Most common thyroid disorder occurring around or during pregnancy is thyroid hormone deficiency, or hypothyroidism. During pregnancy ligaments become softer and stretch to prepare you for labour. This can put a strain on the joints of your lower back and pelvis, which can cause backache. Extreme nausea and vomiting of pregnancy is a clinical condition termed Hyperemesis gravidarum . Hyperthyroidism refers to the signs and symptoms which are due to the production of too much thyroid hormone. Avoid iron pills if they cause constipation.Some infections that occur coincidentally during a pregnancy can cause birth defects. In women who are not pregnant, hyperthyroidism can affect menstrual periods, making them irregular, lighter, or disappear altogether. Placental abruption is the premature detachment of a normally positioned placenta from the wall of the uterus.

Some disorders are related to (are complications of) pregnancy. Morning sickness affects between 50 and 85 percent of all pregnant women during pregrncy. Thromboembolic disease is the leading cause of death in pregnant women. In thromboembolic disease, blood clots form in blood vessels. Pregnant women and their unborn children generally tolerate mild and moderate thyroid disorders without significant health problems. Fever late in pregnancy increases the risk of preterm labor. Hyperemesis gravidarum is extremely severe nausea and excessive vomiting during pregnancy. Hyperemesis gravidarum differs from ordinary morning sickness
Preeclampsia may lead to premature detachment of the placenta from the uterus (placental abruption).

Some forms of hyperthyroidism put a foetus at risk of growing slowly and being at risk for stillbirth. Rh incompatibility occurs when a pregnant woman has Rh-negative blood and the fetus has Rh-positive blood, inherited from a father who has Rh-positive blood. Symptoms include nausea, vomiting, abdominal discomfort, and jaundice. The disorder may rapidly worsen, and liver failure may develop. Each year in the UK, Hundreds of thousands of women are affected by miscarriage. Metabolism changes in pregnancy sometimes cause a need to change the dose of thyroid medications. Grief is a natural reaction to miscarriage and it is normal for it to be as intense as that after any other bereavement.