/cefuroxime. Vancomycin plus gentamicin is used in late-onset sepsis if meticillin-resistant Staphylococcus aureus (MRSA) is found or suspected.
- Typical signs found in older children or adults are not present in a small infant. There may possibly be a bulging fontanelle but this is unreliable and features such as Kernig's sign and neck stiffness are of no value.
- There may be depressed consciousness or convulsions.
- If there is any doubt, a lumbar puncture should be performed, as failure to treat meningitis has such serious consequences.
- The implicated organisms are totally different in the neonate from older patients. GBS and E. coli are responsible for around two thirds of cases.
- This may be acquired through aspiration of the micro-organisms during the delivery process.
- Infection causes pulmonary changes with infiltration, and destruction of bronchopulmonary tissue. Fibrinous exudation into the alveoli leads to inhibition of pulmonary surfactant function and respiratory failure with a presentation very similar to respiratory distress syndrome (RDS).
- Differentiating RDS from infection in a premature baby can be very difficult. Segmental or lobar atelectasis, seen on CXR, may occur in both.
- Urinary tract infection:
- Symptoms are similar to the nonspecific ones of other serious acute infections.
- Diagnosis is by examination of a urine sample, if necessary obtained by suprapubic bladder aspiration.
- Treatment should start immediately in the ill child, purely on clinical suspicion.
- Use IV cefotaxime or an aminoglycoside with careful monitoring of blood levels.
- After successful treatment, the urinary tract should be checked for congenital abnormalities.
Clinical indicators of possible-early-onset neonatal infection
- Respiratory distress starting more than 4 hours after birth.
- The need for mechanical ventilation in a term baby.
- Signs of shock.
Other possible indicators include:
- Altered behaviour or responsiveness.
- Altered muscle tone - eg, floppiness.
- Feeding difficulties.
- Feed intolerance, including vomiting, excessive gastric aspirates and abdominal distension.
- Abnormal heart rate (bradycardia or tachycardia).
- Signs of respiratory distress.
- Hypoxia - eg, central cyanosis or reduced oxygen saturation level.
- Jaundice within 24 hours of birth.
- Signs of neonatal encephalopathy.
- The need for cardiopulmonary resuscitation.
- The need for mechanical ventilation in a preterm baby.
- Persistent fetal circulation (persistent pulmonary hypertension).
- Temperature abnormality (lower than 36°C or higher than 38°C) unexplained by environmental factors.
- Unexplained excessive bleeding, thrombocytopenia, or abnormal coagulation.
- Oliguria persisting beyond 24 hours after birth.
- Altered glucose homeostasis (hypoglycaemia or hyperglycaemia).
- Metabolic acidosis (base deficit of 10 mmol/L or greater).
- Local signs of infection - eg, affecting the skin or eye.
In those under four weeks old, temperature should be taken by an electronic thermometer in the axilla. A fever of 38°C or more in this age group indicates high risk of serious illness.
Some highly sophisticated markers to rule in or rule out sepsis may be used in specialist units. Inborn errors of metabolism or congenital abnormalities of the cardiovascular or respiratory systems may present in a similar manner to infection.
Investigations should include:
- FBC. White count is very nonspecific and platelets are often low in infection.
- Blood cultures.
- Urine culture.
- Ear, nose and throat swabs.
- Swabs from any obvious sites of infection.
- Lumbar puncture - should be used quite readily.
- CXR with respiratory signs.
- Blood gases.
Serious neonatal infection has a bad prognostic implication for neuro-development and delay is common. This is especially so if the infant is premature. The inflammatory mediators may have an important role in neurotoxicity. There may also have been hypoxia. Oxygen therapy has to be monitored very carefully in infants, especially if premature, as excessive oxygen can cause retrolental fibroplasia. Any baby that has received an aminoglycoside should have hearing assessed. See the separate article on Premature Babies and their Problems.
