The endometrium is the inner lining of the uterus where an embryo implants. Its thickness changes throughout the menstrual cycle in response to estrogen and progesterone.

A thinner uterine lining may sometimes be associated with lower implantation potential, particularly during IVF or frozen embryo transfer. However, thickness is only one part of the fertility picture. Blood flow, hormone levels, uterine health, embryo quality, age, cycle timing, and medical history may also affect the chance of pregnancy.

Possible factors linked with a persistently thin lining include hormonal concerns, reduced uterine blood flow, previous uterine procedures, inflammation, or scar tissue.

If an ultrasound shows a thin lining, the result should be reviewed together with the timing of the scan and your overall fertility history. One measurement alone does not provide the full picture.