Congenital CMV: the damage follows first-trimester infection

Design

prospective observational cohort study at a single tertiary referral centre, 2001-2024, with centralised serological dating and standardised follow-up to 48 months

Population

642 children with confirmed congenital cytomegalovirus infection; 504 with dated maternal primary infection (288 first-trimester, 144 second, 72 third)

Primary outcome

hearing loss, neurodevelopmental impairment and autism spectrum disorder by timing of maternal infection

Effect

long-term sequelae only after first-trimester infection; autism in 11 children (1.7%), odds ratio 4.25 (95% CI 1.63-21.33) versus population estimate; temporal lobe white matter abnormality in all autism cases

Congenital cytomegalovirus is the leading non-genetic cause of sensorineural hearing loss, and counselling has been hampered by imprecision about when in pregnancy the risk is concentrated. This prospective cohort followed 642 children with confirmed congenital infection at a single French tertiary centre between 2001 and 2024, with maternal infection dated by centralised serology and standardised follow-up to 48 months.

Of 504 children whose maternal primary infection could be dated, 288 followed first-trimester infection, 144 second-trimester and 72 third-trimester. Long-term sequelae — hearing loss and neurodevelopmental impairment — were observed exclusively after first-trimester exposure. Autism spectrum disorder was diagnosed in 11 children (1.7%), all symptomatic at birth, and all cases following maternal primary infection came after first-trimester exposure; prevalence was about four times the French population estimate (OR 4.25, 95% CI 1.63-21.33). Every child diagnosed with autism had temporal lobe white matter abnormality on postnatal MRI, present antenatally where fetal MRI had been done, and no child without that finding developed autism.

The imaging correlate is striking and the cohort is large and prospective, but 11 cases cannot support a screening rule and a single referral centre sees a selected population. Read it as two usable things: a woman with confirmed second- or third-trimester primary infection can be counselled far more reassuringly than the older literature allowed, and temporal lobe white matter change on fetal or neonatal imaging is a finding to look for and to follow, not an incidental note.

• Date the maternal infection: it is the single most useful prognostic variable
• Counsel second- and third-trimester primary infection much more reassuringly than first-trimester
• Look specifically at the temporal poles on fetal and neonatal MRI
• Autism was confined to children symptomatic at birth — asymptomatic infection carried no cases here
• This is one tertiary centre and 11 autism cases; do not convert it into a screening protocol

The statistics, in plain English

An odds ratio of 4.25 with an interval from 1.63 to 21.33 is driven by 11 cases; the upper limit shows how little precision that allows, and the comparison is against a general-population estimate rather than a matched control group. 'Exclusively after first-trimester exposure' means no events were seen in the later-trimester groups, which had 144 and 72 children — with those numbers, a low but real rate could easily have been missed. That every autism case had a temporal lobe abnormality is a strong internal association, but it is derived and tested in the same cohort, so it needs independent replication before being used prospectively.

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