The most common cause of seizures after giving birth is eclampsia, a dangerous complication of severely high blood pressure that can develop in the days or weeks following delivery. But eclampsia isn’t the only possibility. Blood clots in the brain’s veins, sudden blood vessel spasms, dangerously low sodium levels, and worsening of pre-existing epilepsy can all trigger postpartum seizures. Understanding the different causes matters because each one looks slightly different and requires different treatment.
Eclampsia and Postpartum Preeclampsia
Preeclampsia is a condition defined by dangerously high blood pressure during or after pregnancy. When it triggers a seizure, it becomes eclampsia. Many people assume preeclampsia only happens before delivery, but it can appear for the first time in the postpartum period, sometimes in women who had perfectly normal blood pressure throughout pregnancy. The diagnostic threshold is a blood pressure reading of 140/90 or higher on two separate occasions at least four hours apart, occurring within six weeks of delivery with no other explanation. Readings at or above 160/110 are considered severe and require immediate treatment.
The biology behind these seizures involves what happens to blood flow in the brain. In preeclampsia, the pressure pushing blood through the brain’s vessels rises significantly compared to healthy postpartum women. Blood flow speeds also increase after delivery. This combination of higher pressure and faster flow puts intense strain on the walls of cerebral blood vessels, which can overwhelm the brain’s ability to regulate itself and trigger a seizure. In severe cases, the pressure can even cause bleeding in the brain.
What makes postpartum preeclampsia biologically distinct from the version that appears during pregnancy is a shift in the immune system. Women who develop it after delivery show elevated levels of certain immune cells, specifically natural killer cells, that aren’t seen in women who develop preeclampsia before birth. Researchers have also found that women who go on to develop postpartum preeclampsia have measurably different levels of placenta-related proteins in their blood even before delivery, suggesting the process may begin before the placenta is gone.
Warning Signs Before a Seizure
Postpartum eclamptic seizures rarely strike without warning. The two symptoms that matter most are a severe headache that doesn’t respond to typical pain relief and changes in vision, including blurred vision, light sensitivity, or temporary loss of vision. These symptoms reflect the mounting pressure on blood vessels in the brain and signal that a seizure may be imminent. High blood pressure itself often causes no symptoms you can feel, which is why blood pressure monitoring after delivery is critical, especially in the first week.
Blood Clots in the Brain’s Veins
Cerebral venous thrombosis (a blood clot forming in the veins that drain blood from the brain) is a less common but serious cause of postpartum seizures. Pregnancy and the postpartum period naturally shift the blood toward a more clot-prone state, and most cases of this type of clot appear after delivery rather than during pregnancy. The estimated risk is roughly 12 cases per 100,000 deliveries.
Seizures are actually more common when these clots form postpartum than during pregnancy. In one study, 60% of postpartum cases involved seizures, compared to about 35% of cases that occurred earlier. The most frequent symptom is a severe headache, present in about 73% of cases overall. Motor weakness on one side of the body, confusion, and visual problems are also common. The key difference from eclampsia is that blood pressure may not be dramatically elevated, and the headache pattern can be different. Diagnosis requires specialized brain imaging, typically a CT or MRI scan combined with venous angiography to visualize the clot.
Reversible Cerebral Vasoconstriction Syndrome
RCVS is a condition where arteries in the brain suddenly and repeatedly constrict, temporarily reducing blood flow. It can happen in the weeks after delivery and presents with what’s called a “thunderclap headache,” an explosive headache that reaches maximum intensity within seconds. Seizures, elevated blood pressure, and focal neurological symptoms like weakness or visual changes can follow.
The postpartum period itself appears to be a trigger, possibly related to the same placenta-derived proteins involved in preeclampsia. Certain medications can also provoke it, including some antidepressants (both SSRIs and other types), migraine medications, nasal decongestants, and ergot-based drugs sometimes used to manage postpartum bleeding. The “reversible” in the name is the good news: the vessel narrowing resolves on its own in most cases, though complications like stroke or brain hemorrhage can occur before it does.
RCVS can look very similar to eclampsia on initial presentation, which is why brain imaging is often necessary to tell the two apart. The hallmark thunderclap headache, particularly if it recurs in a pattern, points more toward RCVS than eclampsia.
Low Sodium From Fluid Overload
A less well-known cause of postpartum seizures is acute hyponatremia, a dangerous drop in blood sodium levels. This can happen when large volumes of intravenous fluid are given alongside oxytocin (the hormone used to stimulate contractions or control postpartum bleeding). Oxytocin has an antidiuretic effect, meaning it causes the body to retain water. When combined with large amounts of IV fluid, sodium levels in the blood can become dangerously diluted. Severe hyponatremia can cause confusion, seizures, brain swelling, coma, and in extreme cases, death. This is more of a medical management complication than a disease process, but it’s a recognized risk during and immediately after labor.
Worsening of Pre-Existing Epilepsy
For the more than 25,000 women with epilepsy who deliver babies in the United States each year, the postpartum period carries a real risk of increased seizure activity. Most get through pregnancy and the postpartum weeks without any change in seizure frequency, but roughly 37% experience worsened seizures during pregnancy or the postpartum period. The two main culprits are consistent and well documented: sleep deprivation and missed medication doses. In 68% of women whose seizures worsened, one or both of those factors were directly responsible.
Sleep deprivation alone is a powerful seizure trigger. In one study, it was the primary cause of increased seizure frequency in six out of eight pregnant women who weren’t taking seizure medications. The round-the-clock demands of a newborn make the postpartum period especially risky. For women with known epilepsy, getting help with nighttime feedings and sticking closely to medication schedules are two of the most effective things they can do to prevent breakthrough seizures.
How Doctors Tell the Causes Apart
When a seizure occurs after delivery, identifying the cause quickly is essential because the treatments differ significantly. Blood pressure readings, blood tests, and urinalysis are the starting points. But a definitive diagnosis often requires brain imaging. A CT scan can detect bleeding. An MRI with venous angiography can reveal blood clots or the vessel narrowing pattern of RCVS. In some cases, a lumbar puncture is needed to rule out infection or bleeding not visible on scans.
The overlap between conditions is what makes diagnosis tricky. Eclampsia, RCVS, and venous thrombosis can all cause headache, seizures, and high blood pressure. A reduced level of consciousness after a seizure could simply be the normal post-seizure recovery period, or it could signal bleeding in the brain. Clinicians generally cannot be confident in a single diagnosis until imaging has been completed, even when the clinical picture initially seems straightforward.
Treatment and What to Expect
For eclampsia, the primary treatment is magnesium sulfate, which is given intravenously to stop seizures and prevent recurrence. It’s typically continued for 24 hours after delivery or 24 hours after the last seizure, whichever comes later. Blood pressure is brought down with medication when readings hit 160/110 or higher. Most women recover fully, but the condition requires close monitoring because of the risk of brain hemorrhage.
Cerebral venous thrombosis is treated with blood thinners to dissolve the clot and prevent it from growing. RCVS management focuses on removing any triggering medications and controlling blood pressure while the vessel spasms resolve on their own. Low sodium levels are corrected carefully with IV fluids, though correction has to happen gradually to avoid additional brain injury. For women with epilepsy, the focus is on restoring their medication regimen and addressing sleep deprivation.
Regardless of the cause, any seizure in the postpartum period is treated as a medical emergency. The postpartum window of risk extends up to six weeks after delivery, which means new or worsening headaches, vision changes, confusion, or any seizure-like activity during that time warrants immediate evaluation.