Key Points Question Are abnormal preconception thyrotropin levels associated with adverse maternal and fetal outcomes? Findings In this populational-based cohort study of over 5.8 million Chinese women, both low and high maternal preconception thyrotropin levels were associated with higher risk of preterm birth, small for gestational age, and perinatal infant death. Meaning In this study, both low and high maternal thyrotropin levels were associated with a significantly increased risk of adverse pregnancy outcomes; the optimal preconception thyrotropin levels may be between 0.37 mIU/L and 2.50 mIU/L.

IMPORTANCE Abundant evidence suggests thyroid dysfunction is associated with adverse pregnancy outcomes. However, associations of preconception thyrotropin levels outside of reference range with reproductive health outcomes are not well characterized. OBJECTIVE To evaluate the associations of preconception thyrotropin levels with time to pregnancy (TTP) and risk of spontaneous abortion (SA).

Background Inconsistent results were found in the association between serum alanine aminotransferase (ALT) and hypertension among population-based studies. This study evaluated the association between ALT and hypertension among Chinese reproductive-age population by utilizing registration data from National Free Pre-pregnancy Checkups Project in 2016–2017. Methods The 21,103,790 registered participants were eligible for analysis, including women who were 20–49 years old and men who were 20–59 years old with available data for ALT and blood pressure (BP). Logistic regression was conducted to estimate odds ratio (OR) for the association between ALT and hypertension as a binary outcome. Linear regression was used to examine the association between ALT and BP as a continuous outcome. Results In total, 4.21% of the participants were hypertensive, and 11.67% had elevated ALT (> 40 U/L). Hypertension prevalence was 3.63% and 8.56% among participants with normal and elevated ALT levels. A strong linear relationship was found between serum ALT levels and the odds of hypertension after adjustment for potential confounders. The multivariable-adjusted ORs for hypertension were 1, 1.22 (1.21, 1.22), 1.67 (1.65 1.68), 1.78 (1.76, 1.80), and 1.92 (1.90, 1.94) in participants with ALT levels of ≤ 20, 20.01–40, 40.01–60, 60.01–80, and > 80 U/L, respectively. Systolic and diastolic BPs rose by 1.83 and 1.20 mmHg on average, for each 20 U/L increase in ALT (P for trend < 0.001). The association was consistent among subgroups and tended to be stronger among populations who are overweight (body mass index ≥ 24 kg/m2) (χ2 = 52,228, P < 0.001), alcohol drinking (χ2 = 100,730, P < 0.001) and cigarette smoking (χ2 = 105,347, P < 0.001). Conclusions Our cross-sectional analysis suggested a linear association between serum ALT and hypertension or BP, which indicated that abnormal liver metabolism marked by elevated serum ALT could play a role in hypertension or elevated BP condition.