Management of cytomegalovirus infection in pregnancy

M R C O G PA R T 2 · S O S P O C K E T C A R D · K N O W L E D G E A R E A 5 – A N T E N ATA L C A R E

Management of Cytomegalovirus Infection in Pregnancy Kalogeropoulou M-S, Beardsall K, Andersson M, Ioannou C. Management of cytomegalovirus infection in pregnancy. TOG 2025;27:207–218. doi:10.1111/tog.12987

0.48% 8 g/day 71% CCMV PREVALENCE, HIGH-INCOME COUNTRIES VALACICLOVIR DOSE (2 G/6 H) REDUCTION IN VERTICAL TRANSMISSION

DO N' T-M IS S FA C TS

1. Take an index sample (IgM + IgG) after reported exposure; if both negative repeat at 4 weeks. Always test the stored booking sample (IgM, IgG, avidity) when index IgM is positive

2. AI <30% = infection <3 months ago; AI >60% = >3 months ago (likely preconceptual, cautiously reassure)

3. Valaciclovir 8 g/day (2 g/6 h) for primary infection in first half of pregnancy → 71% reduction in vertical transmission; stop after negative amniocentesis at 21–22 weeks; monitor renal function (1.7% acute renal failure)

4. Amniocentesis timing: >7 weeks post-infection AND >21 weeks. Miscarriage risk 0.30%; third-trimester preterm birth risk 1.2%. Still 3–8% CMV positive at birth despite negative amniocentesis

5. Confirmed fetal CMV: ultrasound every 2–4 weeks + fetal brain MRI 28–32 weeks. Normal both = reassuring but 17% residual SNHL risk

6. Termination: ground C before 24 weeks; ground E at any gestation with severe ultrasound abnormalities + positive amniocentesis (MDT review)

7. Neonate: saliva/urine CMV PCR within 3 weeks of birth; valganciclovir 6 mg/kg BD within the first month of life

8. Breastfeeding is safe and recommended in cCMV; but up to 20% of preterm/VLBW infants acquire postnatal CMV via breast milk — consider pasteurisation. Wait ≥1 year before next pregnancy after an affected baby

RED FLAGS ON SCAN — THINK CMV

FGR <3rd centile Hydrops / ascites Brain abnormalities Liver calcifications

Isolated polyhydramnios — no CMV serology Isolated echogenic bowel — only 1.4% cCMV

NUMBERS TO KNOW

cCMV prevalence 0.48% high-income (1 in 200 live births); 1.42% low/middle-income UK CMV IgG seroprevalence 49%; in pregnancy 50–60%; seroconversion 1–7%/year Transmission: 25–45% / 45% / 47–78% by trimester; non-primary 1.4%; primary risk 4× higher 10–15% symptomatic at birth; mortality 5%; 8–18% of asymptomatic develop sequelae; 7 in 10 normal neurodevelopment Fetal MRI: temporal ↑T2 signal 14% SNHL; temporal/occipital cysts 25%; migrational disorder/cerebellar hypoplasia 67% UK cost £732 million/year; only 33% of UK women aware of CMV

DON'T SAY ‘TORCH SCREEN’

Blanket term for heterogeneous pathogens; ‘negative TORCH screen’ hides which pathogens were tested and the IgG/IgM profile. Specify the test and result. Universal CMV screening not recommended in the UK; review serology jointly with a virologist/microbiologist. ABBREVIATION KEY

CMV — cytomegalovirus MRI — magnetic resonance imaging

cCMV — congenital cytomegalovirus CNS — central nervous system

SNHL — sensorineural hearing loss NPV / PPV — negative / positive predictive value

AI — avidity index TORCH — toxoplasmosis, rubella, cytomegalovirus, herpes

PCR — polymerase chain reaction ISUOG — International Society of Ultrasound in Obstetrics and Gynaecology IgG / IgM — immunoglobulin G / immunoglobulin M MDT — multidisciplinary team HHV-5 — human herpesvirus 5 IV — intravenous

Source: The Obstetrician & Gynaecologist (TOG), RCOG journal — 2025;27:207–218. doi:10.1111/tog.12987

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