Skin infections with S. aureus are common. Periumbilical skin infections present a special risk because of the possibility of bacteria passing up the umbilical vein, causing thrombophlebitis and even an hepatic abscess. Infection appears as:
- Pustules - singly or in multiples, without associated redness, almost anywhere on the skin. They can cause a problem in the axillae or groin but rarely spread. They should be treated with antiseptic powder to prevent cross infection.
- Bullous impetigo is less common but potentially far more serious. This presents as large pus-filled blisters that burst to form scabs. Where large areas of skin are involved, the condition is known as scalded skin syndrome. Treatment is with flucloxacillin, IV if necessary, and fluid replacement.
- Paronychia is infection of the nail fold and often involves more than one finger. It may produce pus. Treatment is with an antistaphylococcal cream.
- Acute mastitis is strictly an infection of subcutaneous tissue presenting with swelling, inflammation and fever. Treatment is with flucloxacillin and drainage of the abscess if needed.
An increasing problem is of MRSA. These organisms may be transmitted perinatally from the mother's skin or genital tract or nosocomially, particularly among premature or sick infants, or acquired in the community after discharge from hospital.
See the separate article on Ophthalmia Neonatorum.
- Candida albicans is a common commensal, but infection may affect the tongue and the rest of the mouth. It can spread to the gastrointestinal tract, causing diarrhoea and vomiting.
- It presents as a large number of firmly adherent, small, white plaques that may interfere with feeding by making the mouth sore.
- If the lesions are scraped with a tongue spatula, they will readily shift if they are only milk curds but thrush will be adherent.
- Treatment is with a topical antifungal such as nystatin suspension.
Herpes simplex virus (HSV):
See also the Encephalitis article.
- Neonatal HSV infection is rare (approximately 1-2/100,000 deliveries) but devastating. It is acquired from the mother during vaginal delivery and mainly infects the eye, skin or mouth.
- It can also cause a systemic infection producing meningoencephalitis with jaundice and hepatosplenomegaly, and sometimes bleeding.
- Diagnosis is by viral culture and treatment is with IV aciclovir.
- Neonates with HSV infection acquired perinatally have a 65% mortality rate (untreated), reduced to 25% with treatment.
- Elective caesarean section can reduce the risk of infant exposure to infected secretions during birth and has become the standard of care for women with symptomatic lesions. However, most neonatal infections occur with asymptomatic mothers, who are subclinically shedding virus.
- Studies suggest that giving pregnant women with primary genital herpes infection or recurrences, aciclovir from 36 weeks of gestation prevents recurrence and reduces the risk of peripartum HSV shedding, thereby reducing the need for caesarean section.
- The best strategy for detecting pregnant women at risk of peripartum HSV shedding remains controversial and screening is not currently recommended.
Varicella-zoster virus (VZV):
See also the separate article on Varicella.
- Maternal infection in the perinatal period carries a risk of severe neonatal varicella, with a mortality rate of 30%. Approximately a quarter of neonates will develop clinical chickenpox if their mother develops chickenpox or shingles in the month before delivery.
- However, the highest risk of severe neonatal illness is where the mother develops infection from 5 days before delivery to 2 days afterwards.
- Babies of mothers developing perinatal chickenpox from a week before to a week after birth should receive varicella-zoster immune globulin (VZIG) as it prevents clinically-apparent chickenpox in approximately half of neonates born to mothers with chickenpox around the time of delivery and reduces the severity where the disease is not prevented.
- If the baby has developed the varicella rash, VZIG is not helpful and treatment for neonatal chickenpox should be started with aciclovir.
- Coxsackie infection of type B appears as sporadic outbreaks in maternity unit with meningoencephalitis and acute myocarditis.
- Echovirus infection often presents with gastroenteritis but can affect any system, with symptoms that range from slight illness to severe sepsis. Usually no treatment is required but immunoglobulins can be used in severe cases.
Tuberculosis can be acquired from the mother very early in life and may present around 6 weeks of life with unwillingness to feed, excessive weight loss, slight fever and hepatosplenomegaly. CXR is required. Obtaining samples such as sputum is impractical in babies. Remember this possibility in those from high-risk groups. Treatment is with standard antituberculous drugs. If there has been tuberculosis in the family in the previous 6 months, BCG is given at 3 days - see the separate article on Immunisation Schedule (UK).
