COVID & Pregnancy

Prevalence, severity, birth, breastfeeding—this piece covers it all

When a new disease emerges, or there is an outbreak of any type of disease, it is natural to worry more about vulnerable groups. This includes (typically) children, the elderly, those who are immunocompromised and pregnant women. Pregnant women are considered higher risk than others in part because pregnancy wears you down physically, and in part because some diseases can impact the pregnancy itself or the fetus.

It is not surprising, then, that pregnant women have been of particular concern with respect to COVID-19. This is especially true because two closely related viruses — the original SARS and MERS — are often more serious in pregnant women.

But the good news is that most of what we now know about pregnant women and COVID-19 is reassuring. Pregnant women do not seem to be more likely than other women of their age group to have COVID-19 and those who do contract the virus do not seem to experience more severe illnesses.

But that’s just the bottom line. In this explainer, we look into the details of the disease in pregnant women and their babies, with the highlights summarized in the infographic below:

Prevalence and Severity

First: evidence about the rates of infection among pregnant women.

An obstetrics practice in New York monitored all of their patients for symptoms of COVID-19 and found that of 757 patients, 12% had known or suspected COVID-19. Nearly all of these cases were mild or moderate. In Seattle, on the other hand, only 2.7% of screened patients tested positive for the virus. This lines up with general prevalence levels across different places: Seattle had fewer cases than New York. A review of several studies echoes these findings that pregnant women do not seem to be more likely to get infected than non-pregnant women.

Generally, the evidence indicates that pregnant women do not seem to experience more severe versions of COVID-19. A review of several studies notes that the clinical characteristics of pregnant women are similar to those of non-pregnant women, meaning they experience similar symptoms and severity.

However, a new CDC analysis of pregnant women finds that they are more likely to be hospitalized than non-pregnant women. The analysis compares 8,207 pregnant women aged 15-44 to 83,205 non-pregnant women in the same age group. All women had confirmed COVID-19 infections. 31 percent of pregnant women were hospitalized as compared to 6 percent of non-pregnant women. A significant limitation of the study is that it does not adjust for hospitalizations for labor and delivery, or for other non-COVID hospitalizations. We would expect even in periods without COVID-19 that pregnant women would go to the hospital more.

The study also looks at admission to the ICU and ventilator usage. They find higher rates for pregnant women but these differences are much smaller (1.5 percent vs. 0.9 percent for the ICU and 0.5 percent vs. 0.3 percent for mechanical ventilation). These numbers are also generally extremely small, highlighting that this is a fairly low risk group. Another caveat to keep in mind: doctors are often more cautious in treating pregnant people so hospitalization alone may not reflect the true severity of the disease. Generally, any illness in pregnancy is taken more seriously, for good reason. The data collection approach in this study makes it difficult to draw strong conclusions about whether COVID-19 is actually more serious in pregnant women.

Prenatal care

Since pregnant women aren’t at an elevated risk, it’s natural to ask if you can continue to go to your prenatal appointments if you’re pregnant. While this is ultimately at the discretion of your doctor, you should not skip prenatal appointments. Not having prenatal check ups at all can entail a significant risk. For example, a missed case of preeclampsia can be extremely dangerous for you and your baby.

Depending on the prevalence of the virus in your state, your doctor may want to conduct some appointments via telemedicine if you have a low-risk pregnancy. If you are able to go in person to your prenatal appointments, there are several precautions you can take to protect yourself from contracting COVID-19. Wear a mask, wash your hands, and try to maintain a distance of at least six feet from the other patients in the office.

Birth

Hospitals have adapted quickly as the virus spread, and this includes their labor and delivery units. So, your birth experience will likely depend on how severe the pandemic is in your area. Many hospitals, including those in New York, only allow one support person during labor and require that person to be gloved and masked. All other visitors are restricted. The support person may also be screened for symptoms of the virus before they are allowed to enter the hospital. Several hospitals have begun testing laboring women for COVID-19, even if they are asymptomatic. If you test positive, hospital staff will take extra precautions to ensure you don’t spread the virus. You can check the website of the hospital where you plan to deliver to see their full policy about delivering during the pandemic.

Given the level of uncertainty we’re currently facing, if you’re pregnant you might wonder about inducing labor at 39 weeks. This does give you additional control over the timing of labor. A recent large randomized trial (our gold standard for evidence) found that women who induced labor at 39 weeks had lower rates of C-sections and that their babies did equally as well as those who were not induced. This is reassuring if you want to induce labor at 39 weeks. If you have scheduled an induction or C-section, the hospital may ask you to get tested for COVID-19 in advance so they can have the results to prepare appropriately for your arrival.

