The COVID-19 pandemic shows no sign of being over, in many parts of the world, posing a continuing source of infection to those countries and regions where a measure of control has been achieved. One big concern has been the effect of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on pregnancy, including the increased risk of complications during this time, and the possibility of vertical transmission from the infected mother to the fetus or infant.
Differential Involvement in Pregnancy
The earlier SARS epidemic caused by another betacoronavirus was associated with severe disease and high mortality in pregnant women and a higher risk of miscarriage. The MERS epidemic similarly caused poor clinical outcomes when the infection occurred in pregnancy. The association of a high case fatality rate with certain clinical or demographic features in COVID-19 patients, such as advanced age or cardiovascular risk factors, led researchers to examine whether pregnancy was also a high-risk group for this viral illness.
Earlier reports have stated that most women infected in pregnancy have mild illness and maternal mortality is low. However, postpartum complications are slightly higher in this group compared to non-pregnant infected women. Two papers reported a remarkable reduction in very preterm births (less than 28 weeks gestational age) to uninfected women after the pandemic began, but higher rates of preterm birth by Cesarean section to infected women. However, there is no suggestion that these Cesarean interventions were because of the illness, but rather it would seem that the presence of the infection prompted them.
Evidence of newborn infection has been gathered, where following a Cesarean delivery, with the baby immediately isolated from the mother and not breastfed, viral RNA was detected. Transplacental transmission has been documented in one case, where viral RNA was found in umbilical cord blood, blood samples collected from the newborn within the first 12 hours of life, or amniotic fluid collected before the membranes ruptured. Placental thrombi have been detected at a higher rate in infected pregnancies and might indicate the possibility of impaired fetal development even without a fetal infection.
Following Women Through Pregnancy
The Mother and Child Covid-19 (MOACC-19) study is a cohort recruiting approximately 1,000 pregnant women in Northern Spain, in the region called Cantabria. It includes three subgroups. The first comprises women who gave birth between March 23 and May 25, 2020. This subcohort is therefore retrospectively recruited, and COVID-19 could have been acquired only in the third trimester.
The second and third subcohorts include women who gave or will be giving birth from May 26, 2020, and those who are at the 12th week of pregnancy, recruited from May 26 onwards. The former may have been infected in either the second and third trimesters, and at any time during pregnancy, respectively.
Almost half of the women were 35 or older, and 86% were European. About 55% had studied less than up to the university level, and 70% were working. About half of the pregnancies were to first-time mothers. About a fifth of the deliveries so far was by Cesarean or other interventions.
All these women are tested for COVID-19 by reverse transcriptase-polymerase chain reaction (RT PCR) to detect viral RNA and enzyme-linked immunosorbent assay (ELISA) for specific anti-SARS-CoV-2 antibodies. The newborn infants are also tested for antibodies using immunochemoluminescence tests. If the mother is COVID-19 positive, a swab is taken from the infant for RT PCR. Children will undergo follow-up for a year to identify any effects of the illness on their normal development.
No Infected Newborns So Far
The researchers say that they have met about half of their recruiting capacity, with over 200, 130, and 130 participants in the first, second, and third subgroups. As of now, they say 8 women have been found to be positive for the virus, 6 being from the first, and one each from the other two subgroups. Only one had symptoms of respiratory difficulty but normally delivered at 39 weeks. Another woman reported the presence of nausea but is currently still pregnant.
Two of the 8 women had contact with a COVID-19 case at home, but the others had no known contacts with infected individuals. Of the 344 children born so far, 7 children have been born from these infected women. None of the infants were found to be positive. One required intensive care unit admission due to respiratory distress, with a low Apgar score at 1 minute.
Advantages of the Study
This study has some issues, such as being possibly underpowered in a country with a 5% prevalence of COVID-19; the researchers say they will enlarge the study if this is shown to occur. However, it is taking place in a developed country affected early and severely in the course of the pandemic, in women at all periods of gestation, and in a country with universal public health care. The hospital setting ensures homogeneous health care and data recovery.
The results from this study may later be integrated with the International Registry of Coronavirus Exposure in Pregnancy (IRCEP, https://corona.pregistry.com), allowing comparisons to be made between this cohort and those in other places.
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