Rhinitis of pregnancy, or a widening of the nose in the second and third trimester, is caused by higher estrogen levels, according to WebMD. The estrogen encourages fluid retention and a thickening of mucus linings in the nasal passages and sinuses. This can sometimes produce the outward appearance of a wider nose.
Rhinitis of pregnancy can also cause a very uncomfortable cold-like congestion. This congestion can disrupt sleep and cause headaches and toothaches. This congestion unfortunately can only be treated as a symptom with normal at-home cures — like warm showers and over the counter medication. However, the congestion will likely continue throughout the pregnancy and then quickly subside in the month following delivery. Only rarely does rhinitis of pregnancy result in permanent nasal or sinus damage.