What Causes Bell’s Palsy After Childbirth?

Bell’s palsy after childbirth most likely results from the same process that causes it in the general population: reactivation of herpes simplex virus in the facial nerve, amplified by the immune and fluid-balance shifts that happen during late pregnancy and the early postpartum period. No single cause has been proven, but the leading theory points to a combination of immune suppression, increased fluid retention, and hormonal changes that together create an environment where a dormant virus can flare up and inflame the nerve that controls one side of the face. A handful of pregnancy-specific conditions, especially preeclampsia, significantly raise the odds.

Why the Postpartum Window Is Especially Risky

Bell’s palsy can strike at any point during pregnancy, but timing is not random. Research consistently finds that the third trimester is the most common period, with the weeks immediately after delivery being the second most common.¹ The postpartum period, sometimes called the puerperium, stretches roughly six weeks after birth, and it is during this stretch that new mothers are most blindsided by the sudden onset of one-sided facial weakness.

Several overlapping changes explain why this window matters. Throughout pregnancy, the immune system dials down certain responses to avoid rejecting the fetus. That immunological truce does not snap back to normal the moment delivery is over; it unwinds gradually. At the same time, extracellular fluid volume peaks near the end of pregnancy. Swelling in the narrow bony canal through which the facial nerve passes (the fallopian canal in the temporal bone) can compress the nerve and disrupt its function. In the postpartum days, fluid redistribution is dramatic as the body sheds the extra volume it carried, and that rapid shifting may worsen local swelling around the nerve before it resolves.

The Herpes Simplex Reactivation Theory

Outside of pregnancy, Bell’s palsy is widely attributed to reactivation of herpes simplex virus type 1, the same virus responsible for cold sores. The virus lies dormant in nerve ganglia and can reactivate when the immune system is weakened by stress, illness, or immunosuppression. A review of the evidence found no conclusive proof that the underlying cause of Bell’s palsy in pregnant or postpartum women differs from that in anyone else, and concluded that altered susceptibility to herpes simplex reactivation during pregnancy is the most likely explanation for the clustering of cases in late pregnancy and after delivery.²

This does not mean every postpartum case involves an active herpes infection that a person can see or feel. Reactivation often happens subclinically, meaning the virus stirs from dormancy and inflames the facial nerve without producing visible sores. The immune changes of pregnancy, particularly the shift away from certain cell-mediated defenses, give the virus a window of opportunity. Because those immune shifts are most pronounced in the third trimester and do not resolve instantly after birth, the postpartum weeks remain a period of vulnerability.

The Preeclampsia Connection

One of the strongest and most clinically important associations is between Bell’s palsy and preeclampsia, a condition marked by high blood pressure and organ stress during or after pregnancy. A large nationwide register study found that preeclampsia roughly doubled the odds of pregnancy-associated Bell’s palsy.³ When researchers looked specifically at cases arising in the postpartum period, the link was even stronger, with preeclampsia associated with about two and a half times the odds.⁴

The exact mechanism connecting the two is still debated. One leading idea is that the severely elevated blood pressure in preeclampsia causes edema or tiny blood clots (microemboli) that compress the facial nerve within its bony canal.⁵ This is consistent with the broader picture: preeclampsia involves widespread vascular dysfunction and fluid leakage into tissues, and the facial nerve’s tight passageway makes it especially sensitive to any local swelling. Some case reports have even suggested that the sudden appearance of Bell’s palsy in the postpartum period could be an early warning sign of preeclampsia developing or worsening after delivery.

A meta-analysis pooling data from multiple studies found that among pregnant patients diagnosed with Bell’s palsy, about one in ten also had preeclampsia or eclampsia, and roughly 14% had hypertension more broadly.⁶ Those numbers are high enough that clinicians encountering Bell’s palsy in a postpartum patient often check blood pressure and screen for preeclampsia, even if the woman had normal readings earlier in pregnancy.

Other Risk Factors That Emerge From Large Studies

The nationwide register study mentioned above did not stop at preeclampsia. It identified several other factors tied to a higher risk of pregnancy-associated Bell’s palsy, many of which remain relevant in the postpartum window:

High BMI: Women with a BMI in the 30–35 range had about 30% higher odds compared to normal-weight women. Obesity is linked to a pro-inflammatory state and increased fluid retention, both of which could contribute to nerve compression.
Gestational diabetes: The odds were roughly 70% higher for women with this diagnosis, perhaps reflecting metabolic and vascular changes that make the nerve more vulnerable.
Multiple pregnancy: Carrying twins or more nearly doubled the risk, likely because the physiological demands and fluid shifts are more extreme.
Herpes zoster: A diagnosis of shingles raised the odds more than sixfold, underscoring the role of viral reactivation in facial nerve inflammation.
Maternal country of origin: Women born in Africa or South America had notably higher odds, around 1.8 times, though the reasons are unclear and may involve a mix of genetic susceptibility, environmental exposures, and differences in healthcare access.

