One of the most concerning issues regarding COVID-19 is how the virus affects pregnant women and their unborn children. Even if research is still limited, the so far published studies seem to be reassuring, suggesting that mother-to-child transmission is unlikely for this virus.
Symptoms of COVID-19 infection in pregnant women
Pregnant women infected with the virus seem to have the same symptoms as non-pregnant women. In a systematic review including 33 studies and 385 pregnant women with COVID-19 infection, the most frequent symptoms were fever (67.3%), cough (65.7%), dyspnea, i.e shortness of breath (7.3%), diarrhea (7.3%), sore throat (7.0%), fatigue (7.0%), myalgia, i.e muscle pain (6.2%), and chills (5.5%). Infection was asymptomatic in 7.5% women. Among the symptomatic ones, 95.6% had mild symptoms, 3.6% severe; and 0.8% critical symptoms (1).
Diagnosis is made mainly based on RT-PCR and the specimen is collected using nasopharyngeal swabs (sample of nasal secretion from the back of the nose and throat). Additional specimens can be collected in the form of nasal swab, vaginal swab, urine, stool, and sputum. Clinical and radiological features are also used for the diagnosis. Furthermore, to avoid exposing pregnant women to radiation, it has been reported the successful use of lung ultrasound to diagnose pneumonia in pregnant women with COVID-19 (2). Laboratory findings include elevated levels of some proteins in the blood like D-dimer, C-reactive protein and modest increase in liver enzymes, as well as lymphopenia (low levels of one of the white blood cells type with important functions in the immune system) and thrombocytopenia (low levels of platelets in the blood) (1).
The admission to intensive care unit (ICU) was required in 4.4% of women in the review by Elshafeey et al, while 1.6% of them were mechanically ventilated . All ICU admissions improved and were discharged, except for one death (1). Mullins et al report that among 32 pregnant women, 2 of them required intensive care unit (ICU) admission. There were no maternal deaths (3).
Pregnancy outcomes and type of delivery
In a systematic review and meta-analysis by Di Mascio et al the most common adverse pregnancy outcome among women with COVID-19 was preterm birth (<37 weeks of gestation) (41.1%). However, it was not mentioned if the preterm births were attributed to COVID-19 or not (4). Among 48 pregnant women with COVID-19, analysed in another review, preterm birth was observed in 39.6% and low-birth weight in 27% of cases. In 10.5% of cases the preterm birth was due to spontaneous preterm labor (5). Among 385 women included in the review by Elshafeey et al, the course of pregnancy included birth in 65.5%, ongoing pregnancy in 32.2%, induced abortion in 1.0%, spontaneous abortion in 0.8%. In another review, preterm birth occurred in 15.2% of newborns and low birth weight (<2500 g) was reported in 7.8% of newborns. Among women who gave birth, 30.6% had a vaginal delivery (1). In another review that included 13 studies and 64 women who delivered, vaginal delivery was reported in only 9.4% of cases (5).
Since most deliveries among pregnant women with COVID-19 infection have occurred through a Cesarean section, there is less information on vaginal delivery.
The indication for performing a Cesarean section was in most cases the worsening of women’s conditions. The surgery should be performed in a negative-pressure operating room (air enters the room freely, but only exits through a filtered ventilation system in order to prevent spread of infection outside the room) after taking all the necessary measures to prevent any infection.
Risk of transmission in newborns and neonatal outcomes
The review by Parazzini et al reports that, in a sample of 64 pregnant women, two newborns tested positive for SARS-CoV-2 by real-time RT-PCR (5). In the review by Elshafeey et al, among 385 studied cases, 1.6% of newborns, delivered by Cesarean section had positive RT-PCR test results and were classified as mild cases. Samples from cord blood and amniotic fluid were negative. All of them recovered and were discharged (1). Di Mascio et al, report in a systematic review and meta-analysis that no case of vertical transmission (transmission of the virus to the baby while in the womb) was found among 6 studies including 41 pregnant women (4).
COVID-19 and breastfeeding
Very few reported cases have provided information on the risk of newborn infection through breast milk. However, the fact that all samples of breast milk from 26 women tested negative for COVID-19, as reported in the review by Elshafeey et al (1), is probably reassuring for nursing mothers. Guidelines suggest allowing breastfeeding for infected women who wear masks. Preliminary data suggest that the virus is not found in milk.
COVID-19 infection during pregnancy seems to have a clinical presentation and severity resembling the ones in non-pregnant women. The most common adverse pregnancy outcome seems to be preterm birth. The studies published so far suggest that mother-to-child transmission of SARS-CoV-2 is unlikely. The effective implementation of protection measures during delivery, including a negative-pressure delivery room, may help prevent the infant from acquiring SARS-CoV-2 infection.
However, evidence regarding this topic is accumulating rapidly, so these data may need to be updated soon.