One hundred and forty (140) healthy Afro-Jamaican pregnant women attending antenatal clinic in the Department of Obstetrics, Gynecology and Child Health, University Hospital of the West Indies, Jamaica (WI) during the period May 2000 to February 2001 consented to participate in this study. Women with a history of thyroid disease, any medical illness, depression or substance abuse were excluded. The mean age was 27 years, parity varied from primigravidae to 4 live births and the mean length of gestation was 8 weeks at booking. A relatively large number of these mothers (67) had to be excluded (45 failed to keep their antenatal appointments, 5 had miscarriages, 4 had initial thyroid dysfunction, 7 had premature deliveries, 1 developed severe hypertension during pregnancy and 5 were delivered by cesarean section). Thus a total of 73 pregnant women completed this study.
This study was duly approved by the UWI/UHWI Ethics Committee.
Each mother was given a questionnaire at booking to obtain a clinical profile and relevant demographic data. The Zung self-rating depression scale (SDS) questionnaire was administered at 28 weeks gestation and at 6 weeks postpartum. A participant was considered to have no psychopathy if Zung was <50, minimal to mild depression if Zung score was 50–59, moderate to marked depression if Zung score was 60–69, and severe to extreme depression if Zung score was 70 and over. Depending on the depression status, the cohort was subdivided into four subgroups (i) women depressed during prepartum only (ii) women depressed prepartum and who continued to be depressed postpartum (iii) women depressed postpartum only and (iv) women showing no signs of depression in either period.
Blood samples were collected at 8, 28, 35 weeks of gestation and at 1 day and six weeks after childbirth. Serum total thyroxine (TT4), free triiodothyronine (FT3), thyrotropin (TSH) were determined using standard radioimmunoassay kits (Diagnostic Products Corporation, Los Angeles, California, USA). The sensitivity value for each assay was 0.25 pg/dl; 0.2 pg/ml; and 0.03 :IU/ml, respectively. All samples for each test were assayed in the same batch.
Data are expressed as means ± SE or counts as appropriate. The data were analyzed by repeated measures analysis of variance (RMANOVA) with the between group factor being the four subgroups (i) women depressed during prepartum only (ii) women depressed prepartum and who continued to be depressed postpartum (iii) women depressed postpartum only and (iv) women showing no signs of depression in either period and the measurements done over time (8 wks 28 wks 35 wks 1 day postpartum and 6 wks postpartum) as the repeated measures factor. In analyses where there were significant interactions between the group factor and the repeated measures factor, we compared differences between the depression categories at each experiment and differences between the means of measured variables within each clinical category at each experiment, by Tukey method. In these comparisons the error term was the root mean square error from the RMANOVA analysis with its associated degrees of freedom.
The Zung self-rating depression scale (SDS) was used to classify participants into depression categories. For this analysis these categories were treated as an ordinal scale. To assess effects of changing thyroid hormones on the odds of changing depression categories postpartum we used only the measurements done at 28 wk prepartum and 6 weeks postpartum. We assessed the odds of being in a particular depressed category in the postpartum period for participants using an ordinal logistic model adjusting for prepartum depression category and differences in thyroid hormones level (6 wk postpartum – wk 28 prepartum values) as covariate. Inferential tests were considered statistically significant if p < 0.05 (two tail).
Data analysis was performed using Stata version8 for Windows (Statacorp, College station, TX).