What causes a thin uterine lining?

Thin lining: At certain times of your cycle the lining is thin - immediately after your period. Estrogen thickens/ grows the uterine lining. A low amount of estrogen production will result in a thin lining. The most common thing that causes a thin lining in young women is hormonal contraceptives (pills, depo, mirena, (levonorgestrel) NuvaRing ). Here, it is normal and not an indication of any problem.