Mother to Baby COVID-19 Transmission Possible Purpose Rare

Transmission of SARS-CoV-2 infection from mother to baby before, during and after childbirth is possible but rare, and mothers should be reassured, say researchers.

The new study, published in the British Medical Journal (BMJ), reported that overall fewer than 2% of babies born to mothers with SARS-CoV-2 infection also tested positive for the virus. The researchers also described how “Maternal factors such as severe COVID-19, death, admission to intensive care unit, and postnatal infection seem to be associated with SARS-CoV-2 positivity in offspring”.

In the study an international research team led by the University of Birmingham’s WHO Collaborating Center for Global Women’s Health set out to assess the rates of SARS-CoV-2 positivity in babies born to mothers with SARS-CoV-2 infection, the timing of mother -to-child transmission and perinatal outcomes, and factors associated with SARS-CoV-2 status in offspring.

Severe Maternal COVID-19 Infection Risk a Risk for Baby

To do this they performed a living systematic review and meta-analysis of major databases, preprint servers, and websites that serve as repositories for COVID-19 studies – including Medline, Embase, Cochrane database, and World Health Organization (WHO) COVID-19 database – between 1 December 2019 and 3 August 2021. Two reviewers independently extracted data and assessed study quality – using the WHO classification to categorize the timing of mother-to-child transmission in utero, intrapartum, early postnatal – with 472 studies (206 cohort studies, 266 case series and case reports; 28,952 mothers, 18,237 babies) being included from 569232 identified articles.

Study lead Shakila Thangaratinam, Professor of Maternal and Perinatal Health at the University of Birmingham, said, “Ours is the first study to use the World Health Organisation’s stringent methods to show that it is possible for the virus to be spread from the mother to baby while in the womb, during labor, and after delivery.”

The researchers found that 1.8% of the 14,271 babies born to mothers with SARS-CoV-2 infection tested positive for the virus – with lower rates of 1% when limited to babies with antenatal or intrapartum exposure to the virus.

They also highlighted how babies were more likely to test positive “when the women have COVID-19 or were diagnosed after childbirth”. Specifically, they found that severe maternal COVID-19 (OR 2.4, 95% CI 1.3 to 4.4), maternal death (OR 14.1, CI 4.1 to 48.0), maternal admission to an intensive care unit (OR 3.5, CI 1.7 to 6.9) , and maternal postnatal infection (OR 5.0, CI 1.2 to 20.1) were associated with SARS-CoV-2 positivity in offspring.

Vaginal Birth, Skin-to-Skin Contact and Breastfeeding Carry Low Risk

Professor Thangaratinam reiterated, “Parents and healthcare professionals can be reassured that only a very small proportion of babies born to mothers with SARS-CoV-2 test positive. This implies that the risks of infection to such babies are rare.”

Although severity of maternal covid-19 infection appeared to be associated with SARS-CoV-2 positivity in offspring, when mothers have SARS-CoV-2 infection the trimester of maternal infection, gestation at birth, mode of delivery, breastfeeding, or mother- baby separation at birth, was not associated with positivity in offspring, the researchers said, with Professor Thangaratinam expressing, “Mothers should also be reassured about the low risk of viral transmission through vaginal birthskin-to-skin contact and breastfeeding – all of which should be encouraged.”

Vaccination in Pregnancy Should Be Further Encouraged

The research team recommends that, since babies born to mothers with severe SARS-CoV-2 are more likely to test positive, they will “need to be tested after birth and monitored closely”.

The authors went on to say how “vaccination in pregnancy should be further encouraged to prevent infection and severe disease in mothers”, with Professor Thangaratinam emphasizing “healthcare professionals and policy makers need to be aware of the expected burden of SARS-CoV-2 positivity in babies, and that they can be infected at any time during pregnancy and delivery”, and how this “highlights the need for appropriate measures to reduce risk of viral transmission in the postnatal period”.

The researchers said that they will analyze new studies as further evidence becomes available and also explore the effects that SARS-CoV-2 variants of concern and vaccination have on newborns.