This study was conducted to analyze the role of TSH level and TPOAb status in early pregnancy and use this information in assessment of the risk of gestational diabetes mellitus at different weeks of gestation when the FT4 level is normal.

A total of 7,729 women with singleton pregnancies who were receiving antenatal care at Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine between December 2012 and March 2014 were included in the study. All these women underwent screening for thyroid function (TSH,FT4 and TPOAb) at the first antenatal visit and a 75 g oral glucose tolerance test at 24-28 weeks of gestation. The correlation between a combination of TSH level and TPOAb status and the risk of gestational diabetes mellitus was analyzed.

Criteria:

Inclusion Criteria:

1. ≤19+6 weeks of gestation at the first antenatal visit;
2. singleton pregnancy;
3. FT4 level is within the normal range;
4. TSH level is normal or beyond the normal range.

Exclusion Criteria:

1. age <18 years or >40 years;
2. thyroid disease history before pregnancy, e.g. hyperthyroidism, clinical hypothyroidism and malignant tumors of the thyroid, regardless of medication treatment is needed or not;
3. twin or multiple gestations;
4. diagnosed with diabetes mellitus before pregnancy, or fasting blood-glucose level ≥ 7.0 mmol/L or HbA1C≥6.5% at the first antenatal visit;
5. diseases causing abnormal glycometabolism or severe co-morbidities or diseases causing abnormal glycometabolism.

All the pregnant women who were receiving antenatal care at Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine were invited to participate in the study.Informed consents were obtained from all subjects.