Can Covid-19 be transmitted to the baby in utero? Researchers from all over the world are trying to answer this question and are fighting over the probabilities. The latest study published on this subject suggests that it is possible. Let's take stock of the situation.
A newborn baby tested positive for Covid-19 in the UK. His mother had been admitted to North Middlesex Hospital near London a few days before delivery for pneumonia, but it is not known if the virus was transmitted to the baby in utero or after birth.
Can a mother pass the virus to her baby during pregnancy?
While opinions differ on this, a recent study published in the journal Jama Pediatrics suggests that it is possible. Chinese researchers followed 33 pregnant women infected with covid-19 at the Wuhan Children's Hospital in Wuhan, China, where the epidemic broke out. Three male babies were delivered by Caesarean section and tested positive the day after birth. "The most common symptom was shortness of breath and affected 4 of the 33 newborns," the researchers said.
Symptoms on a case-by-case basis
The first baby to test positive was born at 40 weeks of pregnancy. The delivery was performed by caesarean section due to meconium-filled amniotic fluid (excrement accumulated in the fetus' intestines) and maternal pneumonia due to Covid-19. The next day, the infant suffered from lethargy (severe fatigue) and fever and was transferred to the neonatal intensive care unit. The baby suffered from pneumonia: "Nasopharyngeal and anal swabs were positive for SARS-CoV-2 on days 2 and 4 of the baby's life and negative on day 6".
The second baby was born at 40 weeks and 4 days gestation and by Caesarean section, also due to maternal pneumonia caused by Covid-19. He presented with lethargy, vomiting and fever. Tests showed leukocytosis (an abnormal increase in the number of white blood cells in the blood), lymphocytopenia (indicating a decrease in lymphocytes) and a high level of creatine kinase (an enzyme found in muscles). He also had pneumonia and like the first, "nasopharyngeal and anal swabs were positive for SARS-CoV-2 on days 2 and 4 of life and negative on day 6.
Finally, the third baby was born prematurely at 31 weeks due to fetal distress (a decrease in oxygenation). He was born by caesarean section also because of maternal pneumonia due to the virus and required resuscitation. He suffered from "respiratory distress and pneumonia confirmed by a chest X-ray, which were cured on day 14 of life after treatment with non-invasive ventilation, caffeine and antibiotics," write the researchers.
"Since strict infection control and prevention procedures were in place during delivery, it is likely that the sources of SARS-CoV-2 in the upper respiratory tract or anus of newborns were maternal in origin," the researchers concluded. However, probability is not certainty and many experts have reacted to this publication on Science Media Center.
A study considered inconclusive by many experts
Dr. Pat O'Brien, consultant obstetrician and vice-president of the Royal College of Obstetricians and Gynaecologists (UK), says, "This study cannot confirm how the three babies contracted the virus and we note that the first test for all three babies was not performed until the second day of life, increasing the possibility that infection occurred after birth. Nevertheless, he concedes, it is possible that an infection may have occurred in utero, but this study is not conclusive".
Dr. Erica Watson, senior lecturer in reproductive biology at the University of Cambridge (UK), recalls that "several other studies have ruled out the transmission of Covid-19 in the uterus, one of which found that the umbilical cord blood (the baby's blood) and amniotic fluid (the fluid that surrounds the baby in the uterus) tested negative. Based on the evidence available to date, it is unlikely that Covid-19 can be contracted in the uterus and therefore it is unlikely that babies will be born with the infection".
A view that is also shared by Dr Elizabeth Whittaker, consultant in Pediatric Infectious Diseases at St Marys Paddington Hospital: "There is still no conclusive evidence that the virus can be contracted in the womb and it is more likely that infants were exposed during delivery or immediately afterwards".
However, she said, "this study provides reassuring information for pregnant women who will deliver during the pandemic," particularly because "two of the three babies were born at term and developed mild symptoms that disappeared within a few days without requiring significant medical intervention. The third was born prematurely and although he tested positive, he followed the clinical course expected for most infants born at 31 weeks' gestation with good results".
A bad time to get pregnant?
In one of our broadcasts, Professor Jean-Michel Ayoubi, head of the obstetrics and gynecology department at the Foch Hospital in Suresnes, also confirmed that no scientific data to date has been able to establish a link of transmission in utero. "A few publications mention the risk of premature delivery or the possibility of malformation in the first trimester, but this is patchy information based on a few experiments here and there," he deplored.
Nevertheless, as the probability remains uncertain, he recommended that women who tested positive should avoid becoming pregnant. "It is indeed favorite that a woman positive to the Covid-19 test, during a given period of time, avoids a possible pregnancy. As you know, the Agence de biomedicine and PMA centers in France have stopped medically assisted procreation until further notice" as a precautionary measure.
