Yes, a pregnant or breastfeeding woman may break her fast if she feels weak and is unable to continue fasting. However, the majority of scholars state that if she is strong enough to fast without harm to herself or her child, then fasting remains obligatory. The key consideration is her health and the well-being of the baby. If fasting poses a risk, she is allowed to break her fast and make up for it later or follow the prescribed expiation based on scholarly opinions.