Iron deficiency anemia can develop in women who have unusually heavy periods (menorrhagia), because the blood loss can deplete iron stores.

Menorrhagia is defined as losing more than 80 mL (2.7 fl oz) of blood per month. It is the most common cause of iron deficiency anemia in women. ¹

Any of the following characteristics may indicate abnormally heavy menstruation:¹

• Being unable to control blood flow with tampons alone
• Requiring more than 4 pads per day or 12 pads per period
• Passing blood clots:
  • Larger than 2 cm (0.8 in.) in diameter
  • Beyond the first day of the cycle
• Having a cycle that lasts longer than 7 days

Menstrual blood flow varies greatly from woman to woman. However, it usually remains constant from one month to the next in the same woman. Certain birth control intrauterine devices (IUDs) may increase blood flow. Use of oral contraceptives often helps lighten blood flow and may decrease the risk of iron deficiency anemia.