The contraction and expansion of the uterus following childbirth are known to cause postpartum cramps (Dashe, Bloom et al. 2018), with more than 80% of women experiencing after-pains following vaginal delivery (Evcili and Didem 2019). After-pain is also prevalent among multiparous women (77%) (Jangsten, Bergh et al. 2011) due to increased central nerve sensitivity, decreased uterine muscle strength following multiple deliveries, or an enlarged uterus (Betts 2005). After-pain can be significant within the first 12-24 hours during the first four days (Evcili and Didem 2019). In general, 95% of women experience after-pain on the first day after delivery, while 65% of them tolerate pain until the tenth day (Holdcroft 1999). Postpartum pain and discomfort have negative effects on women’s self-care, functional ability, breastfeeding and infant care, as well as the emotional bond between mother and baby (Rezaeean et al., 2017, Perry et al., 2019). Mothers may also experience anxiety, sleep and emotion disorders, and depression (Yerby, 2000, Madineh and Ghaheri, 2005, Shohani et al., 2013). (Evcili and Didem 2019) reported that the severity of postpartum after-pain influenced breastfeeding self-efficacy.

The uterus contracts through the activation of oxytocin produced in the hypothalamus or prostaglandins generated by cyclooxygenase (Marifah and Suryantini 2017). The main cause of after-pain is the production and release of prostaglandins (Grant, Agoliati et al. 2019). Uterine contractions release chemical mediators of pain, such as bradykinin, leukotriene, prostaglandin, serotonin, and lactic acid (Kheiriyat, Tadayon Najafabadi et al. 2016).

Nonsteroidal anti-inflammatory drugs (NSAIDs) (Ogunfowokan and Babatunde 2010) such as Mefenamic acid inhibit the cyclooxygenase enzyme and reduce the action of inflammatory mediators such as prostaglandins (Yeh, Chen et al. 2005), making them effective for pain relief (Deussen, Ashwood et al. 2020). However, these treatments may lead to side effects such as headache, dizziness, heartburn, constipation, drowsiness, and gastrointestinal bleeding. Increased postpartum hemorrhage is the most serious adverse effect associated with NSAIDs (Huang, Tsai et al. 2002). A portion of the drug (approximately 1% of the total) enters breast milk and may have negative effects on newborns (Vahidi and Eranmanesh 2011). Therefore, the use of medicinal plants for pain relief has received considerable attention in recent years (Rezaeean, Abedian et al. 2017).

Sesame, scientifically known as sesamum indicum, is a plant in the Pedaliaceae family that is laxative, diuretic, milk-enhancing, and anti-anemic (Hadad, Habibi et al. 2006). Palmitic acid, oleic acid, linoleic acid, and lecithin are all available in sesame oil. Lecithin is an acetylcholine precursor that reduces pain by synthetizing acetylcholine and activating nicotinic receptors. The fatty acids in diets containing sesame oil inhibit prostaglandin E synthase, which mediates the conversion of cyclooxygenase-1 and cyclooxygenase-2 to prostaglandin E2, thereby increasing the pain perception threshold (Ji, Li et al. 2010). Sesame oil is also rich in polyunsaturated and monounsaturated fatty acids, as well as vitamin E, which regulate inflammatory and immunological mediators (Haidari, Mohammad Shahi et al. 2012). Sesame oil contains 39.7 g of monounsaturated fatty acids and 41.7 g of polyunsaturated fatty acids per 100 g (Vermeer 2012). A study conducted by Askari, Alavi et al. 2016 evaluated the impact of back massage with sesame oil on childbirth pain and time in nulliparous women. It was found that sesame oil reduced pain during the first, second, and third stages of labour. Additionally, Haidari, Mohammad Shahi et al. (2012) suggested that sesamin and alpha tocopherol in sesame reduce the severity of dysmenorrhea pain by modifying the biosynthesis of eicosanoids.

Abdalla (2014) reported that the daily consumption of 100 g of sesame increased hemoglobin levels in pregnant women during their second and third trimesters but had no negative side effects, such as increased bleeding during pregnancy or after childbirth. In one study, it was reported that sesame seeds were effective in reducing dysmenorrhea (Mohammadian, Ghoreishi et al. 2017). Existing data support the hypothesis that sesame seeds may possess antioxidant and anti-inflammatory properties (Hirata, Fujita et al. 1996).

Johnson, Bergfeld et al. (2011) reported no specific contraindications for the use of sesame or its products, except for individuals with a history of sesame allergy. Healthcare providers are mandated to address and alleviate patients’ pain, enhance their physical comfort, improve their quality of life, and minimize their length of hospital stay (Perry, Potter et al. 2019). After-pains can have a negative impact on the health of mothers, infants, and families (Dastjerdi, Darooneh et al. 2019), and as no study has investigated the effect of sesame oil on after-pains, the present study aimed to investigate the impact of sesame soft gels on after-pains in multiparous women.