How dangerous is Covid-19 for mother and baby? Here's everything we know

Pregnant women are thought to be no more likely to contract the infection than the general population – but the wider effects of Covid-19 on pregnancy are not yet fully understood, experts warn.

Early reports suggest that women in late-pregnancy with the novel coronavirus are also unlikely to pass the infection on to their baby, however the potential influence of the virus on a fetus’s early development has yet to be studied.

Dr Joy Lawn, a professor of maternal, reproductive and child health at the London School of Tropical Medicine (LSTM), told The Telegraph that we should be wary of Covid-19 and its effect on pregnant women.

“We know that if you’re early in pregnancy there are some infections that have a risk of causing a major abnormality,” she said. “For example, Zika has that effect. And we know that in later pregnancy lots of infections like flu or malaria can cause an increased risk of preterm birth.”

“With Covid-19, obviously we haven’t had anyone who we’ve followed through with early pregnancy so we don’t know if there are early pregnancy effects,” she added.

The rapid spread of Covid-19, which has so far infected more than 1.5 million people and killed more than 89,000 across the globe, has left scientists and medical experts scrambling to keep up.

Research into the novel coronavirus and how it might affect pregnant women is only just underway and it could be months before impacts of the disease are fully understood.

Here's an overview of everything we do know so far – and the key questions left unanswered.

The current advice

At the moment, current guidance published by the Royal College of Obstetricians and Gynecologists (RCOG) states that “pregnant women do not appear more likely to contract the infection than the general population”.

This observation was based on an analysis of 147 women in China where eight per cent had severe disease and one per cent were in critical condition, according to a report by the World Health Organization in late February.

But beyond these findings, additional evidence is thin. Of the little research available in both the Lancet and JAMA medical journals, there have only been around 100 case studies on pregnant women diagnosed with Covid-19 published.

While the outcomes of these studies were generally good and the vast majority of babies were born free of infection, the available research tends to only provide clinical evidence on women in their final trimester who presented symptoms of Covid-19 while under hospital care and who delivered their baby under expert supervision.

Vertical transmission – when the baby becomes infected while in the uterus – is still unconfirmed and no one has yet been able to study the impact of infection on early pregnancy.

Understanding the full extent of the disease is difficult. In the months since Covid-19 first emerged, few cases of pregnant women falling ill with the virus have been reported – a problem that is especially true in the UK, where so far only those admitted to critical care have been tested for the disease.

On March 16, 2020, the Government placed pregnant women in the “at risk group”, alongside people who are over 70 and those who have an underlying health condition.

The changes to the UK’s advice were described as "a precautionary measure" by chief medical officer Chris Whitty, who then strongly advised pregnant women to practice social distancing for the next 12 weeks in order to limit the risk of exposure to infection.

According to the guidance published by the RCOG, the new measures rely on prior knowledge which shows that, “whilst pregnant women are not necessarily more susceptible to viral illness, changes to their immune system in pregnancy can be associated with more severe symptoms.”

Only one out of every six people appear to become seriously ill and develop difficulty breathing, the WHO estimates. However, naturally low immunity during pregnancy may mean expectant mothers could be disproportionately represented in this category.

“Unfortunately it’s a wait and see,” explains Dr Marian Knight, professor of maternal and child population health at the National Perinatal Epidemiology Unit and programme lead of MBRRACE-UK, the national enquiries into maternal morbidity and mortality.

“Most women who are pregnant in the UK are in their late 20s to early 30s and what we know about those in their 20s to 30s who have had Covid-19, [is that] they don't seem to be severely affected.

“But adopting a precautionary principle to this disease seems very sensible to me. We’re basing it on prior knowledge of other viruses and other diseases and what we know about pregnancy.” she added.

What past epidemics can tell us

One of the biggest worries healthcare professionals have to contend with is the potential for increased risk of maternal mortality.

Previous epidemics of many emerging infections have typically resulted in poor obstetric outcomes, including maternal morbidity and mortality, contagion from mothers to newborns, and perinatal infections and death.

Between 30 and 50 per cent of pregnant women were thought to have died during the 1918 and 1957 flu pandemics.

One small study of 12 pregnant women who developed Sars during the 2003 outbreak – which infected more than 8,000 people across 26 countries and killed 774 – reported three deaths while four of the seven women who were in their first trimester experienced a spontaneous miscarriage.

Another data set of 11 pregnant women studied during the Mers outbreak – which was first reported from Saudi Arabia in 2012 – showed similar adverse outcomes.

And during the H1N1 Swine flu pandemic of 2009, pregnant women were around four times more likely to be hospitalised for complications from flu, compared to the non-pregnant population.

There’s no doubt that previous outbreaks are playing on many expectant mother and doctor’s minds. However, Dr Knight is keen to point out that we don’t yet know if Covid-19 will impact pregnancy in the same way previous coronavirus outbreaks have.

“In terms of maternal deaths there is no evidence to suggest that women who are pregnant are more severely affected than women who are not pregnant. It is unlikely that we will see an increase in maternal deaths. But it’s always hard to know.”

The outcomes of other coronavirus infections may suggest that pregnant women could be more at risk, but that doesn’t mean we can or should compare viruses, agrees vice president of RCOG Dr Patrick O’Brien who is currently leading the national guidance.

“I don't think we can confidently extrapolate from other coronavirus infections into this one. For example, if you look at the death rate in Mers in adults it was much higher. If you look at Swine flu (H1N1), it was very clear that infection was much worse in pregnant women.”

“Everything we have seen so far suggests that [Covid-19] is no worse… We reserve the right to update that as [more evidence] becomes available,” he added.

In the face of the evolving pandemic, the RCOG has made appropriate changes to care as well as regular updates to the advice for pregnant women.

And in March, a study led by Dr Marian Knight to determine the outcomes of Covid-19 in pregnancy for mother and infant was launched by the UK Obstetric Surveillance System (UKOSS).

But, until those results of published, it ultimately pays to be cautious, says Dr Knight: “The measures are to stop pregnant women from getting an infection and if you don't get an infection, then obviously none of this is going to be a worry to you.”

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