The Vall d'Hebron University Hospital, together with the Lozano Blesa University Clinical Hospital in Zaragoza, are the only two centers in the State that have participated in the INTERCOVID study, coordinated from the University of Oxford and which concludes that COVID-19 increases the risk of complications during pregnancy for mothers and babies, a greater danger than had been found at the beginning of the pandemic. Therefore, according to the authors, pregnant women should be considered as one of the priority groups when planning preventive initiatives, such as vaccination. The results are published in the journal https://jamanetwork.com/journals/jamapediatrics/fullarticle/2779182 JAMA Pediatrics.The project involved an international team of more than a hundred researchers from 43 hospitals in 18 countries with different levels of financial resources, with the collaboration of more than 2,100 pregnant women. Data from the INTERCOVID study provide detailed comparative information on the effects of SARS-CoV-2 on pregnancy for the first time and show that women with COVID-19 are 50% more likely to have complications during pregnancy, such as premature birth, preeclampsia (hypertension during pregnancy) or admission to the ICU. Although the risk of death also appears to increase due to COVID-19, it should be noted that the number of pregnant women with complications in developed countries is very low.Regarding asymptomatic infected pregnant women, Dr. Nerea Maiz, a specialist in the Obstetrics Service at Vall d'Hebron Hospital and a researcher in the Maternal and Fetal Medicine group at the Vall d'Hebron Research Institute (VHIR), comments that "we have been able to show that the risks to both the newborn and the mother, in asymptomatic infected pregnant women are similar to those of uninfected pregnant women".On the other hand, newborns of infected women appear to be almost three times more likely to have serious medical complications and to have to be admitted to the neonatal ICU, mainly due to the increase in preterm births. This increased risk demonstrates the need for intensive monitoring of pregnant women with COVID-19 and their children to prevent, as far as possible, these complications.Dr. Daniel Orós of the Hospital Clínico Universitario de Zaragoza, adds: "In addition, despite the fact that one in ten newborn mothers who tested positive for the virus also tested positive during the first days after birth, it is important to note that breastfeeding does not appear to be related to this increase in infection. However, cesarean delivery could be associated with an increased risk of having an infected newborn".The quality of information available so far on the effect of COVID-19 on pregnancy was very limited. The INTERCOVID study demonstrates the need to collect large-scale multinational data quickly during a health crisis. The study compared each woman affected by COVID-19 with two uninfected pregnant women who gave birth at the same time in the same hospital. These results are an important step in ensuring the best possible care for mothers and their babies."The next challenge is to examine the long-term effects on mothers and children", concludes Dr. Anna Suy, head of the Obstetrics Section at Vall d'Hebron Hospital and principal investigator of the Maternal and Fetal Medicine group of the VHIR.