Hormones
An underactive thyroid can cause irregular or absent periods, raised prolactin and an increased risk of miscarriage. It is treated with levothyroxine, with TSH rechecked regularly; requirements commonly increase in pregnancy. Never adjust thyroid medication yourself — ask the prescribing clinician.
Also known as: underactive thyroid, low thyroid
Related Canada guides
Sources
- Society of Obstetricians and Gynaecologists of Canada (SOGC) patient information
Last reviewed: September 9, 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.