Further reading & references
- Perinatal Mortality 2009; Centre for Maternal and Child Enquiries (CMACE), March 2011
- Gilbert GL; 1: Infections in pregnant women.; Med J Aust. 2002 Mar 4;176(5):229-36.
- Daley AJ, Thorpe S, Garland SM; Varicella and the pregnant woman: prevention and management. Aust N Z J Obstet Gynaecol. 2008 Feb;48(1):26-33.
- Prevention of Early Onset Neonatal Group B Streptococcal Disease; Royal College of Obstretricians and Gynaecologists (2012)
- Eberly MD, Rajnik M; The effect of universal maternal screening on the incidence of neonatal early-onset group B streptococcal disease. Clin Pediatr (Phila). 2009 May;48(4):369-75. Epub 2008 Oct 2.
- Warrell D, Cox TM, Firth JD, Benz E. Oxford Textbook of Medicine, 4th edition. 2004. OUP. ISBN 0198529988
- Walker DG, Walker GJ; Forgotten but not gone: the continuing scourge of congenital syphilis. Lancet Infect Dis. 2002 Jul;2(7):432-6.
- Di Bartolomeo S, Mirta DH, Janer M, et al; Incidence of Chlamydia trachomatis and other potential pathogens in neonatal conjunctivitis.; Int J Infect Dis. 2001;5(3):139-43.
- Di Mario S, Basevi V, Gagliotti C, et al; Prenatal education for congenital toxoplasmosis. Cochrane Database Syst Rev. 2009 Jan 21;(1):CD006171.
- Antenatal care for uncomplicated pregnancies; NICE Clinical Guideline (March 2008)
- Giraudon I, Forde J, Maguire H, et al; Antenatal screening and prevalence of infection: surveillance in London, 2000-2007. Euro Surveill. 2009 Mar 5;14(9):8-12.
- Patterson KB, Leone PA, Fiscus SA, et al; Frequent detection of acute HIV infection in pregnant women. AIDS. 2007 Nov 12;21(17):2303-8.
- Anderson-Berry AL et al; Neonatal Sepsis, Medscape, Jul 2012
- Antibiotics for early-onset neonatal infection, NICE Clinical Guideline (August 2012)
- Feverish illness in children - Assessment and initial management in children younger than 5 years; NICE Guideline (May 2013)
- Ng PC, Lam HS; Diagnostic markers for neonatal sepsis. Curr Opin Pediatr. 2006 Apr;18(2):125-31.
- Adams-Chapman I, Stoll BJ; Neonatal infection and long-term neurodevelopmental outcome in the preterm infant. Curr Opin Infect Dis. 2006 Jun;19(3):290-7.
- Pinter DM, Mandel J, Hulten KG, et al; Maternal-infant perinatal transmission of methicillin-resistant and methicillin-sensitive Staphylococcus aureus. Am J Perinatol. 2009 Feb;26(2):145-51. Epub 2008 Oct 31.
- Kimberlin DW; Neonatal herpes simplex infection. Clin Microbiol Rev. 2004 Jan;17(1):1-13.
- Gupta R, Warren T, Wald A; Genital herpes. Lancet. 2007 Dec 22; 370(9605):2127-37.
- Chickenpox in pregnancy; Royal College of Obstetricians and Gynaecologists (September 2007)
- Tebruegge M, Pantazidou A, Curtis N; Towards evidence based medicine for paediatricians. How effective is varicella-zoster immunoglobulin (VZIG) in preventing chickenpox in neonates following perinatal exposure? Arch Dis Child. 2009 Jul;94(7):559-61.
- Bryant PA, Tingay D, Dargaville PA, et al; Neonatal coxsackie B virus infection-a treatable disease? Eur J Pediatr. 2004 Apr;163(4-5):223-8. Epub 2004 Feb 18.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Chloe Borton
Dr Colin Tidy
Dr Adrian Bonsall