Subclinical Hypothyroidism and Accidental Hemorrhage

Abstract

Back ground: Subclinical hypothyroidism (SH) is defined by an elevated serum thyrotropin level and normal serum thyroxine concentration. While strong evidence clearly demonstrates that overt dysfunctions (hyper- or hypothyroidism) have deleterious effects on pregnancy outcome, subclinical disease, namely subclinical hypothyroidism, has still to be conclusively defined as a risk factor for adverse outcomes^., of those bad obstetric outcomes, placental abruption (PA) (accidental hemorrhage) is associated with underlying risk factors both jeopardizing trophoblast and vascular function. Subclinical hypothyroidism may relate to both conditions.   Aim of study: to prove the association between subclinical hypothyroidism and placental abruption(accidental hemorrhage)  in study group compared to  control group.

Setting:  a prospective case controlled study involves total 109 laboring women, who attended Al-Zahra teaching hospital at Annajaf city-Iraq between  March to September 2013.

Patients and methods:of total 109 women entered our study, 54 with normal labour and were regarded as control group and 55 with clinical diagnosis of placental abruption, after complete history and examination, blood sample withdrawn and thyroid function test, TSH, T3, T4, and free T4 were measured  using commercially available Minividas kits (biomerieux, France), Minividas was performed according to manufacturer instructions. The normal value for T3 was (0.95-2.23), T4 (60-120) and TSH (0.25-5) µIU/ml and freeT4 (0.76-2.24). Those who had high TSH and low T3, T4 and free T4 when compared to laboratory specific normal values, were diagnosed as clinical (overt) hypothyroidism, and were excluded from our study.  those who had high TSH but normal freeT4 thyroid hormone were diagnosed to have  subclinical hypothyroidism, those in whom all hormone values were within  normal limits were designated as euthyroid. Statistical analysis: These were used to accept or reject the statistical hypotheses, they include the followings: ANOVA test (F-test) and (chi square test). The comparison of significant (P-value) in any test were S= Significant difference (P? 0.05). Results:

Of total 109 participants 54 regarded as control while 55 were diagnosed clinically as cases of PA, there were no statistical significant difference between two groups in maternal age with mean maternal age of 27.92±5.42 SD and 27.49±6.58 SD for control and PA respectively,  low parity dominated the picture for both groups and although the ratio of those who were P0-P2 was higher in cases of PA 92.7% compared to control group 87.7%this did not reach statistical significance with P value of 0.09, most of our participants were urban and there were no statistical clinical significance between two groups with figures of 76.3% and 79.6% for PA and control groups respectively, but there was statistically significance difference in gestational age between our study groups with PA tends to occur at smaller gestational age 34.67 weeks±3.39 SD compared to control group 37.57 weeks±1.57 SD, surprisingly  there was nearly fourfold rise in incidence of SH in patients with PA compared to control group with ratio of 16.3% and 3.7% for PA and control group respectively. And again there was no statistical significance in identification of SH for those who were term or preterm  in PA group (17.6% vs 15.1%).

Discussion:  subclinical hypothyroidism was identified in 3.7% of the control  population tested, and this corresponds with all previous reports 2% to 5% in pregnant women. however, this ratio increased to 16.3%, 9/55 (nearly fourfold ) of cases diagnosed with clinical abruption a figure which was higher than reviewed  in previous reports of 2-3 fold rise incidence of placental abruption with subclinical hypothyroidism. This  results agree with  Casey and colleagues who  studied pregnancy complications with SH, who found that Significantly more placental abruptions (relative risk [RR], 3.0; 95% CI, 1.1-8.2), were found in the SH group, but disagree with Cleary-Goldman and colleagues who reported  on First and Second Trimester Evaluation of Risk (FASTER) trial, in which the researchers found no increased risk of placental abruption. Unlike Brian M. Casey, who found that  women with subclinical hypothyroidism were significantly older than control women³, in this study  there was no statistically significant difference in mean  maternal age between two  groups, there were also no significant differences in other demographic variables like residency and parity,however;  gestational age (GA) was significantly lower for cases PA,  but when gestational age  studied  in relation to placental abruption with SH at term and preterm gestational ages 3/17 vs 6/38 respectively, this failed  to reach statistical significance.

Conclusion:

1-SH is not uncommon condition among our laboring population

2-SH was found to increase fourfold risk of placental abruption in this study

3-maternal age, parity, residence all were insignificant confounders between control and PA group

4- placental abruption tends to occur at preterm gestational age but this failed to reach statistical significance for cases with SH in term and preterm GA.