Finally, a note about home birth. It might be tempting to think you should just skip the hospital altogether to avoid exposure to the virus and the restrictive visitor policies. However, you should not switch to a home birth plan if this hasn’t been your plan all along, especially if you are late in your pregnancy. Home births are much safer with experienced providers and it may be difficult to find one. Further, a relatively large share of home births, especially a first birth, end up requiring emergency hospital transport anyways. This is more likely to expose you to the virus than an orderly admission through the delivery ward.

Mother to Infant Transmission

Mother to infant transmission of COVID-19 is relatively rare. A recent review summarizes 179 cases of women with COVID-19 around delivery. Of these, only eight infants showed evidence of infection and most of these cases were asymptomatic or mild. Another review finds no evidence of transmission among 31 infected mothers. No infection was detected in the babies or in the placentas of infected mothers. While we still need more evidence about whether the virus can be transmitted in-utero, this seems to be very rare as well. Most of the infections detected in newborns likely occurred during or after birth.

While infection in the womb is rare, a recently published case study found that transmission through the placenta is possible when a 23-year old mother tested positive for the coronavirus at 35 weeks and delivered an infant positive for COVID-19 three days later. Although the pregnancy had been otherwise healthy, heart monitoring indicated signs of a distressed fetus and the baby was delivered by emergency cesarean section. The newborn had mild respiratory symptoms and a brain scan suggested that there was injury to white matter, which could’ve been caused by inflammation in the brain. The placenta as well as the blood of both the mother and the baby was tested, and results indicated that the virus had reached the placenta, replicated, and then transmitted to the fetus. Many scientists have deemed this evidence convincing that placental transmission is possible, but note that the data overall suggests this is extremely rare.

Most infections in healthy, non-preterm babies are mild or asymptomatic. A review of several studies emphasizes that the outcomes of babies born to infected mothers are not worse than those of babies born to mothers who are not sick. In the case study described above, the baby gradually recovered and left the hospital after 18 days — but note that this was also a preterm birth. While there are a few reports of infants dying after becoming infected with COVID-19, these babies were also very preterm and infant death is overall rare.

Even though most cases in newborns are asymptomatic or mild, you should still take precautions to prevent your baby from contracting the virus if you are sick. In the hospital, this might mean mandated separation, similar to what is done if you have the flu. Once you get home, it might mean wearing a mask and washing your hands thoroughly.

Breastfeeding

The virus has not been detected in breast milk so it is safe to feed your baby breast milk even if you are sick. The main concern in this case is passing the virus through respiratory droplets while breastfeeding (see our Path of the Virus Explainer for more about how the virus spreads). If you are sick but still want to breastfeed, you can consider pumping until you are no longer contagious. A recent review of 114 infected mothers emphasized there is no evidence of infection from breast milk. A few studies covered in this review found antibodies in breast milk, suggesting that it may offer some protection against infection, but more evidence is needed to say anything conclusive.

Scary Studies

Finally, let’s touch on some of the scarier studies that have come out about COVID-19 and pregnancy. There has been one report of a miscarriage in a COVID-19 patient in which the authors suggest the virus may have been responsible for the miscarriage after finding the placenta carried SARS-CoV-2. However, this is only a single case and while the mother was infected, it’s very difficult to say for sure COVID-19 was the cause of the miscarriage. Some people have COVID-19 and some people miscarry in their second trimester — we need more research with larger samples to be able to say anything conclusive about a causal relationship. And it’s worth noting that a different study did not find evidence of infection in the placentas of women who tested positive for COVID-19. Another study of 16 infected mothers finds a higher rate of vascular abnormalities in the placentas, but this isn’t linked to any issues for the mothers or their babies — all of the deliveries in the third trimester were normal.

Another concern is the risk associated with fever during pregnancy. Too high of a body temperature has been linked to neural tube defects, and fever is one of the common symptoms of COVID-19. Perhaps the best study we have about this association follows 10,000 women in Denmark, 8,000 of whom had a fever during early pregnancy. This study does not find any evidence to support the link between maternal fever and birth defects. While we still need more research to understand if COVID-19 has any effects during early pregnancy, it’s unlikely that fever alone will cause significant birth defects.

The Bottom Line

Pregnancy itself does not seem to be a significant risk factor for COVID-19. Pregnant women tend to be infected at a similar rate as non-pregnant women of the same age, and they do not experience more severe illnesses. Further, transmission from mothers to infants is relatively rare. It’s possible to transmit the virus in-utero, but it is extremely rare and we’re still learning more about in-utero transmission. Even in cases where infants do contract the virus, these are usually asymptomatic or mild cases. While you should still take precautions to prevent infection if you are pregnant, you can be reassured that if you do get COVID-19, you and your baby will likely be just fine.

This issue was adapted from a post on the site available here. Please feel free to share your thoughts, questions, and concerns — you can get a hold of us via email, TwitterInstagram, and the site itself.