A pregnant woman developed facial paralysis weeks before she was due. After giving birth, she still can't smile.

• A pregnant woman noticed half of her face was paralyzed shortly before her due date.
• Three months later, she still can't close her eye, wrinkle her nose, or move her lip.

A new mom has been unable to move half of her mouth for nearly three months due to a bout of facial paralysis that started during her final trimester of pregnancy.

Elena Sheppard, 35, was weeks away from her due date when one day, her husband noticed that one side of her face was drooping as she drank her coffee.

She told Good Morning America that she woke up that morning with a "weird" feeling around her mouth, and soon, she was unable to close one eye or scrunch her nose.

Sheppard was diagnosed with Bell's palsy, a condition that's characterized by weakness or paralysis on one side of the face. Bell's palsy comes on suddenly and without a clear cause, and it usually goes away within a few weeks, according to the National Institutes of Health.

However, Sheppard's symptoms have continued for about three months after her diagnosis. In that time, she gave birth to healthy twin boys, but she still hasn't been able to move her mouth into a full smile.

"It's more scary than frustrating honestly," she told GMA. "You can't help but think, 'Is this what my face is gonna look like forever?'"

Why pregnancy can increase the risk of facial paralysis

While the underlying cause of the condition is not yet understood, pregnancy is a known risk factor for Bell's palsy. According to the Facial Paralysis Institute, pregnant women are three times more likely to experience Bell's palsy compared to non-pregnant women, and it's most commonly seen in the third trimester.

High blood pressure and obesity may further increase the risk of facial paralysis during pregnancy, along with a few other comorbid conditions. Bell's palsy has been associated with diabetes, Lyme disease, multiple sclerosis, and infections during pregnancy, according to Johns Hopkins Medicine.

Doctors have theorized that the Herpes simplex virus, which usually causes cold sores, could be involved in cases of facial paralysis. Changes in immune function during pregnancy may allow the virus to become active, leading to inflammation and swelling around the facial nerve.

The theory needs to be backed up with more research, but it's likely viruses play a role. Other viruses thought to be linked to Bell's palsy include chicken pox, shingles virus, Epstein-Barr virus, and West Nile virus, among others.

There's no cure, but steroids and physical therapy can help

Overall, Bell's palsy affects less than 1% of the US population, according to the NIH. Facial paralysis is not considered a common side effect of pregnancy, and when it does happen, it usually resolves itself within three weeks.

Bell's palsy may be treated with steroids to reduce inflammation, physical therapy to stimulate the facial nerve, and antiviral medication to address any underlying cause of illness, according to Johns Hopkins. Painkillers may also be appropriate for treating associated headaches, but there's no real cure for the mysterious facial paralysis.

Sheppard's symptoms have only improved slightly since she was diagnosed. At the start of her illness, she had to tape her eye shut because it wouldn't close on its own. Now, she told GMA that her affected eye still tears up from constant exposure to the environment.

Long-term complications from Bell's palsy can include damage to the cornea or dryness in the affected eye, which can be helped with eye drops.

The one-sided facial droop associated with Bell's palsy can also look like the early stages of a stroke, so it's important to seek medical attention if you experience facial paralysis — during pregnancy or otherwise.