Thyroid disorders, either hyperthyroidism or hypothyroidism, can affect fertility. This is because both disorders can have a more pronounced effect on male fertility, on female menstruation and on ovulation, causing male infertility, causing female infertility or causing miscarriage during pregnancy. Patients with thyroid disorders who are planning to have children must keep their thyroid function at a very normal and stable level. Thyroid function should be stable for at least six months before considering childbirth to significantly reduce the risks associated with thyroid disorders during pregnancy.