Maternal infections

Published on 03/06/2015 by admin

Filed under Neonatal - Perinatal Medicine

Last modified 22/04/2025

Print this page

This article have been viewed 1517 times

CHAPTER 26 Maternal infections

Garry Inglis, Mark Davies, David Cartwright

Viral disorders

Hepatitis B

Mothers who are positive for hepatitis B surface antigen (HBsAg) are at risk of passing the virus to their infants (risk 5–20%). The risk is estimated to be between 70% and 90% if they also have the hepatitis B e antigen (HBeAg).

The time of most risk for the infant is the birth process, when the infant comes into contact with maternal blood and secretions. Antenatal transmission is very rare. Infants who acquire hepatitis B have >90% chance of chronic infection.

Prophylaxis

• For babies born to HBsAg-positive mothers, the generally accepted approach is to give the baby hepatitis B immunoglobulin (100 IU, intramuscular, in Australia) as well as the hepatitis B immunisation in the opposite limb. Immunoglobulin should ideally be given before 12 hours of age. This regimen results in >90% protection.

• Before commencing the above schedule, it should be discussed with the parents, or at least the mother, when possible. However, if the mother is unavailable (e.g. after a general anaesthetic), the immunoglobulin should be given anyway. This is just as important as treating pneumonia with antibiotics.

• Serology testing of the infant should not be done before 9 months of age.

• Breastfeeding is not contraindicated.

Immunisation

The most effective way of preventing hepatitis B infection is immunisation prior to exposure to the virus. Routine immunisation in infancy has been introduced in some countries.

• In Australia, this begins at birth and the dose is 5 μg, given by intramuscular injection. Other countries use 10 μg.

• Immunisation should be administered in hospital prior to discharge (when the baby is ‘physiologically stable’) and preferably in the first 24 hours of life.

Babies admitted to our intensive care nursery are deemed to be ‘physiologically stable’ at the time of their discharge/transfer from intensive care. These babies could be going to the postnatal ward, to another hospital, or to the special care nursery. For those admitted to our special care nursery the immunisation will be given when ‘physiologically stable’ as decided by the medical staff.

• The rate of seroconversion following primary immunisation in children is close to 100%, therefore serology testing is not required.

Note that for babies born in Australia at <32 weeks gestational age (GA), hepatitis B immunisation will not be given until the first general immunisation time at 2 months of age, except to those whose mothers are HBsAg-positive for whom hepatitis B vaccination will be given as per the program for term infants.

Some countries adopt a risk-based approach to immunisation, where babies are offered hepatitis B immunisation if they fall into high-risk populations such as certain ethnic groups, or those whose mothers have a history of intravenous drug use.

Hepatitis C virus (HCV)

The risk of vertical transmission from a HCV-infected mother to her baby is approximately 5%. There is inadequate evidence currently available to support the use of prophylactic immunoglobulin for infants born to HCV-infected mothers.

• Breastfeeding is not contraindicated but should be stopped if the mother’s nipples are cracked or bleeding.

• There is currently no uniform recommendation for how and when to screen infants born to HCV-positive mothers. Some recommend serology between 6 and 12 months, but specificity is low because passively transferred maternal antibodies can persist until about 18 months. Others delay serology testing until after 18 months. HCV PCR may be available but has been shown to have low sensitivity in the first few months after birth.

Varicella

• Zoster immunoglobulin (ZIG) should be given to any baby whose mother develops varicella up to 7 days before delivery or up to 28 days after delivery.

— ZIG should be given to the baby as soon after the delivery as possible and must be given within 72 hours.

— Follow up all babies who are given ZIG. They should be admitted to hospital if any rash develops.

• Intravenous aciclovir should be given:

— to babies presenting with chickenpox who are unwell (e.g. poor feeding, tachypnoea), whether or not they received ZIG

— to any high-risk neonate who develops chickenpox and who inadvertently did not receive ZIG prophylaxis or for whom it was delayed beyond 24 hours

— to immunocompromised neonates who develop chickenpox, including those who are premature or being treated with corticosteroids.

