All neonates born to mothers with positive RT-PCR for 2019-nCoV RNA and hospitalized in the neonatal care unit from April 20 to June 5, 2020, were included. In accordance with the flow of patients infected with COVID-19, all pregnant women admitted at the maternity during the study period benefited from a Reverse-Transcriptase PCR test for the detection of 2019-nCov on nasopharyngeal swabs. Once the positive result was obtained and depending on the clinical condition of the patients, a multidisciplinary staff with gynecologists, pediatricians and anesthesiologists decided on the treatment which included rapid child delivery in case of severe maternal acute respiratory distress syndrome. The patients were isolated in all cases, either in intensive care unit or in maternity ward. All the newborns were managed by a team including a nurse and a pediatrician, wearing full personal protective equipments. After neonatal evaluation and primary care in the delivery room, neonates were admitted and treated in neonatal care unit in a dedicated area. If their clinical condition permitted, they were given an antiseptic bath using CYTEAL® (hexamidine diisetionate, chlorhexidine gluconate and chlorocresol) before installation in an incubator. Routine care was then administered by the nursing staff with the usual infection preventive measures in the neonatal unit. Since the mothers were usually still in isolation, visits to newborns were only permitted through the window of the isolation area. Due to the clinical condition of the mothers, but also because of the difficulty to ensure expression and transport of breast milk under ideal aseptic conditions, all the newborns in our series received infant formula during their hospital stay.

Demographic data, obstetrical history, disease onset, specific COVID-19 treatment protocols, method of delivery and maternal outcome were collected from the files of mothers with 2019-nCoV infection. Information from the neonates including gender, gestational age, birth weight, clinical presentation, laboratory findings, chest X-ray images, treatment on admission and outcome were also collected.

All four mothers were symptomatic with poor general condition, asthenia, fever, cough and severe respiratory distress and had a positive RT-PCR for SARS Co-V2 from nasopharyngeal swab on admission (Table 1 and Table 3). They were aged between 26 and 34 years. The onset of the disease ranged between 7 and 11 days prior to childbirth. All the mothers were managed in the intensive care unit where they received hydroxychloroquine and azithromycin as specific treatment for COVID-19 according to the national therapeutic guidelines (Table 3). They all gave birth through cesarean delivery indicated for persistent severe respiratory distress. Four preterm infants were born. Three mothers recovered from their COVID-19 infection and were discharged healthy. One mother died from severe respiratory distress within 24 hours after surgery (Table 1).

¹APE: Acute Pulmonary Edema. ²SARS: Severe Acute Respiratory Syndrome. ³CS: Cesarean section

Four male infants were born prematurely through cesarean section between 30 weeks and 35 weeks 2 days of pregnancy. The birth weight ranged between 1090 g and 2950 g. All infants had a 1-minute Apgar scores between 7 and 8 and 5-minute Apgar scores varying from 8 to 9 (Table 1). They were isolated from their mothers immediately after birth and received formula feeding. Three of the four infants were tested using a nasopharyngeal swab specimen for RT-PCR 24 to 48 hours after birth and were all negative for COVID-19. One of the newborns had not been tested due to a shortage of tests. Clinically, all the infants presented with respiratory distress on admission in neonatal care unit with a Silverman score that varied between 2 and 4/10. During their hospitalization, all the infants also presented with jaundice and underwent phototherapy. They all had normal white blood cells and platelets. Three had anemia with hemoglobin levels ranging from 105 to 123 g/L requiring for blood transfusion (Table 2 and Table 3). One of the infants (Case n°3) presented a prolonged oxygen dependence and was maintained under oxygen for one month, suggesting mild bronchopulmonary dysplasia. All infants received supportive care with intra venous fluids and oxygen. The time of initiating enteral feeding was between 2 and 3 days (Table 3). None of our patients received a specific COVID-19 therapy (Table 4). The hospital stay varied from 3 to 48 days. Though presenting a mild respiratory distress, one newborn died unexpectedly 3 days after birth. The three others were discharged healthy.

NA: not available.

NA: not available.

