Often, the process of pregnancy and childbirth can trigger physical changes in your body, which then affect your hair adversely. This is a more common post childbirth rather than during pregnancy. The primary reason is the fact that estrogen levels, which have risen during pregnancy and are responsible for your thick hair throughout those nine months, suddenly drop once you give birth. This, combined with vitamin deficiency, can lead to post-partum hair fall. Deal with this by visiting your gynaecologist or trichologist, who will most likely give you a vitamin-rich diet chart and vitamin supplements to combat this, as well as suggest certain lifestyle changes and shifts in what products you use.