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Preeclampsia can occur after the 20th week of pregnancy.
The mother and baby can be affected by decreased blood flow to the placenta or the mother’s organs.
A Swedish midwife explains how clinicians prevent, diagnose and monitor the condition.
If you’re a woman who’s expecting or trying to conceive, you’ve probably heard of the term preeclampsia. But do you know what it means, and how it could potentially affect you if you develop this condition? Lisa Arnold, ARNP, a nurse midwife and program director for midwifery at Swedish Midwifery and Women’s Health in Ballard, WA, answers questions to explain what preeclampsia is all about.
What is preeclampsia?
It’s a combination of hypertension or high blood pressure and either protein in the urine or some degree of organ damage that may affect a woman’s liver, kidneys and brain. Preeclampsia can occur after 20 weeks of pregnancy up until potentially a few weeks postpartum; that’s the window in which it can manifest itself. We most commonly see it around term — at or after 37 weeks. It occurs in about 3 to 4 percent of pregnancies so it’s fairly common; we certainly see it with some frequency in our practice.
What causes it?
The cause is not very well understood, but there is abnormal development of the uterine blood vessels in the placenta very early in pregnancy, usually in the first trimester. This can cause decreased blood flow to the placenta as well as to some of the woman’s other organs later in the pregnancy.
So, it affects both moms and babies?
Yes. For mom, the concern is the potential organ dysfunction for the liver, the kidneys and the brain, and the risk for seizures. Later in life, there’s an increased risk for cardiovascular disease. If the mother were to develop seizures, this would be termed eclampsia. Eclampsia is extremely rare, particularly in developed countries where preeclampsia is usually caught early and treated.
For babies, because of that decreased blood flow to the placenta, we sometimes see concern for their growth and well-being. And sometimes we see a lower amount of amniotic fluid, which again is related to the decreased blood flow to the placenta.
Are there any risk factors for developing preeclampsia?
“High risk factors include women having preeclampsia in the past, especially if they developed it earlier in their pregnancy and if it was more severe; women having multiple gestations; women who have chronic hypertension and so come into pregnancy with high blood pressure; and women with preexisting diabetes, kidney disease or an autoimmune disease.
The more moderate risk factors apply to many more women — women having their first baby, who are older or who have an elevated BMI or a family history of preeclampsia; women who have IVF pregnancies with a donor egg; or women who had a small baby in a previous pregnancy. There are socio-demographic characteristics, too. African-American race or low socioeconomic status can also be moderate risk factors.
There are many factors that can contribute to preeclampsia, but one piece I think is interesting is the immunological factor. This might apply for women having their first baby or who have a donor egg, because it’s as if the body recognizes the new baby as foreign, and when the placental blood vessels develop, they don’t form the way they are supposed to, so they don’t deliver the ideal amount of blood to the placenta. For women who have had a baby and didn’t develop preeclampsia, it’s very unlikely that they will develop it in a subsequent pregnancy — that combination of genetic material has already been tested. However, if a woman has a baby with a different partner, she may be at the same risk as a new mom for getting preeclampsia because there is foreign material from the new father that the body hasn’t been exposed to before. That’s why we see a higher risk with donor eggs as well, because this is new genetic material for the mother.
Are there signs of preeclampsia women should look for?
Many women may suffer from persistent and severe headaches that are often described as the worst headache they’ve ever had. Sometimes they experience vision changes — blurred or double vision, or they’ll see flashes of light. They may have pain right underneath the ribs on the right-hand side, which is where the liver is and could indicate potential damage. If patients call us for any of those reasons in the late second or third trimester, we have them come in to do a blood pressure check to see if the symptom might be related to preeclampsia.
Is there a treatment for preeclampsia?
If women have one of the high-risk factors or three or more of the moderate-risk factors, we will recommend that they take an 81-milligram dose of baby aspirin starting around 12 weeks into their pregnancy and continuing until they deliver. The idea is that aspirin prevents some of the vessel damage that leads to the effects of preeclampsia. Many studies have shown aspirin to be effective at reducing a woman’s risk for preeclampsia. Low-dose aspirin can reduce the risk of preeclampsia by 10 to 20 percent, which is significant.
How do you look for preeclampsia in patients?
Patients that are diagnosed with preeclampsia usually have high blood pressure which, for preeclampsia, is 140/90 or higher. If a woman’s blood pressure is elevated, we order blood tests to look for organ damage, checking their liver and kidney functions. We also check urine for protein, which may indicate kidney damage. We can perform protein tests on a single void of urine, but the gold standard is something called a 24-hour urine, where the patient collects their urine over 24 hours, and we then measure the amount of protein that has been secreted during that time. With mild preeclampsia, we tend to see high blood pressure and protein in the urine but normal results from the blood draw.
Does preeclampsia affect the baby’s delivery?
For anyone who is diagnosed with preeclampsia, we recommend vaginal delivery by induction at 37 weeks. If they’re diagnosed earlier — say at 32 weeks — then we’re going to see mom quite frequently for blood pressure checks and lab tests. We’ll also perform some additional testing to make sure the baby is still doing well. We will do a non-stress test once or twice a week, during which we monitor the baby’s heart rate for 20 minutes and make sure that it looks healthy. We also do ultrasounds, usually about once a week, where we check in on baby’s well-being — we look at movement, tone, if baby is practicing breathing and amniotic fluid levels.
If any of those things are abnormal or if the preeclampsia becomes more severe — if the woman has abnormal labs or symptoms indicating organ damage — the delivery would be earlier than 37 weeks. One other thing to mention is that if patients have severe preeclampsia, they will likely be given a medication called magnesium sulfate for seizure prevention.
The only cure for preeclampsia is to deliver the placenta, and you can’t deliver the placenta until you deliver the baby. So, the goal with earlier delivery is to initiate resolution of the disease by delivering the placenta and to minimize risks to mom and baby of potential worsening preeclampsia or even eclampsia.
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If you have concerns about preeclampsia or other pregnancy complications, contact pregnancy and childbirth services at Swedish. We can accommodate both in-person and virtual visits.
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This information is not intended as a substitute for professional medical care. Always follow your health care professional's instructions.
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