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Pediatr Integral 2026; XXX (4): 278
L. Navarro Montilla, I. Fernández Castiella
Residentes de Pediatría del Hospital Universitario La Paz. Madrid
47. Neonatal perinatal herpes prevention
Resident (R): Dr. Collins, could I ask you a question about a newborn I just examined?
Attending (A): Sure, tell me.
R: The newborn is a 40-week-old baby girl who is now 10 hours old. The pregnancy follow-ups showed normal ultrasounds and normal lab studies. She arrived at the emergency service fully dilated and with active uterine dynamics. The baby ended up being delivered in the obstetric emergency service. When I was talking to the mother, she mentioned she had some genital lesions 3 weeks ago and had attended another hospital, where they gave her some tablets and took a sample of the genital lesions.
A: It could be a case of genital herpes.
R: I thought so. I talked with the obstetric team; they didn’t find any active genital lesions in the mother, but we confirmed that she was taking acyclovir. She denied a history of previous genital herpes.
A: Was the newborn’s exam normal? Did you notice any skin lesions?
R: It was strictly normal.
A: Alright. It looks like a primary genital herpes episode quite close to the time of birth. To prevent perinatal infection, a C-section is typically recommended. Let’s review this topic then: genital herpes lesions close to the time of birth. First of all, what do we consider “close to birth”?
R: I looked it up and found that it’s important to ask if the lesions appeared in the last 6 weeks of pregnancy.
A: That is correct. This is because it is the time needed for the mother to develop antibodies; type-specific IgG antibodies cross the placental barrier and protect the newborn against a potential infection. Do you know what tests we should run to rule out an infection?
R: I guess we should do an HSV PCR in blood and cerebrospinal fluid.
A: Yes, we should also take swabs from the nasopharynx, oral cavity, conjunctiva, and rectum for a herpes PCR.
R: Also, we should look for abnormalities in the cerebrospinal fluid biochemistry. I will run a blood test that includes transaminase analysis.
A: We must be vigilant for any lesions that appear on the newborn’s skin. We will start empiric intravenous acyclovir treatment at a dose of 60 mg/kg/day divided into 3 doses. If all lab results are normal we can suspend it in 10 days.
R: I still have a question. I understand that if the mother had a previous history of genital herpes, none of this would have been necessary.
A: Excellent question. You see, there are two serotypes of herpes: HSV-1 and HSV-2. If a mother has specific antibodies against type 1, she can still have a non-primary episode. This means she can be infected late in pregnancy by the other serotype. The risk for perinatal herpes in this case is still high.
R: So any newborn of a mother with a history of lesions compatible with genital herpes before delivery will need preventive treatment and lab studies?
A: There is one exception. If the lesions appeared weeks before delivery, we might have enough time to do a PCR of the skin sample. In this case, we would be able to prove that the lesions were in fact produced by the same serotype for which the mother already had antibodies.
R: I understand. I will go and inform the family and get everything ready to admit the baby to our unit.
KEY WORDS
Active uterine dynamics: dinámica uterina activa.
Primary genital herpes episode: episodio primario de herpes genital.
Non-primary episode: episodio no primario.
Placental barrier: barrera placentaria.
Swabs: frotis.
HSV PCR (Polymerase Chain Reaction): PCR para VHS (reacción en cadena de la polimerasa).
Papulosquamous disorders. Psoriasis