Hypothyroidism and pregnancy: still a controversial issue

Abstract

Subclinical hypothyroidism (SCH) in pregnancy is common, according to literature, affecting up to 15% of pregnancies. It still represents a controversy weather levothyroxine has beneficial effects on pregnancy outcomes. In this retrospective and prospective cohort study, we assessed fetal and maternal outcomes in women with known thyroid status pre-pregnancy, and hypothyroidism during pregnancy. We included 393 pregnant women, 90 (22.9%) diagnosed with overt and 303 with SCH (77.1%). A total of 94 (56%) had positive anti-TPO antibodies. Levothyroxine substitution across all observational periods was suboptimal, mostly during first trimester in both groups of patients (85.4%). There was a difference in the number of live births in favor of group with SCH (p = .004). Women with overt hypothyroidism were more likely to develop complications during pregnancy (RR = 1.153, 95%CI = 0.775 − 1.714) and had positive TPO-antibodies more often (p = .022). The only significant association was found between fetal outcomes in women with SCH and positive TPO-antibodies (p = .018), while positive Tg-antibodies did not affect the pregnancy outcomes of women with SCH. Moreover, no correlation was observed between outcomes and adequacy of levothyroxine substitution. These results indicate that TPO-antibody positivity could be the most important factor of pregnancy outcomes independent of the TSH levels or adequacy of levothyroxine therapy.

摘要

亚临床甲状腺功能减退（SCH）在妊娠期间很常见的, 据文献报道多达15%妊娠女性合并SCH。左旋甲状腺素是否能改善妊娠结局仍存在争议。在这项回顾性和前瞻性队列研究中, 我们评估了妊娠前已知甲状腺功能状况和妊娠期间甲状腺功能减退的女性的胎儿和母亲结局。我们纳入393名妊娠女性, 其中90名（22.9%）诊断为甲状腺功能减退, 303名（77.1%）诊断为SCH。共94例（56%）TPO抗体阳性。左旋甲状腺素替代在所有观察期内效果都不太理想, 两组患者主要在妊娠前三个月（85.4%）。在活产数上, SCH组优于对照组（p=.004）。甲状腺功能减退的女性在妊娠期间发生并发症的可能性更大(RR=1.153, 95%CI= 0.775-1.714), 且更容易合并TPO抗体的异常（p=.022）。唯一发现与胎儿结局具有显著相关性是SCH合并TPO抗体阳性（p=.018）, 而Tg抗体阳性并不影响SCH女性的妊娠结局。此外, 左旋甲状腺素替代与妊娠结局之间没有相关性。这些结果表明, TPO抗体阳性可能是独立于TSH水平或左旋甲状腺素治疗之外的影响妊娠结局的重要因素。

The Chinese abstracts are translated by Prof. Dr. Xiangyan Ruan and her team: Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.

Keywords:

• Overt hypothyroidism
• subclinical hypothyroidism
• pregnancy outcomes
• TPO-antibody
• Tg-antibody
• levothyroxine substitution

Disclosure statement

No potential conflict of interest was reported by the author(s).