Impact of TPOAb-negative maternal subclinical hypothyroidism in early pregnancy on adverse pregnancy outcomes

Abstract

Purpose: To investigate the effect of subclinical hypothyroidism on pregnancy outcomes of women early in their pregnancy with different thyroid-stimulating hormone levels and thyroid peroxidase antibody–negative status and to explore reasonable thyroid-stimulating hormone levels for subclinical hypothyroidism in early pregnancy. Methods: A total of 2378 women early in their pregnancy were studied retrospectively. The baseline characteristics were collected from medical records. Pregnancy outcomes were compared between the euthyroidism and subclinical hypothyroidism groups that were diagnosed by 2011 or 2017 American Thyroid Association guidelines. In addition, the effect of different maternal thyroid-stimulating hormone levels on adverse pregnancy outcomes was analyzed using binary logistic regression. Results: According to the 2011 American Thyroid Association diagnostic criteria of subclinical hypothyroidism, the prevalence of pregnancy outcomes was not significantly higher in the subclinical hypothyroidism group than in the euthyroidism group. However, pregnant women with subclinical hypothyroidism identified by the 2017 American Thyroid Association criteria had a higher risk of premature delivery (odds ratio = 3.93; 95% confidence interval = 1.22–12.64), gestational diabetes mellitus (odds ratio = 2.69; 95% confidence interval = 1.36–5.32), and gestational anemia (odds ratio = 3.28; 95% confidence interval = 1.60–6.75). Moreover, no differences in the prevalence of adverse pregnancy outcomes were observed between the mildly elevated thyroid-stimulating hormone group (2.5 < thyroid-stimulating hormone ⩽4.0 mIU/l) and the normal thyroid-stimulating hormone group (0.27 < thyroid-stimulating hormone ⩽2.5 mIU/l). The significantly elevated thyroid-stimulating hormone group (4.0 < thyroid-stimulating hormone < 10.0 mIU/l) had a higher prevalence of premature delivery, gestational diabetes mellitus, and gestational anemia than the normal thyroid-stimulating hormone group, even after controlling for potential confounding factors. Conclusion: A mildly elevated thyroid-stimulating hormone level or maternal subclinical hypothyroidism diagnosed by 2011 American Thyroid Association guidelines during early pregnancy in thyroid peroxidase antibody–negative women was not associated with adverse pregnancy outcomes. However, maternal subclinical hypothyroidism identified by the 2017 American Thyroid Association guidelines increased the risks of several adverse pregnancy outcomes in women untreated with levothyroxine. The 2017 American Thyroid Association guidelines could be more reasonable for the diagnosis of subclinical hypothyroidism in southern China.

Impact of thyroid hormone treatment on maternal pregnancy outcomes in women with subclinical hypothyroidism without TPOAb

“…The median (IQR range) gestational age at which LT4 was started was 13 (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) weeks, of whom 30.2% started treatment after 20 weeks of gestation. The starting dose of LT4 was 45.3 ± 16.3 ug / day.…”

“…Concerning PTB, we had too few cases in the SCH control group to perform a statistical analysis. Noteworthy is that in one of the two earlier mentioned Chinese studies on the impact of SCH, the 95% CI was large, indicating there were also few cases in that study (aOR 4.07 (95% CI: 1.26-13.14)) [10]. Moreover, in a systematic review and meta-analysis, the association between SCH and PTB was no longer signi cant after additional adjustment for TPOAb positivity either [9].…”

“…In the meta-analysis by Yang et al, no association between SCH and gestational anaemia was present (OR 1.55, 95% CI: 0.99-2.44), although it should be noted that the index of heterogeneity was high (I 2 of 83%), and that for the de nition of SCH old (2.5 mIU/L) and new (4.0 mIU/L) cut-off values for TSH were used [35]. In the study by Zhu et al, the risk of gestational anaemia was signi cantly higher in women with TSH levels >4.0 mIU/L (aOR 3.28 (95% CI: 1.60-6.75)) [10]. The underlying mechanisms explaining the association between anaemia and thyroid function remain unclear; a few studies have shown that iron de ciency might affect thyroid function due to an impaired e cacy of TPO activity as well as the conversion from T4 to T3 or on the Krüppel-like factor 9, an essential factor for erythroid maturation and T lymphopoiesis [36,37].…”

“…Moreover, evidence on the impact of SCH (with a serum TSH level > 4.0 mIU/L) on pregnancy outcomes is low and results con icting [6,8,9]. Only recently, a study including many pregnant women with SCH and no TAI was published [10]. In that study, a negative impact of SCH was present on pregnancy outcomes such as gestational diabetes (GDM), gestational anaemia and PTB, but not on gestational hypertension.…”

Effect of Bushen Antai recipe on pyroptosis mechanism of subclinical hypothyroidism decidual cells in early pregnancy

“…Thyroid hormone is a key hormone that promotes growth and development, neural differentiation and maturation, and maintains the normal metabolism of the body. A previous study has shown that untreated SH during pregnancy seriously threatens the health of the mother and the fetus ( 1 ). The nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is closely related to placental inflammation-related diseases, and its abnormal activation can lead to the activation of Caspase-1 and the maturation of gasdermin D (GSDMD), inducing pyroptosis and accompanying inflammatory response, disrupting the physiological balance of the maternal-fetal interface, and leading to the occurrence of various adverse pregnancy events ( 2 , 3 ).…”