A Novel Nomogram for Predicting the Risk of Premature Delivery Based on the Thyroid Function in Pregnant Women

Abstract

BackgroundMaternal thyroid dysfunction and autoantibodies were associated with preterm delivery. However, recommendations for cutoff values of thyroperoxidase antibody (TPOAb) positivity and thyroid-stimulating homone (TSH) associated with premature delivery are lacking.ObjectiveTo identify the pregnancy-specific cutoff values for TPOAb positivity and TSH associated with preterm delivery. To develop a nomogram for the risk prediction of premature delivery based on maternal thyroid function in singleton pregnant women without pre-pregnancy complications.MethodsThis study included data from the International Peace Maternity and Child Care Health Hospital (IPMCH) in Shanghai, China, between January 2013 and December 2016. Added data between September 2019 and November 2019 as the test cohort. Youden’s index calculated the pregnancy-specific cutoff values for TPOAb positivity and TSH concentration. Univariate and multivariable logistic regression analysis were used to screen the risk factors of premature delivery. The nomogram was developed according to the regression coefficient of relevant variables. Discrimination and calibration of the model were assessed using the C-index, Hosmer-Lemeshow test, calibration curve and decision curve analysis.Results45,467 pregnant women were divided into the training and validation cohorts according to the ratio of 7: 3. The testing cohort included 727 participants. The pregnancy-specific cutoff values associated with the risk of premature delivery during the first trimester were 5.14 IU/mL for TPOAb positivity and 1.33 mU/L for TSH concentration. Multivariable logistic regression analysis showed that maternal age, history of premature delivery, elevated TSH concentration and TPOAb positivity in the early pregnancy, preeclampsia and gestational diabetes mellitus were risk factors of premature delivery. The C-index was 0.62 of the nomogram. Hosmer-Lemeshow test showed that the Chi-square value was 2.64 (P = 0.955 > 0.05). Decision curve analysis showed a positive net benefit. The calibration curves of three cohorts were shown to be in good agreement.ConclusionsWe identified the pregnancy-specific cutoff values for TPOAb positivity and TSH concentration associated with preterm delivery in singleton pregnant women without pre-pregnancy complications. We developed a nomogram to predict the occurrence of premature delivery based on thyroid function and other risk factors as a clinical decision-making tool.

Preconception Counseling in Patients with Hypothyroidism and/or Thyroid Autoimmunity

“…Even though the link between SCH and pregnancy loss or live birth has been previously denied [41], more recent large studies emphasized that pregnant women with SCH were at higher risk for miscarriage, preterm delivery, gestational diabetes, gestational hypertension, eclampsia, and premature rupture of membranes compared with euthyroid women, especially when TSH was >4 mU/L [32,[42][43][44][45][46][47]. Moreover, their offspring was more likely to have intrauterine growth restriction, low birth weight, to be admitted in neonatal intensive care unit and have respiratory distress syndrome [43,48].…”

“…On the other hand, there is increasing data regarding the association of thyroid dysfunction and thyroid autoimmunity with adverse pregnancy outcomes such as miscarriage, recurrent embryo implantation failure and preterm delivery [28,47,[71][72][73][74][75][76]. The higher risk of miscarriage could have multiple causes, including a relative thyroid hormone shortage, caused by a decreased thyroid functional capacity, an impaired thyroid response to human chorionic gonadotropin, or a higher general susceptibility to autoimmunity [77][78][79][80].…”