Abortion may be associated with elevated risk of future hypothyroidism.

OBJECTIVE

Fetal microchimerism during pregnancy and abortion has been linked with autoimmune hypothyroidism in females. We conducted a case-control study to investigate the odds of "abortion in the past" in the newly diagnosed hypothyroid females compared to their age-matched euthyroid controls.

METHODS

All consecutive newly diagnosed hypothyroid females, over 1 year, were enrolled as cases. Age-matched euthyroid controls were selected from the same region. The exposure variable tested was "past history of abortion (elective or therapeutic)."

RESULTS

Totally, 120 cases and 172 controls were recruited over 1 year with a mean age of 42.2 ± 9.8 years and 41.1 ± 12.4 years, respectively. The exposure variable (abortion) was present in 71 (59%) cases and 10 (6%) controls. Odds ratio (OR): 23.5 (12.2-48.9) < 0.0001. Autoimmunity, based on thyroid peroxidase (TPO) positivity (TPO levels ≥30 U/ml), was present in 92 (77%) of the cases; TPO was negative in 28 (33%) of cases. The exposure variable was documented in 62.4% and 50% of TPO positive and negative cases, respectively ( = 0.28).

DISCUSSION AND CONCLUSION

The study suggests that abortion (elective or therapeutic) in the past is strongly associated with newly diagnosed hypothyroidism in females aged 42.2 ± 9.8 years; OR: 23.5 ( < 0.0001). Interestingly, abortion was associated with both, TPO positive and negative hypothyroidism.