Association of thyroid dysfunction and autoantibody positivity with the risk of preterm birth: a hospital-based cohort study

Estimating the individual singleton preterm birth risk: nomogram establishment and independent validation

Background

To establish and independently validate nomograms for predicting singleton preterm birth (PTB) risk based on a large sample size comprising data from two independent datasets.

Methods

This cohort study used data from 50 states and the District of Columbia in the National Vital Statistics System (NVSS) database between January 2016 and December 2020. Multivariate logistic regression analysis was used to confirm the independent risk factors for PTB. Statistically significant variables were incorporated into the logistic regression models to establish PTB prediction nomograms. The models were developed using the United States (US)-derived data and were independently validated using data from US Territories.

Results

A total of 16,294,529 mother-newborn pairs from the US were included in the training set, and 54,708 mother-newborn pairs from the US Territories were included in the validation set. In all, 4 nomograms were built: 1 to predict PTB probability, and another 3 to predict moderately and late PTB probability, very PTB probability, and extremely PTB probability, respectively. Hypertensive eclampsia and infertility treatment were found to be the top 2 contributors to PTB.

Conclusions

We developed and validated nomograms to predict the individualized probability of PTB, which could be useful to physicians for improved early identification of PTB and in making individualized clinical decisions.

Association of Early Pregnancy Free and Total Triiodothyronine With the Subsequent Risk of Gestational Diabetes Mellitus

OBJECTIVE

To estimate the association of free triiodothyronine (FT3) and total triiodothyronine (TT3) in early pregnancy and subsequent gestational diabetes mellitus (GDM) risk and define appropriate TT3 thresholds for GDM screening.

METHODS

This investigation is a hospital-based cohort study of pregnant women submitted to a universal thyroid function test before 24 weeks of gestation. GDM was diagnosed according to a 75-g oral glucose tolerance test. The association of maternal high FT3 and TT3 levels in early pregnancy with the risk of GDM was estimated using logistic regression. The potential nonlinear association was probed by the restricted cubic spline curve method.

RESULTS

A total of 27 184 pregnant women and 3073 GDM cases were included in the analysis. FT3 and TT3 were associated with an increased subsequent risk of GDM in a nonlinear fashion. The adjusted odds ratios were 1.59 (95% confidence interval, 1.50-1.68) and 2.80 (95% confidence interval, 2.46-3.18) for FT3 and TT3 continuous levels, respectively. Associations were strong in euthyroid women, showed heterogeneity in women with mild thyroid dysfunction, and lacked in patients with overt hypothyroidism and hyperthyroidism. The TT3 thresholds of 1.5 and 2.0 ng/mL between 7 and 12 weeks of gestation and 1.6 and 2.1 ng/mL for 13 to 23 weeks of gestation effectively distinguished the subsequent risk of GDM.

CONCLUSION

The increased FT3 and TT3 levels in early pregnancy were associated with a subsequent higher risk of GDM. These findings provide measures for early detection and potential prevention of GDM.