Today’s post is a heavy one: it’s about stillbirth. Like miscarriage or birth trauma or countless other parts of pregnancy and parenting, this is not a topic that’s easy to discuss. The result of that lack of ease is a lack of discussion. But the lack of discussion can leave people feeling unprepared and alone in loss. It also makes it more difficult to think about interventions that might change outcomes.
I hope this post will be informative but gentle, raise awareness, and provide avenues for support. But it’s also likely a tough read for many people. So take this as it works for you.
What is a stillbirth, and how common is it?
In the United States, stillbirth is defined as the birth of a baby with no sign of life after 20 weeks of gestation. Globally, the definition sometimes starts only later, at 28 weeks. I will focus on the U.S. definitions here. Before 20 weeks, fetal loss is documented as a miscarriage. Between 20 and 27 weeks of gestation it’s an “early stillbirth,” between 28 and 36 weeks a “late stillbirth,” and at or after 37 weeks a “term stillbirth.”
When a stillbirth occurs, the pregnant woman may know her baby has died in utero before delivery, or it may be discovered at the time of birth.
Stillbirth is more common than many people think. I do not say this to scare you; it is still a low risk. But like many things in pregnancy (miscarriage, birth trauma, complications), the fact that we do not discuss it means that, if it does happen, people can feel very alone.
There are about 23,000 stillbirths a year in the U.S.; that’s about 1 per 160 deliveries. This is much lower than the risk of first-trimester miscarriage (a risk of between 1 in 4 and 1 in 10, depending on when the pregnancy is detected), but it’s higher than the risk of Down syndrome (for example) and other chromosomal problems. About half of these stillbirths are early — before 27 weeks — and half are after. More on this below, but the risk increases at the end of pregnancy, especially after 41 weeks.
What happens with a stillbirth?
Sometimes a stillbirth is only discovered at the time of birth. In other cases, a fetal death in utero will be detected at an ultrasound, either a routine one or in response to a noted decline in fetal movement. However it happens, this is a devastating moment for nearly all families.
An important thing to know is that you do not have to decide immediately at that moment what to do. Assuming there isn’t a physical danger to the pregnant person, you have some time to make a decision about what to do next and when to do it.
For a stillbirth at less than 24 weeks of gestation, a dilation and evacuation (D&E) procedure is feasible and often recommended given the lower risk of morbidity to the woman. In some regions, there are providers who can perform a D&E after 24 weeks, but this depends on the fetal size and the experience of the OB-GYN. Beyond 24 weeks of gestation, delivery of the fetus will therefore typically be necessary. Because of the morbidity risks associated with a cesarean section, a vaginal birth is recommended if possible. Depending on your wishes, it should be possible to hold the baby after birth, to say goodbye. You can also take photos, and have footprints or other keepsakes made.
It’s hard to overstate how traumatic this can be. If you are going through this, please lean on the resources mentioned in this post, and any other support you have from family, providers, and friends.
What are the primary causes of stillbirth?
It should first be said that in many cases, the cause of a stillbirth is unknown. It is not always possible to do further testing or an autopsy — many families do not want this — and sometimes the cause is simply unclear. There are a few known causes, though.
- Genetic abnormalities. Approximately 15% to 20% of stillbirths have notable abnormalities or major malformations, or can be identified as having a chromosomal abnormality. Chromosomal abnormalities are a cause of a very large share of first-trimester miscarriages; in some cases, these issues are compatible with further development but not live birth. As genetic testing has become more advanced, more cases of stillbirth are being attributed to genetic causes.
- Infections. An estimated 10% to 20% of stillbirths are caused by maternal infection. Listeria, E. coli, CMV, parvovirus, and Zika are among the causes (more on COVID below).
- Placental abruption. 5% to 10% of cases are a result of placental abruption, a condition in which the placenta detaches completely or partially from the womb. This is usually, though not in all cases, a result of physical trauma (e.g. a car accident).
- Umbilical cord event. An estimated 10% of stillbirths are a result of an umbilical cord event (a knot in the cord, for example). A note here is that umbilical cord issues arise with some frequency (20% of healthy babies have a cord around the neck, for example) and do not always cause significant issues, so it is sometimes difficult to know whether a cord issue is really at fault or just a coincidence.
