Bell's palsy in pregnancy and puerperium

Pregnancy-associated Bell's palsy (Bell's palsy in pregnancy and puerperium, i.e., the first 6 weeks after childbirth) is thought to be more common than in the general population. Still, incidence numbers differ as earlier study populations have been small. The reason for this supposed higher incidence remains unclear. The most commonly discussed hypotheses are that either edema, due to excessive body fluid caused by pregnancy, or herpes simplex reactivation, due to pregnancy-associated immunosuppression, cause damage of the facial nerve. Additionally, some studies have reported a poorer prognosis among women with Bell's palsy associated with pregnancy, whereas another study indicated a more favorable prognosis. Co-morbidities, such as gestational hypertension, preeclampsia, high BMI, and low Apgar score, are more common among women with pregnancy-associated Bell's palsy in some studies. In contrast, others could not show this association. No prior studies have investigated the degree of depression, facial disability, or quality of life in women with pregnancy- associated Bell's palsy.

Study I is a retrospective study in which women who developed Bell's palsy during pregnancy or puerperium between 2005 and 2015 in Stockholm were recruited. Women with Bell's palsy without connection to pregnancy served as controls. Women with Bell's palsy in pregnancy had poorer facial outcomes than women with Bell's palsy in puerperium or without connection to pregnancy.

Study Il is a prospective study where 31 women with Bell's palsy in pregnancy and puerperium were included as they were referred in the acute phase to the Ear, Nose, and Throat Department at the Karolinska University Hospital in Stockholm between the years 2005 to 2015. As comparison served 31 pregnant and puerperal women without Bell's palsy during the same time period. Patient- reported depression scores did not differ significantly between groups. The patient's experience of facial function and quality of life did not correlate to the physician's grading of facial functioning.

Studies III and IV are based on data from the National Board of Social Health and Welfare in Sweden. Study III investigated maternal risk factors associated with Bell's palsy during pregnancy and puerperium. High BMI, geographical origin from Asia, Africa, and South America, multiple pregnancy, preeclampsia, and gestational diabetes were associated with pregnancy-associated Bell's palsy.

Study IV investigated neonatal risk factors, showing that women with Bell's palsy in pregnancy did not have a higher risk of adverse neonatal outcomes. In comparison, women with adverse neonatal outcomes had a higher risk for Bell's palsy in the puerperium. The incidence of pregnancy-associated Bell's palsy in Sweden between 2005 and 2015 was calculated to be 171.6 per 100,000 pregnancies, compared with the general population, where earlier studies have reported an incidence of 23-53 per 100,000 per year.

In conclusion, Bell's palsy is more common in pregnant and puerperal women than in the general population. A higher degree of depression could not be shown among these women, but larger study groups are needed to draw further conclusions about the psychological burden of the disease. Several maternal risk factors were associated with pregnancy-associated Bell's palsy. Bell's palsy during pregnancy did not increase the risk of adverse neonatal outcomes, but adverse neonatal outcome increased the risk of developing Bell's palsy after delivery, during puerperium.

List of scientific papers

I. Lansing, L., Wendel, S.B., Hultcrantz, M. and Marsk, E. (2023). Bell's Palsy in Pregnancy and Postpartum: A Retrospective Case-Control Study of 182 Patients. Otolaryngol Head Neck Surg. 168: 1025-1033. https://doi.org/10.1002/ohn.188

II. Lansing L, Brismar Wendel S, Wejde Westlund E, Marsk E. A longitudinal study of facial function, quality of life, and depression in Bell's palsy during pregnancy and puerperium. Sci Rep. 2024 Oct 22;14(1):24890. https://doi.org/10.1038/s41598-024-75552-5

III. Lansing L, Marsk E, Brismar Wendel S. Risk factors for pregnancy- associated Bell's palsy: a nationwide population-based register study. [Submitted]

IV. Lansing L, Marsk E, Brismar Wendel S. A nationwide population- based register study of neonatal outcomes in pregnancy associated Bell's palsy. [Submitted]