Table 1.
Characteristics of the included studies.
| Author | Year | Country | Study design | Gestational age at LT4 initiation | Group size | |
|---|---|---|---|---|---|---|
| Intervention | Placebo | |||||
| Ye W et al. (24) | 2019 | China | Cohort study | <14 weeks | 171 | 112 |
| Nazarpour S et al. (10) | 2018 | Iran | RCT | 11.4±4 weeks | 87 | 60 |
| Maraka S et al. (25) | 2017 | USA | Cohort study | NA | 513 | 697 |
| Casey BM et al. (23) | 2017 | USA | RCT | 8-20 weeks | 339 | 338 |
| Nazarpour S et al. (27) | 2017 | Iran | RCT | 10.8±4 weeks | 38 | 34 |
| Yang J et al. (26) | 2015 | China | Cohort study | <12 weeks | 1236 | 806 |
| Author | Year | SCH definition | Outcomes | Quality | ||
| Ye W et al. (24) | 2019 | TSH >4.0 mIU/L | Miscarriage, Gestational diabetes, Gestational hypertension, Preterm birth, Placental abruption, FGR, LGA | High | ||
| Nazarpour S et al. (10) | 2018 | TSH >4.0 mIU/L | Preterm delivery, Placental abruption, Stillbirth, Neonatal admission | High | ||
| Maraka S et al. (25) | 2017 | TSH 4.10-10.0mIU/L | Pregnancy loss, Preterm delivery, Preterm labor, PROM, Placental abruption, Gestational diabetes, Gestational hypertension, Preeclampsia, Poor fetal growth | High | ||
| Casey BM et al. (23) | 2017 | TSH >4.0 mIU/L | Preterm birth, Placental abruption, Gestational hypertension, Preeclampsia, Gestational diabetes, Stillbirth or miscarriage, Neonatal death, Admission to NICU, Birth weight <10%, Respiratory distress syndrome, Child IQ | High | ||
| Nazarpour S et al. (27) | 2017 | TSH >4.0 mIU/L | Preterm delivery, Neonatal admission, Miscarriage, Placental abruption, Stillbirth, Neonatal TSH levels | High | ||
| Yang J et al. (26) | 2015 | TSH 5.22-10.0mIU/L | Miscarriages, Preterm birth, Gestational hypertension, Gestational diabetes, FGR, LGA | High | ||
RCT, Randomized Controlled Trial; SCH, Subclinical Hypothyroidism; TSH, Thyroid Stimulating Hormone; FGR, Fetal Growth Restriction; LGA, Large for Gestational Age; PROM, Premature Rupture of Membrane; NICU, Neonatal Intensive Care Unit; IQ, Intelligence Quotient.