Hypothyroidism can significantly impact fertility and pregnancy outcomes. In women, it can cause menstrual irregularities and ovulation problems, reducing fertility. During pregnancy, untreated hypothyroidism increases the risk of miscarriage, preterm birth, and developmental issues in the baby. It's crucial for women with hypothyroidism to manage their condition closely before and during pregnancy, with regular monitoring and adjustments to thyroid hormone replacement therapy, to ensure a healthy pregnancy and minimize risks to both mother and child.