The International Association for Study of Pain defines pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage (Raja et al., 2020). Orofacial pain (OP) is a broad term encompassing temporomandibular disorder (TMD) which includes multiple painful conditions affecting the oral, head, face, and neck areas (Shaefer et al., 2018). Orofacial pain, including painful TMD, are complex disorders rarely initiated by a single factor. These conditions are best explained by the interplay of multiple risk factors (Al-Jewair et al., 2021; Dubner, Ohrbach, et al., 2016; Slade et al., 2013). Among these, the sleep bruxism (SB)- characterized as rhythmic (phasic) or non-rhythmic (tonic) masticatory muscle activity during sleep (Lobbezoo et al., 2018)- is one of the most relevant behaviors contributing to the onset, aggravating, or persistence of TMDs (Al-Jewair et al., 2021, Crandall, 2018, Ohrbach et al., 2013). This is due to the forces that may exceed the physiologic tolerance, causing harmful effects on masticatory muscles and the TMJ (Ohrbach & Michelotti, 2018).

Previous studies in the OP field have shown a significant association between the frequency of SB and morning headaches (Manuel Blanco-Hungría, 2014), a higher number and frequency of clenching and grinding in patients with TMD and SB than patients with only TMD (Chien et al., 2020), and an association between probable SB and TMD pain complaints (Chien et al., 2020). In general, women have shown a higher prevalence in all subgroups of TMD, especially those related to muscular origin (Blanco-Hungría et al., 2016). Despite the available literature indicating SB as a possible predictor of OP, there is still insufficient scientific evidence supporting SB's role in OP symptomatology during the gravid-puerperal cycle and little is known about OP conditions, during pregnancy (Leresche et al., 2005).This cycle is a peculiar and exclusive period for women where several physiological, anatomical, and hormonal changes occur (Cai et al., 2013; Shaefer et al., 2018). In this sense, there are multiple excitatory and inhibitory mechanisms through which hormones may directly or indirectly modulate the nociceptive inputs (Fillingim & Ness, 2000). Understanding this topic in greater depth is crucial, considering that OP can impact the quality of life during the puerperal period (de Oliveira & Nadanovsky, 2006).

Therefore, this study aimed to investigate the prevalence of OP symptoms, characterized by morning jaw muscle pain or fatigue upon waking, and morning headaches, among a large sample of women who self-identified as sleep bruxers or non- sleep bruxers and who had given birth in 2019 in the municipality of Rio Grande, Southern Brazil.