Screening of Subclinical Hypothyroidism in Antenatal Women and its Impact on Pregnancy Outcomes

Article Information

Title: Screening of Subclinical Hypothyroidism in Antenatal Women and its Impact on Pregnancy Outcomes

Authors: Kashif Razzaq, Rabiah Anwar, Nusrat Noor, Amera Tariq, Ayesha Imran, Bushra Iftikhar, Sobia Anwar

Journal: Pakistan Armed Forces Medical Journal (PAFMJ)

HEC Recognition History

Category	From	To
Y	2024-10-01	2025-12-31
Y	2023-07-01	2024-09-30
Y	2021-07-01	2022-06-30
Y	2020-07-01	2021-06-30
Y	1900-01-01	2005-06-30

Publisher: Army Medical College, Rawalpindi.

Country: Pakistan

Year: 2022

Volume: 72

Issue: Supplementary 2

Language: English

DOI: 10.51253/pafmj.v72iSUPPL-2.5690

Keywords: PregnancyOutcomeSubclinical hypothyroidism

Abstract

Objectives: To screen subclinical hypothyroid cases in antenatal checkups and to assess the impact of this condition on the fetomaternal outcome.
Study Design: Prospective cohort study.
Place and Duration of Study: Department of Gynecology and Obstetrics, Pakistan Naval Ship Shifa Hospital Karachi Pakistan, from Jun 2019 to May 2020.
Methodology: During the study period, all singleton pregnant women with no comorbid, having booking visits during the first trimester of pregnancy were included. Three thousand four hundred fifty obstetric patients fulfilled the inclusion criteria. Their serum TSH and free T4 and T3 were sent along with routine antenatal investigations. Pregnancy specific first-trimester normal reference values of TSH (0.03-2.3µU/ml) and free T4 (0.8-1.8ng/dl) were used to classify pregnant women into euthyroid (controls) and overt and subclinical hypothyroid (cases). Comparison of antenatal complications (gestational diabetes, gesta tional hypertension, pre-eclampsia, and preterm labour), mode of delivery (vaginal delivery, cesarean section) and perinatal outcome (intrauterine growth restriction, intrauterine fetal death, low APGAR score at 5 min) was made among both the groups.Results: Hypothyroid women had significantly increased risk of gestational hypertension (RR= 4.795% CI=2.902 to 7.773, p&lt;0.0001), preeclampsia (RR=4.07, 95%CI=2.315 to 7.197, p&lt;0.0001), preterm delivery (RR= 4.1, 95% CI=2.128 to 7.89, p&lt;0.0001), cesarean section rate (RR=2.3611, 95% CI=1.7106 to 3.2591, p&lt;0.0001) and risk of IUGR (RR=8.000, 95% CI= 1.869 to 34.227,&nbsp;p=0.005) as compared to euthyroid women.Conclusion: Subclinical hypothyroidism is associated with gestational hypertension, pre-eclampsia, intrauterine growth restriction, preterm delivery and increased cesarean section rate.

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Research Objective

To screen subclinical hypothyroid cases in antenatal checkups and to assess the impact of this condition on the fetomaternal outcome.

Methodology

Prospective cohort study conducted at the Department of Gynecology and Obstetrics, Pakistan Naval Ship Shifa Hospital Karachi Pakistan, from June 2019 to May 2020. Included singleton pregnant women with no comorbidities having booking visits in the first trimester. Serum TSH, free T4, and T3 were measured. Pregnancy-specific first-trimester normal reference values for TSH (0.03-2.3µU/ml) and free T4 (0.8-1.8ng/dl) were used to classify women into euthyroid (controls) and overt/subclinical hypothyroid (cases). Antenatal complications, mode of delivery, and perinatal outcomes were compared between groups.

Methodology Flowchart

                        graph TD
    A["Recruit Singleton Pregnant Women in First Trimester"] --> B["Measure Serum TSH, Free T4, T3"];
    B --> C["Classify into Euthyroid, Overt Hypothyroid, Subclinical Hypothyroid"];
    C --> D["Follow up until Delivery"];
    D --> E["Assess Antenatal Complications, Mode of Delivery, Perinatal Outcomes"];
    E --> F["Compare Outcomes between Groups"];
    F --> G["Analyze Data and Draw Conclusions"];

Discussion

The study highlights the association between subclinical hypothyroidism and adverse pregnancy outcomes, including hypertensive disorders, preterm delivery, increased cesarean section rates, and IUGR. The prevalence of subclinical hypothyroidism in this study (4.58%) aligns with findings in other regions. The authors emphasize the importance of screening and treating thyroid disorders during pregnancy to improve outcomes.

Key Findings

Subclinical hypothyroidism was diagnosed in 4.58% of pregnant women. Hypothyroid women had a significantly increased risk of gestational hypertension (RR=4.7), pre-eclampsia (RR=4.07), preterm delivery (RR=4.1), cesarean section rate (RR=2.36), and intrauterine growth restriction (IUGR) (RR=8.00) compared to euthyroid women.

Conclusion

Subclinical hypothyroidism during pregnancy, particularly when detected in the first trimester, is associated with an increased risk of hypertensive disorders, preterm delivery, cesarean section, and intrauterine growth restriction. Screening and treatment of thyroid disorders are crucial for improving pregnancy outcomes.

Fact Check

- Subclinical hypothyroidism was found in 4.58% of the 3450 women who met the inclusion criteria.
- Gestational hypertension was significantly increased in hypothyroid women with a Relative Risk (RR) of 4.7 (p<0.0001).
- The cesarean section rate was significantly higher in subclinical hypothyroid women (53.125%) compared to euthyroid women (22.5%) (RR=2.3611, p<0.0001).

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