• There is no evidence to support the use of routine aciclovir prophylaxis in conjunction with ZIG and it is not currently recommended in neonates.

• Breastfeeding of infected or exposed babies is encouraged.

• A mother and/or her baby with active vesicles should be isolated from other mothers and babies, but an infected mother does not need to be isolated from her own baby.

[Heuchan A, Isaacs D, on behalf of the Australasian Subgroup in Paediatric Infectious Diseases of the Australasian Society for Infectious Diseases. The management of varicella-zoster virus exposure and infection in pregnancy and the newborn period. Med J Australia 2001;174:288–292.]

Herpes

Neonatal herpes simplex virus (HSV) infection can manifest as mucocutaneous disease, central nervous system (CNS) disease, or disseminated multi-organ disease. The risk of mortality in infected neonates is high and survivors have a high risk of long-term morbidity. Most affected infants will be born to asymptomatic mothers or mothers with no documented history of herpes infection.

• The risk of transmission from an infected mother to her vaginally delivered baby is estimated to be <5% for active recurrent genital herpes, and up to 50% for primary infection. For infants delivered by Caesarean section with membranes ruptured for less than 4 hours, the transmission risk is very low.

• All infants born to mothers with active herpes infection should be carefully examined and observed for signs of infection.

• Infants born to mothers with recurrent infection, and who have no signs of infection, are not routinely treated with aciclovir.

There are two general approaches to infants born to mothers with primary genital infection.

1. The first approach is to collect swabs within 48 hours of birth from the mouth, conjunctivae, nasopharynx and rectum for HSV PCR (polymease chain reaction) or culture — if positive then treat with aciclovir.

2. The alternative approach is to treat all babies with aciclovir from birth after collecting swabs as above.

When collecting a swab from a skin lesion, de-roof the lesion and swab from the base.

Any infant who develops clinical evidence of herpes should be treated immediately. If infection is suspected then HSV culture or PCR should be obtained on skin lesion fluid, stool, urine, blood buffy coat and cerebrospinal fluid (CSF).

• Treatment consists of intravenous aciclovir 20 mg/kg/dose every 8 hours for 14 days (mucocutaneous disease only) or 21 days (disseminated or CNS disease).

Human immunodeficiency virus (HIV)

HIV screening in pregnancy is routine in some places. Pregnant women known to be HIV-positive should be treated during pregnancy and labour. Caesarean delivery before membrane rupture has been shown to reduce the risk of transmission.

• Babies born to HIV-positive mothers should be treated with zidovudine (2 mg/kg every 6 hours orally) for the first 6 weeks of life. This has been shown to reduce the risk of transmission by about two-thirds.

• HIV screening of the infant by DNA PCR (polymease chain reaction) should be done in the first few days of life and repeated at 1–2 and 4 months.

• In developed countries breastfeeding should be discouraged because of the risk of transmission.

Syphilis

• Infants born to mothers with a history of adequately treated syphilis (who have not been reinfected) usually require no specific treatment but must be evaluated for evidence of infection: examine the infant carefully and check antibody titre (RPR, rapid plasma reagin test).

— If the titre is 4 times higher than the mother’s then treat.

• All babies born to mothers with a history of syphilis should be followed up to document a negative RPR.

Infants should definitely be treated if their mothers were:

• not treated or inadequately treated

• treated with a non-penicillin drug

• treated less than 4 weeks prior to delivery.

In practice the adequacy of a mother’s prior treatment can be difficult to establish, and you can rarely be confident the mother has not been reinfected since the last course of treatment. Therefore, under these circumstances it is safer to treat all babies.

Treatment is intravenous benzylpenicillin 50 mg/kg/dose twice a day for 10 days, or intramuscular procaine penicillin 50 mg/kg daily for 10 days.

Related

Pocket Notes on Neonatology 2e