Thyroid diseases and adverse pregnancy outcomes in a contemporary US cohort

Thyroid diseases are inconsistently reported to increase risk for pregnancy complications.

The objective of this study was to study pregnancy complications associated with common and uncommon thyroid diseases.

We analyzed singleton pregnancies (N = 223 512) from a retrospective US cohort, the Consortium on Safe Labor (2002-2008). Thyroid diseases and outcomes were derived from electronic medical records. Multivariable logistic regression with generalized estimating equations estimated adjusted odds ratios (ORs) with 99% confidence intervals (99% CI).

Hypertensive diseases, diabetes, preterm birth, cesarean sections, inductions, and intensive care unit (ICU) admissions were analyzed.

Primary hypothyroidism was associated with increased odds of 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 (prelabor, 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). Iatrogenic hypothyroidism was associated with increased odds 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). Hyperthyroidism was associated with increased odds of 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).

Thyroid diseases were associated with obstetrical, labor, and delivery complications. Although we lacked information on treatment during pregnancy, these nationwide data suggest either that there is a need for better thyroid disease management during pregnancy or that there may be an intrinsic aspect of thyroid disease that causes poor pregnancy outcomes.