Are pregnant women seven times more likely to die if they get Covid-19?

Question

Accompanying a video on MSN News today (17th jan 023) is the following statement :

Pregnant women who catch Covid are SEVEN times more likely to die, warns new research. They are also at a "significantly elevated" risk of being admitted to intensive care and 23 times more likely to develop pneumonia, according to the study published in BMJ Global Health. In addition, the findings suggest that Covid during pregnancy also increases the risk that the baby will need to be admitted to intensive care. Scientists say their findings add urgency to calls for more women of childbearing age to get vaccinated Lead author Professor Emily Smith, of the George Washington University Milken Institute School of Public Health in the US said: “This study provides the most comprehensive evidence to date suggesting that Covid-19 is a threat during pregnancy.

The only recent BMJ Global Health study I can find on the subject does not make any such claim (that I can find) and states :

Taken together, this analysis of 12 studies including 13 136 pregnant women from 12 countries indicates that SARS-CoV-2 infection at any time during pregnancy increases the risk of maternal mortality, severe maternal morbidities and adverse newborn outcomes. These findings underscore the need for global efforts to prevent COVID-19 during pregnancy through targeted administration of vaccines and non-pharmaceutical interventions.

Is this 'seven times' morbidity claim true ?

Answer 1

An estimate of being roughly seven times more likely to die is a reasonable summary of the information in the paper you linked yourself. The sentence in the abstract is

Pregnant women with SARS-CoV-2 infection—as compared with uninfected pregnant women—were at significantly increased risk of maternal mortality (10 studies; n=1490; RR 7.68, 95% CI 1.70 to 34.61)

The RR 7.68 means that the relative risk is 7.68 higher for pregnant women with a SARS-CoV-2 infection compared to pregnant women without infection. The studies contained a total of n=1490 pregnant women (I'm not sure whether this is the number of women with infection or the total). The last bit means a 95% CI convidence interval for the estimated relative risk is somewhere between 1.70 and 34.61. Hence there is fairly high convidence that the risk is increased but by how much the risk is increased is very uncertain.

Another useful number for context is the general maternal mortality during child birth which in the US is around 20 per 100.000 birth (source). This number of deaths is estimated to be increased by a factor of around 7 due to a SARS-CoV-2 infection.

Edit: JonathanReez claims that the answer should be inconclusive so a here a few more words on what the study claims (and is correct in claiming) and what it doesn't.

First one can compute backwards that with a base rate of maternal mortality of around 20 per 100.000 and an RR of 7.68 comes out to exactly two deaths in their sample of n=1490 (equivalent to an observed maternal mortality of around 150 per 100.000 in the sample).

This turns this into a classical probability problem. The null hypothesis is that there is no effect due to corona. So how likely is it to observe 2 deaths in 1490 women if the maternal death rate is 20 per 100.000? It turns out this probability is smaller than 5% (but bigger than 1%). Hence one can conclude with 95% confidence that women with a corona infection suffer a higher maternal mortality than women without (which is what the study says). We couldn't make the same conclusion with 99% confidence.

Trying to estimate how much bigger the maternal mortality rate actually is is very difficult due to the limited data. The 2 observed deaths lead to an estimate of 7.68 higher than normal but whether the actual increase is more around twice as big or more around 30 times as big cannot be concluded from the data (the study computes this as a 95% confidence that the effect is in the interval [1.70, 34.61]).

Additionally the claim is only saying that women with a corona infection have higher maternal mortality. It does not claim that the higher mortality is due to the corona infection. This could be the case but it could also be the case that there is a confounding factor that increases both the risk of a corona infection and maternal mortality (for example race or poverty). This question cannot easily be answered with the limited amount of data and the study doesn't make any claims in this direction.

Answer 2

The CDC has data on all-cause maternal mortality from 2018, 2019 and 2020:

Year	Number of live births	Number of maternal deaths	Maternal mortality rate
2018	3,791,712	658	17.4
2019	3,747,540	754	20.1
2020	3,613,647	861	23.8

A maternal death is defined by the World Health Organization as, “the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and the site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes”

As we can see from the data, only 0.02% of pregnancies end with a maternal death, so this is a very rare event to begin with. We also see that 2020 wasn't exceptionally bad, as the increase in mortality from 2018 to 2019 (20.1/17.4 = 15%) was similar to the increase in 2020 (23.8 / 20.1 = 18%). COVID might've have had some impact on mortality during pregnancy but it's not easily visible in mortality statistics.

The other answer links to studies that attempt to quantify the relative risks of having a COVID infection but their cohorts are far too small to meaningfully study an event with a 0.02% probability. So I'd say the answer to this question is inconclusive, as we simply don't have enough data to provide a meaningful answer. Compare this to, say, all-cause mortality statistics for people above the age of 65 where there's a clear increased during the pandemic and little argument over the severity of the virus.