Conditions
An underactive thyroid can cause irregular cycles, anovulation and an increased chance of miscarriage, and it affects early fetal brain development. It is treated with thyroxine replacement, and requirements often rise in pregnancy, so levels are monitored more closely once you conceive.
Also known as: underactive thyroid, low thyroid
Related Australia guides
Sources
- Healthdirect Australia (healthdirect.gov.au)
Last reviewed: 10 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.