A new study published preprint in the non-peer-reviewed journal medRxiv in April 2020 provides a systematic review of maternal and fetal outcomes in pregnancy affected by COVID-19, as well as the risk of vertical transmission of the virus.
Pregnancy with COVID-19 is becoming more common, but the absolute number of cases is still low. This means the extent of involvement is not clear as of now. The current systematic review was aimed at covering all available reports, both published and those awaiting publication, that analyzed the effects of this infection on the mother and the baby.
The immunosuppression and the changes in respiratory dynamics characteristic of pregnancy has led to concerns about the increased risk posed by infection with the novel coronavirus on the mother-infant pair.
To quote one study, “The physiologic and immunologic changes that occur as a normal component of pregnancy can have systemic effects that increase the risk for complications from respiratory infections. Changes in the cardiovascular and respiratory systems, including increased heart rate, stroke volume, oxygen consumption, and decreased lung capacity, as well as the development of immunologic adaptations that allow a mother to tolerate an antigenically distinctive fetus, increase the risk for pregnant women to develop severe respiratory disease.”
Earlier epidemics of flu, SARS (severe acute respiratory syndrome), and MERS (Middle East respiratory syndrome) were associated with a higher risk of maternal illness and death in pregnancy compared with that in non-pregnant women.
How was the study done?
The researchers looked at all available databases up to March 31, 2020, to screen for all articles dealing with this topic. There were 23 studies from various countries, mostly from China, but one each from South Korea, Honduras, and Central America. They covered 172 pregnancies and 162 newborns.
The research focused on maternal health characteristics and the adverse outcomes of pregnancy as the primary outcomes. Neonatal outcomes and the presence of the infection in the newborns were also among these outcomes. The modes of treatment for pregnant women with COVID-19 were also examined.
What did the researchers find?
The study found that of the 172 pregnancies complicated by COVID-19, 162 newborns were delivered by 160 women, including two sets of twins. Twelve pregnancies were ongoing at the end of the relevant study.
In pregnancy complicated by COVID-19, the most common symptoms resembled those with which the generality of patients presented: fever in over half the patients (54%), cough in just over a third (35%), myalgia in 17%, dyspnea in a little over a tenth (12%), and diarrhea (4%).
All the women infected with COVID-19 in pregnancy had pneumonia, as shown by radiological signs on CT scan imaging.
Most of the pregnancies (almost 9/10) ended in delivery by Caesarean section. The reason, in many cases, was not strictly obstetric but related to decisions to prevent potential vertical transmission to the baby in the perinatal period through vaginal secretions. Most babies in some studies were separated from their mothers at birth until the mothers recovered and tested negative for the infection.
What were the complications of COVID-19 in pregnancy?
The complications experienced by these women included:
- Preterm labor in a fifth of cases (21%)
- Fetal distress in a tenth of cases (9%)
- Premature rupture of membranes (8%)
Many women had other conditions as well, such as:
- Diabetes and hypertensive disorders of pregnancy in a tenth (11% and 9% respectively)
- Disorders of the placenta in 5%
- Other infections in 5%
- Uterine scarring in 5%
- Hypothyroidism in 5%
- Anemia in 4%
The babies born to these mothers had the following complications:
- Preterm birth in 23% (compared to 10% of live births)
- Respiratory distress syndrome in 14% (compared to 1.72% of all live births, and 37% of preterm births)
- Pneumonia in 14% (expected rate: 1% and 10% in term and preterm infants, respectively)
- Low birth weight in 11% (compared to 33% of total live births)
- Small for gestational age in 3%
- Stillbirth and neonatal death – one case each.
The number of babies infected by vertical transmission was estimated to be 11%. This is among the earliest confirmations of the existence of vertical transmission in COVID-19, with most earlier studies having found no evidence of this mode of spread.
What does the study show?
In pregnant women with COVID-19, other coexisting illnesses are likely such as diabetes and hypertensive disorders, and the rate of preterm delivery is high. Newborns of these mothers are more likely to suffer from pneumonia and respiratory distress syndrome. Vertical transmission is also likely in over a tenth of these cases.
These figures agree with those of other studies. It is important that some experts feel that severe infection of the mother could increase the frequency of all labor-related complications, including Cesarean for abnormal fetal heart tracings.
It is noteworthy that most of the women were in the third trimester, and all had mild symptoms. The effects of COVID-19 on fetuses whose mothers are infected in the first or second trimesters are unknown. Similarly, the outcomes of babies and mothers with severe infection are far from clear. From the results presented here, it is clear that mothers suspected to have the infection should be screened carefully, and both mothers and babies in confirmed cases require long-term follow-up to assess the outcomes.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
- Gajbhiye R., Modi D., and Mahale, S. Pregnancy outcomes, Newborn complications and Maternal-Fetal Transmission of SARS-CoV-2 in women with COVID-19: A systematic review. medRxiv. doi: https://doi.org/10.1101/2020.04.11.20062356