Pregnancy Complications and Your Thyroidby Mary Shomon Patient Advocate
Healthy thyroid function is crucial to a healthy pregnancy and healthy baby. During the first trimester of pregnancy, a normal thyroid enlarges and increases its output of much-needed thyroid hormone for both mother and baby. Having a pre-existing thyroid condition — or developing thyroid disease during pregnancy — is a risk factor for a variety of pregnancy complications.
Overall, conservative estimates find that maternal thyroid disease occurs in up to 4 percent of all pregnancies, and the actual number may be higher.
Let’s look at some of the specific complications that can result from thyroid disease during pregnancy.
Hypothyroidism and pregnancy complications
The most common thyroid condition seen during pregnancy is hypothyroidism, a lack of sufficient thyroid hormone. Official guidelines of the American Thyroid Association and research studies have found that untreated hypothyroidism and inadequately treated hypothyroidism are associated with an increased risk of many pregnancy complications, including:
Miscarriage, also known as spontaneous pregnancy loss
Placental abruption, which is the separation of the placenta from the uterus, causing bleeding, contractions, prematurity, fetal distress, and even death to the mother and/or the unborn baby.
Gestational hypertension (high blood pressure) and preeclampsia, which occurs at twice the normal rate in women with hypothyroidism
Gestational diabetes — a temporary form of diabetes in pregnant women
Premature rupture of membranes (PROM) and preterm birth at less than 37 weeks of gestation
The need for an induced labor
Breech presentation, which usually requires surgical cesarean section (C-section) delivery
Need for C-section delivery
Heart rhythm irregularities in the fetus, including elevated heart rate (tachycardia) and low heart rate (bradycardia)
Lower APGAR score— an assessment of the newborn’s appearance, pulse, grimace, activity, and respiration
Compared with women who had no thyroid disease, pregnant women with hypothyroidism are also twice as likely to be admitted to the intensive care unit (ICU) during and after labor and delivery.
Hyperthyroidism and pregnancy complications
Hyperthyroidism — an overactive thyroid — during pregnancy is associated with increased risk of:
Severe morning sickness (hyperemesis)
Hypertension in pregnancy
Maternal heart failure
The need for an induced labor
Fetal growth restriction and low fetal birth weight
Fetal tachycardia (high heart rate)
Compared with women who had no thyroid disease, pregnant women with hyperthyroidism are also four times as likely to be admitted to the ICU during and after labor and delivery.
Thyroid surgery during pregnancy
In most cases, thyroid surgery is postponed until after your baby is born. But in some cases, if a cancerous tumor is growing rapidly, or a tumor or goiter is impairing your breathing or swallowing, thyroid surgery is performed during pregnancy.
Thyroid surgery during the first trimester increases the risk of risk of miscarriage, and thyroid surgery during the third trimester increases the risk of preterm labor. As a result, surgery is only performed during the second trimester, when it is considered safest for both mother and baby.
Researchers have found, however, that there is a significantly higher rate of post-surgical complications in pregnant women having a thyroidectomy, compared to non-pregnant women. Specifically, there were increased risks for:
Hypokalemia (low calcium levels)
Laryngeal nerve damage
Longer hospitalization and recuperation time
It’s important to note, however, that those surgeons who did a high volume of thyroid surgeries had significantly lower complication rates. According to researchers: “It appears to be essential that pregnant patients who require thyroidectomy be directed to high-volume surgeons to optimize their outcomes.”
What should you do?
Some research studies suggest that more careful and thorough thyroid treatment during pregnancy can reduce your risk of complications and adverse outcomes.
Don’t assume, however, that you are receiving sufficient treatment. Research shows that up to 60 percent of hypothyroid women treated with levothyroxine have elevated TSH levels during pregnancy. This is evidence that when you are pregnant, you are at significant risk of going through periods of inadequate treatment.
If you are pregnant and have thyroid disease, it makes sense for you to work with your healthcare provider to ensure that you are receiving the best possible treatment for your thyroid condition.
At a minimum:
Familiarize yourself with the official 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. These guidelines contain the most current recommendations regarding optimal thyroid treatment during your pregnancy.
Insist on frequent thyroid testing during and after your pregnancy. Typically, patients are tested each trimester then 6 weeks postpartum.
Ensure that all the healthcare providers on your team are aware of your thyroid condition.