Association between isolated hypothyroxinaemia in early pregnancy and perinatal outcomes

Abstract

Background The effect of isolated maternal hypothyroxinaemia (IMH) on pregnancy complications and neonatal outcomes in human beings is still controversial. Methods This was a retrospective cohort study based on the electronic medical register system. The records of women with a singleton pregnancy who sought antenatal examination between January 2014 and December 2015 at Shanghai First Maternity and Infant Hospital were extracted from the electronic medical records system. Thyroid-stimulating hormone (TSH), free thyroxine (fT4) and anti-thyroperoxidase autoantibody (TPO-Ab) was measured before 20 gestational weeks, and a multiple logistic regression model was used to estimate the odds ratios of pregnancy complications and neonatal outcomes between euthyroid women and those with isolated hypothyroxinaemia. Results A total of 8173 women were included in this study, of whom 342 (4.18%) were diagnosed with IMH. Regression analysis showed that IMH diagnosed in the second trimester (13–20 weeks) was associated with an increased risk of hypertensive disorders of pregnancy (OR = 2.66, 95% CI: 1.38–5.10) and placenta abruption (OR = 3.64, 95% CI: 1.07–12.41), but not with preterm delivery (OR = 1.09, 95% CI: 0.50–2.40), small or large gestational age of infant (OR = 0.91, 95% CI: 0.39–2.12; OR = 1.16, 95% CI: 0.72–1.86), macrosomia (OR = 1.71, 95% CI: 0.95–3.07), gestational diabetes mellitus (OR = 1.36, 95% CI: 0.86–2.15) and placenta previa (OR = 1.62, 95% CI: 0.39–7.37). Conclusion IMH could be a risk factor for hypertensive disorders of pregnancy.

Isolated Maternal Hypothyroxinemia and Adverse Pregnancy Outcomes: A Systematic Review

“…The articles were published in various geographical region: North America (15) and USA (14,20)], South America [Brazil (16)], Europe [Netherland (21,24,29), Spain (22), Finland (23) and Ireland (28)] and Asia / Australia [China (6,11,26,27) and Australia (25)]. All studies were prospective or retrospective cohorts and 47% (7/15) had a population-based design (21-23, 26, 27, 29, 30).…”

“…Nine studies investigated the association of maternal IMH and gestational HTN, preeclampsia and eclampsia (6,11,14,16,20,(23)(24)(25)28). Neither preeclampsia nor eclampsia were associated with IMH diagnosed in rst or second trimesters of pregnancy; in addition, all the above studies except for two (6,11) found no signi cant association between maternal IMH and gestational HTN. Gong et al (2019) however reported that IMH identi ed in the second trimester was associated with increased risk of only gestational HTN, particularly among women with BMI < 25 kg/m 2 , (adjusted OR: 4.2, 95% CI: 1.61-10.96) (6).…”

“…Gong et al (2019) however reported that IMH identi ed in the second trimester was associated with increased risk of only gestational HTN, particularly among women with BMI < 25 kg/m 2 , (adjusted OR: 4.2, 95% CI: 1.61-10.96) (6). Moreover, Su et al (2019), showed that IMH was associated with a 2.2-fold increased risk of gestational HTN (adjusted OR: 2.2, 95% CI: 1.28-3.82) (11). Of 8 studies (6,11,14,16,20,23,25,28) that assessed the association between maternal IMH and placenta abruption, all except one (28), showed no association between IMH and placenta abruption.…”

“…Moreover, Su et al (2019), showed that IMH was associated with a 2.2-fold increased risk of gestational HTN (adjusted OR: 2.2, 95% CI: 1.28-3.82) (11). Of 8 studies (6,11,14,16,20,23,25,28) that assessed the association between maternal IMH and placenta abruption, all except one (28), showed no association between IMH and placenta abruption. Two studies assessed the risk of breech presentation in mothers with IMH (6,29) and one (29) reported increased risk of breech presentation in women diagnosed with IMH in the rst trimester of pregnancy (adjusted OR: 4.7, 95% CI: 1.1-19).…”

“…Among studies included, 6 examined the association between IMH and macrosomia (6,11,14,20,26,28); 50% of these studies showed positive associations, indicating that the IMH diagnosed in the rst (20), second (6) and < 20 weeks of gestation (11) was associated with around 1.5-fold increased risk of macrosomia. Furthermore, 2 other studies showed an increased risk of LGA and among IMH women in the second trimester (OR: 2.088, 95% CI: 1.193-3.654) (27) and signi cant higher birthweight (22) in the rst half of pregnancy.…”