FACT. Hair looks noticeably fuller and thicker during pregnancy because of the presence of higher levels of estrogen in the body. It does not mean new hair strands are growing rather, less hair are being shed than normal. In a normal hair growth cycle, 90% of the hair follicles are in the anagen or active phase while around 10% percent are in the telogen or resting phase. During pregnancy, increased estrogen levels prolong the growing stage of the hair follicles and prevent those in the resting stage from falling off naturally. Thus, hair appears thicker and fuller.