Thin endometrium

A thin endometrium is a lining that does not thicken as expected during a treatment cycle, often described as under about 7 mm before transfer, though thresholds differ between clinics and pregnancies do occur with thinner linings. Causes include previous uterine surgery or infection, adhesions and reduced blood flow. Options include adjusting oestrogen support, extending the preparation phase, investigating the cavity or freezing embryos for a later transfer.

Also known as: thin lining, thin womb lining

Last reviewed: 8 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.