All of these associations come from a study covering the full Swedish birth population, giving them more statistical weight than case reports or small clinical series.³

Delivery-Specific Factors

When researchers isolated cases that appeared specifically in the postpartum period rather than during pregnancy, a few additional risk factors stood out. Infection during labor was associated with roughly 40% higher odds, and receiving an epidural or spinal anesthetic was associated with a modest but statistically significant increase as well.⁴

The labor-infection finding fits with the immunological picture: an active infection taxes the immune system further, potentially tipping the balance toward herpes reactivation or worsening local inflammation. The epidural/spinal link is harder to explain and deserves some caution. The association was small and could reflect confounding factors, meaning that the women who received epidurals may have had longer or more complicated labors, which themselves carry more physiological stress. Researchers have not established a plausible mechanism by which regional anesthesia in the lower spine would directly affect the facial nerve in the skull. It is worth being aware of but not something most clinicians treat as a strong causal signal.

Recovery and How It Compares to Non-Pregnancy Cases

One of the most important things a new mother with postpartum Bell’s palsy wants to know is whether her face will return to normal. The honest answer is that most women recover well, but pregnancy-associated cases do carry a somewhat worse prognosis than Bell’s palsy in the general population. A study comparing outcomes found that among women whose paralysis progressed to complete loss of movement within ten days of onset, about 52% recovered to a satisfactory level, compared with 77% to 88% of comparison patients not associated with pregnancy. For those whose palsy remained incomplete, meaning some movement was preserved from the start, recovery was satisfactory in virtually everyone.⁷

That gap matters clinically. A key reason pregnancy-associated cases may fare worse is that affected women are less likely to receive early corticosteroid therapy, which is the standard first-line treatment for Bell’s palsy in the general population.⁸ During pregnancy, both patients and clinicians are understandably cautious about medications, and steroids carry concerns about fetal exposure. But once a baby has been delivered, the calculus changes. Postpartum women can generally take oral corticosteroids with fewer concerns, and prompt treatment within the first 72 hours of symptom onset is considered the single most important factor in improving outcomes. A woman who notices sudden one-sided facial drooping or inability to close one eye in the days or weeks after giving birth should seek medical attention quickly rather than waiting to see if it resolves on its own.

Recurrence is uncommon. Research indicates that having Bell’s palsy during one pregnancy does not make it likely to happen again in a future pregnancy.⁹ That can be reassuring for women who plan to have more children and are anxious about a repeat episode.

Practical Eye Care While Recovering

One of the most immediate and overlooked concerns with Bell’s palsy is the eye on the affected side. When the muscles that close the eyelid are paralyzed, blinking and full eye closure become impossible or severely limited. This means the cornea is exposed to air, dust, and drying throughout the day and especially during sleep. Corneal damage from exposure is a genuine medical risk, not just a nuisance.

For a new mother juggling breastfeeding, sleep deprivation, and round-the-clock baby care, staying on top of eye protection can feel like one more overwhelming task, but it is not optional. Standard measures include using preservative-free artificial tears frequently during the day, applying a lubricating eye ointment at night, and taping the eyelid shut with medical tape while sleeping. Some clinicians prescribe a moisture chamber, basically a clear plastic shield that fits over the eye to reduce evaporation. If a woman notices redness, pain, light sensitivity, or blurred vision in the affected eye, that warrants urgent evaluation because it could signal corneal abrasion or ulceration.

Emotional Impact on New Mothers

The emotional toll of postpartum Bell’s palsy tends to be underestimated in clinical settings. New mothers are already navigating the physical and psychological upheaval of the postpartum period, and losing the ability to smile, close one eye, or control half of the face adds a layer of distress that goes well beyond the neurological symptoms.

A mixed-methods study exploring quality of life in women who developed Bell’s palsy during or after pregnancy found that younger women experienced greater appearance-related distress than older women. Researchers identified five core themes in women’s experiences: their encounters with the healthcare system, body image concerns, the impact on daily life, ideas for improving care, and issues specific to having Bell’s palsy during the perinatal period.¹⁰ Body image stood out: women described feeling self-conscious about photos with their newborn, struggling with breastfeeding because weak lip muscles made it harder to create a seal or caused drooling, and feeling disconnected from the joy they expected to project in early parenthood.

