What can deliberately infecting healthy people tell us about infectious diseases? How is this useful for developing treatments, and how do we manage the risks?
- Pregnant women are not more likely to contract COVID-19 than the general population. If they do get the infection, it is likely to be mild or moderate in severity.
- Pregnant women have the same risk factors for COVID-19 infection as the general population. These are age, pre-existing medical conditions, being overweight or obese, or having an ethnic minority background.
- A small proportion of babies born to infected mothers will develop an infection; these babies are not at increased risk of severe disease. Severe COVID-19 infection in newborns is rare.
- A UK study reported that almost all newborns with COVID-19 made a full recovery.
- There is evidence from the UK that babies from a Black, Asian or other ethnic minority group are more likely to be hospitalised with COVID-19 than babies from a White background.
- There is some evidence that maternal COVID-19 is linked to an increased risk of preterm birth and caesarean section.
- Direct transmission of the virus from mothers to babies during pregnancy and birth is uncommon.
- It is unlikely that the virus is transmitted through breastmilk, but large studies are needed to draw firm conclusions.
- This article will be updated as the research progresses.
There is a growing body of research on whether pregnant women are at greater risk from COVID-19 and if they pass the SARS-CoV-2 virus to their babies during pregnancy, birth and/or breastfeeding. Other data describe the outcomes for newborn babies infected with SARS-CoV-2.
This article discusses the latest evidence on how COVID-19 affects pregnant women and what the outcomes are for their babies in the first few weeks after birth. High quality data from UK programmes that monitor the health of pregnant women and their babies allows researchers to measure the impact of COVID-19 and make meaningful comparisons with pregnant women who are not infected.
COVID-19 and pregnancy
The Royal College of Obstetricians and Gynaecologists has published an evidence review covering all aspects of COVID-19 and pregnancy, with other resources written for pregnant women and their families. Overall, pregnant women with COVID-19 are not at higher risk of becoming seriously ill or dying compared with non-pregnant women. Most pregnant women experience only a mild or moderate illness. Research shows that pregnant women have the same COVID-19 risk factors as the general population. These are age and existing health conditions including diabetes, asthma, high blood pressure and being overweight or obese. Being from a Black or other ethnic minority background is also a risk factor for more severe COVID-19 in pregnant women.
The UK has a real-time national surveillance program of pregnant women called the UK Obstetric Surveillance System. This programme tracks pregnant women with COVID-19 throughout their pregnancy and birth. The largest study on outcomes for pregnant women and their babies was reported in two studies by the University of Oxford using data from this surveillance program.
In a study that has not yet been peer reviewed, researchers undertook a study of all hospitalised pregnant women who tested positive for SARS-CoV-2 between March and August 2020. From a total of 1,148 pregnant women with COVID-19, the key findings were:
- 64% of women admitted to hospital who tested positive for SARS-CoV-2 did not have COVID-19 symptoms.
- Most of the women were admitted in later stages of their pregnancy.
- Compared with hospitalised pregnant women without COVID-19, the women in the study were more likely to have the following risk factors: 33% were overweight or obese; 22% had pre-existing health conditions; and 55% were from a Black, Asian or other minority ethnic background.
- Most women did not experience severe complications related to COVID-19.
- Women with symptomatic COVID-19 were more likely to be admitted to intensive care than asymptomatic women.
- There was an increased likelihood of delivering by a caesarean section for women with COVID-19 irrespective of whether they had symptoms, compared with pregnant women without COVID-19.
- There was an increased risk for a baby to be born early based on clinical decisions to intervene (and not due to spontaneous preterm births). One in five babies were pre-term, most of whom needed neonatal care.
The main limitation of this study is that is only looks at hospitalised women; there is no analysis of outcomes for pregnant women with COVID-19 who were not admitted to hospital. Another scientific review analysed results from multiple studies. It also reported the same risk factors for developing severe COVID-19 and an increased risk of pre-term birth for women with COVID-19.
COVID-19 vaccines in pregnancy
UK Government advice currently includes pregnant women on the list of people at moderate risk, as a precaution. Additional guidance advises women to observe social distancing in the last trimester of pregnancy (from 28 weeks).
The Joint Committee on Vaccination and Immunisation, which advises the UK Government, does not recommend routine use of COVID-19 vaccines for pregnant women. However, women with other risk factors that make them clinically extremely vulnerable should consider having the vaccine, based on a discussion of the risks and benefits with a health professional.
COVID-19 and newborns
Evidence so far suggests it is very unlikely that the SARS-CoV-2 virus causes problems with a baby’s development or increases the risk of miscarriage.
A systematic review of multiple studies reported that, overall, most babies (over 95%) born to women with COVID-19 are born in good condition. A range of studies report that SARS-CoV-2 infection is uncommon in newborns, with infections generally mild or asymptomatic. Overall, babies born to mothers with SARS-CoV-2 infection prior to birth are unlikely to need neonatal care, but there are some data that being aged under 1 month and prematurity are risk factors for admission to intensive neonatal care, described next.
In a UK study, researchers examined the incidence of infection and the characteristics and outcomes for babies with SARS-CoV-2 infections in the first 28 days of life. They reported that neonatal SARS-CoV-2 is uncommon in babies admitted to hospital. They analysed data on babies with SARS-CoV-2 infections in hospital between March and April 2020 – at that time 1 in 1,785 babies had an infection, or 0.06% of births. Of 66 babies that tested positive for SARS-CoV-2, 28 had a severe neonatal SARS-CoV-2 infection. This means that that at the peak of the first wave in March to April 2020, 5.6 babies in 10,000 had SARS-CoV-2. The incidence of infection was higher in babies from Black, Asian, mixed or other ethnic groups compared with babies from White ethnic groups:
- White: 4.6 babies per 10,000 livebirths
- Asian: 15.2 per 10,000 livebirths
- Black: 18 per 10,000 livebirths
- Mixed or other ethnic groups: 5.6 per 10,000 livebirths
17 babies were through to have caught the virus from their mother in the first week after birth. Six babies were thought to have acquired the infection in hospital. It was thought possible that two babies acquired the infection directly from the mother either immediately before or after birth. By the time the research study ended, 58 babies had been discharged from hospital, seven remained in hospital and one had died from a cause unrelated to COVID-19.
There is continued uncertainty about direct transmission from mother to baby (called vertical transmission). There is some evidence that shows that a few babies had IgM antibodies to the virus in blood taken from the umbilical cord shortly after birth (IgM antibodies are the first to be made by the body in response to an infection and do not cross the placenta).
No virus was detected in these babies in subsequent testing and they did not have any symptoms. Direct transmission of the virus from mother to baby before or during birth is thought to be uncommon. Considering other research that shows that transmission of the virus from a mother to her baby is low, separating infected mothers from their babies is not supported by evidence.
COVID-19 and breastfeeding
Evidence on the presence of the virus in breastmilk comes from several studies. Many studies report that no virus can be detected in an infected mother’s milk. There are two reports of evidence of SARS-CoV-2 genetic material in breast milk, but it is not clear if there was any virus present that could cause an infection, or if it was the source of an infection in one infant who tested positive. The main risk is the transfer of respiratory droplets containing the virus from mother to baby during breastfeeding. However, the consensus advice is that the benefits of breastfeeding outweigh any potential risks.
The Royal College of Paediatrics and Child Health has published an evidence summary of various aspects of COVID-19 and children which is updated regularly.
COVID-19 in Children, UK Research and Innovation
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