During pregnancy, estrogen and human chorionic gonadotropin (hCG) are produced. These increase the thyroid hormones in the blood. When the mother’s thyroid function is abnormal, there is a chance that the baby will get too much or not enough of the thyroid hormone. This affects the way the baby’s brain and nervous system develop.
The baby needs thyroid hormone so its nervous system and brain develop properly. Up until the 10th to 12th week of pregnancy, the baby gets all of the thyroid hormone it needs from the mother. After that time, the baby’s own thyroid begins to function, but the baby still needs the mother to get enough iodine to support proper thyroid function.
Congestive heart failure, low birth weight, developmental disabilities, premature birth, miscarriage and still birth are all possible during a pregnancy when the mother’s thyroid function is abnormal. Preeclampsia, or high blood pressure during pregnancy, and anemia, or low levels of iron in the blood that affect the way oxygen is carried to the organs, are both possible. Delivery complications, such as stalled labor or prolonged labor are also possible.
Some women may experience thyroid storms, or worsened thyroid function and symptoms, during the first trimester when the baby relies on her thyroid hormones. During the second and third trimesters, however, the woman may experience a period of remission because of the body’s natural immune system suppression that occurs during that period. The remission phase usually ends at delivery, when the thyroid storms begin again. These storms usually last two to three months and begin to stabilize as the mother’s hormones return to normal.
Approximately 8 percent of women who have delivered a baby will suffer from an inflammation of the thyroid called postpartum thyroiditis. This condition may go undiagnosed because the symptoms often mimic postpartum blues. These symptoms include lethargy, exhaustion, fatigue and moodiness.
A woman who is suffering from postpartum thyroiditis will go through a cycle of symptoms. One to eight months after delivery, the woman will go through a mild phase of hyperthyroidism lasting one to two months. From there, a period of approximately six months to a year, the woman will suffer from hypothyroidism. In most cases, after the period of hyperthyroidism, the thyroid will begin to function properly. However, in a small number of women, the thyroid is severely damaged by the inflammation and function never returns to normal. In that case, the woman will have to take synthetic hormones.
Because of the effects of thyroid dysfunction on the baby and the mother, it is necessary for a obstetrician to treat the mother, sometimes with synthetic hormones, during pregnancy and in the postpartum period.