Is There an Association between Life Events, Postnatal Depression and Thyroid Dysfunction in Thyroid Antibody Positive Women?

Background: Postnatal depression is more common in women positive for thyroid autoantibodies, independent of thyroid hormone dysfunction, but the basis of this association is unclear. Aims: The objective of the work reported here has been to investigate from data obtained from previously published research, a possible association between life events, postnatal depression and the development of thyroid dysfunction in women who are positive for thyroid autoantibodies. Method: A cohort of pregnant women whose thyroid antibody status was positive ( N = 115), was identified at antenatal booking (approximately 16 weeks). These, and a group of women negative for thyroid antibodies ( N = 123), were assessed for depression at six to eight weeks postpartum and then at 12, 20 and 28 weeks postpartum according to Research Diagnostic Criteria (RDC). The number and type of life events over the preceding year were also assessed at eight weeks postpartum using Paykel's Life Event Schedule. At four weekly intervals postpartum until six months, thyroid antibody levels and thyroid function (plasma T3 T4 and TSH) were measured. Results: As anticipated, the thyroid antibody status remained the same throughout the study, and there was no difference in the number or type of life events reported in the preceding year, between antibody positive and antibody negative women. Postnatal depression was associated with an excess of both total and negative life events, independent of thyroid antibody status or actual thyroid hormonal status. Women who developed thyroid dysfunction did not report an excess of life events (total, negative or neutral) in the preceding year. Conclusion: There was an excess of reported total and negative life events in women with postnatal depression, but this was independent of thyroid antibody status or function.