Pregnancy and fasting

Lens adapted to this topic: What clinical guidance and research support

Clinical guidance generally takes a precautionary, individualized approach. It favors regular nutrition and hydration during pregnancy, particularly when diabetes, low iron or other complications are present, and recommends medical advice before fasting. Reviews of Ramadan fasting report mixed outcomes and emphasize limitations in the evidence, so they do not establish universal safety or harm.

• Not fasting makes it easier to maintain hydration, a healthy diet and stable blood sugar; this is especially relevant in pregnancies complicated by gestational diabetes.
• Australian public-health guidance says long-term effects are insufficiently understood and recommends discussing when and how to fast with a doctor and religious leader.
• A 2025 umbrella review and earlier systematic review assess Ramadan fasting evidence on pregnancy and birth outcomes, reflecting an active evidence base rather than a settled conclusion.
• Clinical patient guidance advises pregnant people with diabetes, low iron or other health concerns not to fast, and to stop and seek advice if they feel unwell.

Lens adapted to this topic: What conditional-fasting advocates and dissenting evidence support

A conditional perspective distinguishes prolonged or weight-loss-oriented intermittent fasting from religious fasting that is planned around eating and drinking windows. It argues that some healthy pregnant people may choose to fast with monitoring and appropriate nutrition, while acknowledging that evidence is incomplete and that exemptions exist when fasting may cause harm.

• Some research has found no clear effect of fasting during pregnancy on birth weight or preterm birth, though other studies report possible adverse effects and the overall evidence remains mixed.
• Religious-fasting guidance notes that many traditions include rules or exemptions intended to protect pregnant and breastfeeding people, supporting individualized decisions rather than a universal rule.
• Ramadan fasting can differ from calorie-restricted intermittent fasting because the timing, duration, dietary composition and hydration practices are distinct; evidence about one pattern should not automatically be generalized to all fasting.
• A 2024 systematic review specifically identified uncertainty about long-term offspring health after time-restricted eating during pregnancy, indicating that short-term birth outcomes alone may not resolve the question.