Healthcare experiences were also a sore point. Several women reported feeling dismissed by providers who framed Bell’s palsy as temporary and minor. While it usually does resolve, the lived experience of facial paralysis during what is supposed to be a bonding period is not minor to the person going through it. Acknowledging the emotional weight of the condition, screening for postpartum depression (which can co-occur), and connecting women with support resources are all part of adequate care.

When It Might Not Be Bell’s Palsy

Bell’s palsy is a diagnosis of exclusion. That means it is the label applied when other causes of facial nerve paralysis have been ruled out. In the postpartum setting, a few alternative diagnoses deserve consideration because they require different treatment and carry different implications.

Stroke can cause sudden facial weakness, and while it is rare in young women, pregnancy and the postpartum period do raise the risk of both ischemic and hemorrhagic stroke. A critical distinguishing feature is that stroke typically affects only the lower face on one side, sparing the forehead, because the forehead muscles receive nerve input from both brain hemispheres. In Bell’s palsy, the entire half of the face is affected, including the forehead. If a woman also has arm or leg weakness, speech difficulty, or severe headache, stroke must be urgently excluded.

Lyme disease (borreliosis) can cause facial nerve paralysis and was identified as a risk factor in the Swedish register study, where it raised the odds nearly fourfold.³ In areas where tick-borne illness is common, testing for Lyme disease is part of the workup for any new facial palsy. Other rarer causes include tumors affecting the facial nerve, middle ear infections, and autoimmune conditions, all of which a thorough clinical evaluation can help identify or rule out.

The preeclampsia connection discussed earlier also means that postpartum facial paralysis should prompt a blood pressure check. If a woman who appeared normotensive during pregnancy develops Bell’s palsy after delivery, postpartum preeclampsia remains possible and should be excluded, particularly because postpartum preeclampsia can escalate to seizures (eclampsia) if missed.¹¹

Facial Rehabilitation After the Acute Phase

Once the acute phase has passed, usually after a few weeks, some women find that recovery stalls or leaves them with residual weakness, tightness, or involuntary movement (synkinesis) on the affected side. Synkinesis happens when regenerating nerve fibers grow back along wrong paths, so that smiling causes the eye to squint, or chewing triggers a twitch at the corner of the mouth. It is more common in cases that were severe from the outset.

Specialized facial physiotherapy can help. A trained therapist works on retraining the brain-to-muscle connection through mirror exercises, gentle stretches, and neuromuscular re-education techniques. The goal is to improve symmetry and reduce unwanted movements. Electrical stimulation of facial muscles, which sounds intuitive, is actually controversial: some specialists avoid it because it may encourage abnormal nerve regrowth and worsen synkinesis. Women who are considering any form of facial rehabilitation should look for a therapist experienced with facial nerve disorders specifically, not general physiotherapy.

For women who do not recover fully after a year, options expand to include cosmetic procedures such as botulinum toxin injections to calm overactive muscles on the affected side, or surgical interventions like nerve grafts or muscle transfers in severe cases. These decisions are highly individual and depend on the degree of residual impairment, the presence of synkinesis, and the woman’s own priorities.

1
PubMed Central. Bell’s palsy in pregnancy: A scoping review of risk factors, treatment and outcomes
2
PubMed. Bell’s palsy and pregnancy
3
PubMed Central. Risk factors for pregnancy-associated Bell’s palsy: A nationwide population-based register study
4
PubMed. A nationwide population-based register study of neonatal outcomes in pregnancy-associated Bell’s palsy
5
North American Proceedings in Gynecology & Obstetrics. Postpartum Bilateral Nerve Palsy: A Harbinger for Preeclampsia?
6
PubMed. Bell’s palsy and pregnancy: Incidence, comorbidities and complications. A meta-analysis and systematic review of the literature
7
PubMed. Bell’s palsy in pregnancy: a study of recovery outcomes
8
PubMed. Bell’s palsy during pregnancy and the post-partum period: A contemporary management approach
9
Obstetrical & Gynecological Survey. Bell’s Palsy in Pregnancy
10
Elsevier / PubMed Central. Impact of pregnancy-associated Bell’s palsy on quality of life and self-perception: A mixed methods study
11
PubMed Central. Bell’s palsy with preeclampsia in pregnancy