Characteristics of women who fast during pregnancy: findings from the Kuwait Birth Cohort study

Fasting during pregnancy is a widespread practice in Muslim communities, yet its health implications remain poorly understood. A lack of conceptual frameworks and limited understanding of the characteristics of women who fast during pregnancy have hindered research in this area. This study examines the differences in several nutritional biomarkers between women who fasted and those who did not and identifies factors associated with fasting behaviour. We analysed data from the Kuwait Birth Cohort in which information on fasting, sociodemographic characteristics and health behaviours was collected via structured interviews between 2017 and 2021. Clinical and laboratory data were extracted from medical records. Predictors of fasting were identified using Least Absolute Shrinkage and Selection Operator (LASSO) logistic regression with 5-fold cross-validation, followed by Poisson regression with robust standard errors. Among 1087 women with available data, 581 (53·4 %; 95 % CI 50·4 %, 56·4 %) reported fasting during pregnancy (19·5 % in the first trimester, 25·1 % in the second and 10·1 % in the third). Women who fasted had significantly lower levels of ferritin (P = 0·048), vitamin B₁₂ (P = 0·001), erythrocytes folate (P < 0·001), 25-hydroxyvitamin D (P = 0·002) and vitamin D binding protein (P = 0·011), but higher parathyroid hormone (P = 0·011). Predictive models based on sociodemographic and clinical factors showed limited predictive ability. This study indicates that fasting during pregnancy is a common practice among women in Kuwait and is associated with lower levels of key nutrients such as vitamin D, RBC folate and vitamin B₁₂. Fasting during pregnancy appears to be driven more by personal, religious and cultural influences than by identifiable clinical or sociodemographic characteristics.