The 4 mothers included in our study were young with ages ranging from 26 to 34 years (average age of 30.75 years). Di Mascio et al. in a systematic review on the outcome of coronavirus spectrum infections during pregnancy found an average age of 34.6 years in mothers affected by coronavirus infections [6]. Another systematic review on maternal and perinatal outcomes with COVID-19 in 108 pregnancies found a maternal age ranging between 29 and 32 years which is similar to our findings [7]. The mean time between the onset of symptoms and delivery was 9.5 days in our series, same as 9.4 days found by Liu et al. [8]. All our patients presented a severe form of the disease with severe respiratory distress requiring treatment in intensive care unit. Care to positive COVID-19 patients was given in a dedicated ward of the hospital allowing isolation and with adequate monitoring systems. Regarding the mode of delivery, all our patients underwent cesarean delivery indicated for severe acute maternal respiratory distress syndrome. Other studies on COVID-19 during pregnancy reported a higher rate of cesarean delivery compared to general population, with a rate ranging from 91% to 92% [6] [7], and fetal distress was the most frequent indication for cesarean section [7] [9].

Regarding the newborns, all were male and premature. The gestational age ranged from 30 to 33.8 weeks with a mean of 32.9 weeks. In the Di Mascios’ et al. systematic review, the pooled proportions of preterm birth < 37 and <34 weeks of gestation were 41.1% (14 of 32, 95% CI, 25.6 - 57.6) and 15% (4 of 32, 95% CI, 3.9 - 31.7), respectively [6]. Prematurity with a gestational age of less than 34 weeks of pregnancy seems to represent a low proportion in infants born to COVID-19 positive mothers. In our series, all the children were born prematurely due to the severe clinical condition of the mothers, in whom management of maternal distress required rapid child delivery. The weights of the newborns ranged from 1090 g to 2950 g (12.75 to 87.36 percentile respectively) and one was small-for-gestational age (SGA) [10]. Zhu et al. in their series had 2 small infants for gestational age [10] [11]. Being an acute condition occurring during the third trimester of pregnancy, COVID-19 may have little impact on fetal growth and ultimately, the occurrence of intrauterine growth retardation would be more linked to its usual maternal and fetal causes than to COVID-19. None of our patients was born with an APGAR score less than 7 at 5 minutes. All patients presented with respiratory distress at birth although mothers received corticosteroid for fetal lung maturation. One baby presented prolonged respiratory issues related to a mild bronchopulmonary dysplasia which is not an exceptional clinical presentation in a 30 weeks infant. During hospitalization, all infants developed jaundice and were treated with phototherapy and three patients had severe anemia that required packed red blood cells transfusions. We think this evolution is not specific to COVID-19 but it is a common course in premature infants. One newborn died few days after birth. According to Di Mascio et al. in their systematic review, the pooled proportion of perinatal death was 7% (2 of 41, 95% CI, 1.4 - 16.3) including 1 stillbirth (2.4%) and 1 neonatal death (2.4%) [6].

The four newborns in our series were separated from their mothers immediately after birth and fed with infant formulas. Although strongly supporting breastfeeding, the American Academy of Pediatrics (AAP) and the Center for Disease Control (CDC) recommend temporary separation of newborns from infected mothers, while the World Health Organization (WHO) does not recommend separation of infants from their mothers, but rather encourages skin to skin contact, rooming-in and exclusive breastfeeding [12]. All recommend that mothers who room-in or breastfeed should follow strict hand washing and use of masks. Furthermore, some authors assume that the separation of the mother-infant done at birth and the absence of breastfeeding could be deleterious for the newborn [13]. In our series, considering the severe clinical condition of the mothers, we opted for the separation of the mother-infant dyad at birth and formula feeding of infants born to COVID-19 mothers during their hospital stay. The mothers were reunited with their infant after discharge from the hospital and breastfeeding was introduced without difficulty at home for two infants, while one was taken care of by the aunt and continued formula feeding since the mother died shortly after cesarean delivery.

In order to check whether infants were born infected, we carried out SARS-CoV-2 nucleic acid detection of postnatal throat swab of the newborns. The results showed that all the 3 samples tested were negative, which did not suggest a possible intrauterine transmission. Those results are consistent with other series publications, where no neonates born to COVID-19 mothers were found positive to SARS-CoV-2 at birth [6]. Data suggest that angiotensin-converting enzyme-2 (ACE2) receptors have low expression in the placenta, which makes the chance of SARS-CoV-2 vertical transmission through the placenta unlikely [14]. Some research indicated that SARSCoV-2 nucleic acid in placenta was undetectable [8]. However, it remains unclear if the maternal viral load or timing of SARS-CoV-2 infection may influence the transmission [15].

The main limitation of this study is the small number of newborns included. Follow-up of a larger sample of infants born to mothers infected with 2019-nCoV is necessary for thorough description and analysis of their clinical evolution and 2019-nCoV transmission.