Is it harder to get pregnant if you have hyperthyroid?

Yes: Abnormal thyroid function, whether hyper- or hypo-thyroidism is very often associated with reproductive problems in women. Unlike hypothyroidism (under-active thyroid, ) which is often asymptomatic and usually fairly low-risk, hyperthyroidism can be extremely dangerous if not controlled. Generally when thyroid levels are normalized with treatment, reproductive outcomes can be excellent.