- Fetal growth restriction. Growth-restricted fetuses (those that are growing more slowly than expected) are at higher risk of stillbirth. This is not itself a cause, and in some cases it’s a result of one of the causes cited above (for example, genetic abnormalities). But fetal growth restriction can also be a sign of placental dysfunction, and it may be this dysfunction that is the cause in these cases.
Risk factors for stillbirth
Beyond causes, there are some identified maternal and infant risk factors for stillbirth. Stillbirth rates are higher among those who are older, who have diabetes or hypertension, who are unmarried, and who smoke or drink alcohol heavily in pregnancy. It is extremely difficult to know whether these characteristics represent biological risk factors or simply differential access to care. Rates are also higher among Black women for reasons that likely reflect medical and systemic racism. Focusing on ensuring adequate prenatal care for everyone is one crucial way to address these differentials.
Is COVID a risk factor?
There is some evidence that COVID-19 infection, especially during the Delta wave of the virus, was associated with almost a doubling of stillbirth risk. It is hard to know from the data we have how significant these impacts are, or why. One theory involves a mechanism related to placental involvement. But there is much still unknown here, including even the degree to which the risk is elevated.
The more reassuring news is that these issues were seen predominantly or exclusively in unvaccinated women, and they appear to have been significantly worse during the Delta wave of the virus relative to the current Omicron variant. These findings are a strong argument for COVID-19 vaccines before (or during, if you’re unvaccinated) pregnancy.
Are there any interventions that would decrease the risk?
A first important, baseline, intervention is good prenatal care. Issues like fetal growth restriction are more likely to be identified earlier if prenatal care is comprehensive.
There is also evidence to support a policy of inducing labor by 41 weeks. A randomized trial in Sweden, published in 2019, found that stillbirth rates were significantly increased when doctors waited until 42 weeks to induce. So induction of labor by 41 weeks is recommended (I’ve written elsewhere about the question of induction at 39 weeks versus waiting until 40 or 41; this choice is less clear).
A commonly cited intervention with the potential to lower stillbirth risk is counting kicks. There are many ways to do this, but the most codified one is the “count to 10” method: periodically (say, once a day), you see whether there are at least 10 movements you can perceive over the course of two hours. The idea is to stop when you get to 10, which takes an average of 20 minutes. Another method is to count for 30 minutes — if there are at least three movements in 30 minutes, that is reassuring.
The logic behind this approach is sensible. Decreased fetal movement (DFM) is frequently detected prior to a stillbirth, and this kind of systematic approach is easy to explain and implement. It seems logical that it might catch some cases and allow for intervention.
The empirical data on kick counting is not as compelling as one might think based on the logic. The largest trial of this approach, the AFFIRM study, included 400,000 women. The authors did not find a significant impact: the control group had a stillbirth rate of 4.4 per 1,000, versus 4.06 in the intervention group. This is about a 7% decrease, but not large enough given the sample size to show significance. Other studies have similar results. The primary downside to this intervention is possible added stress and unnecessary doctor’s visits.
Kick counting continues to be a common intervention. But these data suggest that its impacts, if they exist, are likely to be small in magnitude.
A final approach that is worth mentioning given the links between stillbirth and the placenta is the possibility of placental measurement. A lower placental volume has been linked in the data to lower birth weight and fetuses that are small for their gestational age. This suggests that placental measurement could be a marker for increased risk. I say “suggests” because, of course, it could be that some third factor is responsible for both a small fetus and a small placenta. But identifying this has the possibility — in theory — of marking people for increased follow-up.
Placental volume has generally been hard to measure in utero (the study linked above uses an MRI, which is not standard in pregnancy). However, recent research has suggested that an estimate of placental volume can be derived from straightforward ultrasound measurements.
I will caution that this approach has yet to be tested in large-scale trials, and routine measurement of placental volume isn’t recommended. It shows potential, but nothing close to certainty.
Many stillbirths cannot be prevented. More work is necessary to identify those that can.
Where can I look for support?
First and foremost, family, friends, your provider, your therapist.
Beyond this, pushpregnancy.org is an organization dedicated to ending preventable stillbirth. You can find it on social media at either @pushpregnancy or, for loss parents, at @stillcountsorg. You can also find the organization on October 15, 2022, in Washington, D.C., for a 23,000-empty-stroller march.
I very much hope this post never becomes relevant for you personally. But if it does, I hope it provides some information and support, so you do not feel quite so alone.
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