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Thyroid disease linked to preeclampsia, preterm birth

Recent data suggest that thyroid diseases are associated with an increased risk for several adverse outcomes among pregnant women, including preeclampsia and preterm birth. These women also were more likely to be admitted to the ICU, according to NIH researchers.

“In the United States, at least 80,000 pregnant women each year have thyroid diseases,” Tuija Männistö, MD, PhD, of the NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), said in a press release. “These women are at increased risk of having serious adverse pregnancy outcomes, including hypertension and preterm birth. They also have a higher rate of labor inductions and other birth interventions.”

Männistö and colleagues aimed to examine the complications of pregnancy linked to common or uncommon thyroid disease by analyzing single pregnancies (n=223,512) from the retrospective cohort, Consortium on Safe Labor (2002-2008).

According to data, primary hypothyroidism was associated with an increased risk for preeclampsia (OR=1.47; 99% CI, 1.20-1.81), superimposed preeclampsia (OR=2.25; 99% CI, 1.53-3.29), gestational diabetes (OR=1.57; 99% CI, 1.33-1.86), preterm birth (OR=1.34; 99% CI, 1.17-1.53), induction (OR=1.15; 99% CI, 1.04-1.28), cesarean section (pre-labor OR=1.31; 99% CI, 1.11-1.54; after spontaneous labor OR=1.38; 99% CI, 1.14-1.66) and ICU admission (OR=2.08; 99% CI, 1.04-4.15).

The researchers wrote that iatrogenic hypothyroidism was associated with an increased likelihood of placental abruption (OR=2.89; 99% CI, 1.14-7.36), breech presentation (OR=2.09; 99% CI, 1.07-4.07) and cesarean section after spontaneous labor (OR=2.05; 99% CI, 1.01-4.16).

Furthermore, the researchers wrote that hyperthyroidism was linked to an increased risk for preeclampsia (OR=1.78; 99% CI, 1.08-2.94), superimposed preeclampsia (OR=3.64; 99% CI, 1.82-7.29), preterm birth (OR=1.81; 99% CI, 1.32-2.49), induction (OR=1.40; 99% CI, 1.06-1.86) and ICU admission (OR=3.70; 99% CI, 1.16-11.80).

These findings highlight a need for further research to determine whether women with appropriate treatment have a greater risk for developing pregnancy complications caused by the disease or whether treatment can stop adverse outcomes.

Disclosure: The researchers report no relevant financial disclosures.

Recent data suggest that thyroid diseases are associated with an increased risk for several adverse outcomes among pregnant women, including preeclampsia and preterm birth. These women also were more likely to be admitted to the ICU, according to NIH researchers.

“In the United States, at least 80,000 pregnant women each year have thyroid diseases,” Tuija Männistö, MD, PhD, of the NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), said in a press release. “These women are at increased risk of having serious adverse pregnancy outcomes, including hypertension and preterm birth. They also have a higher rate of labor inductions and other birth interventions.”

Männistö and colleagues aimed to examine the complications of pregnancy linked to common or uncommon thyroid disease by analyzing single pregnancies (n=223,512) from the retrospective cohort, Consortium on Safe Labor (2002-2008).

According to data, primary hypothyroidism was associated with an increased risk for preeclampsia (OR=1.47; 99% CI, 1.20-1.81), superimposed preeclampsia (OR=2.25; 99% CI, 1.53-3.29), gestational diabetes (OR=1.57; 99% CI, 1.33-1.86), preterm birth (OR=1.34; 99% CI, 1.17-1.53), induction (OR=1.15; 99% CI, 1.04-1.28), cesarean section (pre-labor OR=1.31; 99% CI, 1.11-1.54; after spontaneous labor OR=1.38; 99% CI, 1.14-1.66) and ICU admission (OR=2.08; 99% CI, 1.04-4.15).

The researchers wrote that iatrogenic hypothyroidism was associated with an increased likelihood of placental abruption (OR=2.89; 99% CI, 1.14-7.36), breech presentation (OR=2.09; 99% CI, 1.07-4.07) and cesarean section after spontaneous labor (OR=2.05; 99% CI, 1.01-4.16).

Furthermore, the researchers wrote that hyperthyroidism was linked to an increased risk for preeclampsia (OR=1.78; 99% CI, 1.08-2.94), superimposed preeclampsia (OR=3.64; 99% CI, 1.82-7.29), preterm birth (OR=1.81; 99% CI, 1.32-2.49), induction (OR=1.40; 99% CI, 1.06-1.86) and ICU admission (OR=3.70; 99% CI, 1.16-11.80).

These findings highlight a need for further research to determine whether women with appropriate treatment have a greater risk for developing pregnancy complications caused by the disease or whether treatment can stop adverse outcomes.

Disclosure: The researchers report no relevant financial disclosures.

    Perspective

    The strengths of this study include its large sample size, diverse population and the large number of covariates. However, the lack of thyroid function and antithyroid antibody measurements and the lack of information about treatment of thyroid dysfunction are important limitations. The treatment of pregnant women with overt hyperthyroidism and overt hypothyroidism is known to improve both obstetric and fetal outcomes. Currently, however, it remains unclear whether or not there is a benefit to diagnosing and treating pregnant women with subclinical hypothyroidism. Results of previous studies examining the effects of subclinical hypothyroidism on pregnancy outcomes have been inconsistent, with some, but not all, showing associations with adverse outcomes such as placental abruption and preterm delivery.

    Prospective studies are needed to better understand obstetric outcomes in subclinical hypothyroid women and whether these are improved with levothyroxine therapy.

    • Elizabeth N. Pearce, MD, MSc
    • Associate Professor of Medicine Boston University School of Medicine

    Disclosures: Pearce reports no relevant financial disclosures.