Massive hair loss between 4 and 6 months postpartum is a very common hormonal occurrence caused by the sudden drop in estrogen levels. While it feels alarming, it is almost always temporary and resolves on its own by the baby's first birthday as your hormones regulate. Focus on maintaining a high-protein diet, taking prescribed postnatal vitamins, and handling your hair gently with soft products; if you are worried about deficiencies, have your doctor check your Vitamin D, B12, and iron levels.