Authors: Mahjabeen N, Tarafdar MA.
Background: Hypothyroidism has a great impact on pregnancy. But there is a controversy about the maternal and perinatal outcomes of subclinical hypothyroidism (SCH). This study was placed to know the significant effects.
Methods and Materials: A descriptive longitudinal study was held in Z. H. Sikder Women’s Medical College & Hospital, Dhaka, Bangladesh. 400 pregnant women were included in this study with purposive sampling. All antenatal patients from booking visit at 1st trimester to delivery were monitored by serum TSH and serum FT4 levels in each trimester and fetal outcomes were also monitored. 200 pregnant women were diagnosed as subclinical hypothyroidism (SCH) with random screening of initial thyroid function tests. Another 200 pregnant women were euthyroid. The study period was 3 years, from January 2020 to December 2022. To evaluate the thyroid status, maternal serum samples were collected in each trimester, total three times. Maternal outcomes, which we studied, were gestational hypertension, gestational diabetes mellitus, maternal anemia, antepartum hemorrhage, postpartum hemorrhage, placental abruption, preterm delivery, premature rupture of membranes (PROM), caesarean deliveries; perinatal outcomes were low birth weight (LBW), intrauterine growth restriction (IUGR), low Apgar score, stillbirth, congenital anomaly and NICU admission.
Result: This study includes 400 pregnant women, among which 200 were euthyroid and 200 were with SCH. The mean age was 27.12 ± 0.05 years in pregnancy with euthyroid group and 26.31 ± 0.25 in pregnancy with SCH group. Among the pregnancy with euthyroid group, 141 women were nullipara and 59 women were nullipara. Among the pregnancy with SCH group, 87 women were nullipara and 113 women were nullipara. Serum TSH level was 4.44 ± 0.11 in 1st trimester, 4.74 ± 0.19 in 2nd trimester, 5.45 ± 0.17 in 3rd trimester. Serum free T4 level was 8.29 ± 0.13 in 1st trimester, 6.65 ± 0.15 in 2nd trimester, 6.67 ± 0.34 in 3rd trimester. In pregnancy with SCH group gestational hypertension, miscarriage, placental abruption and premature rupture of membranes (PROM) were significantly higher (p<0.001). Antepartum hemorrhage (APH), preterm delivery and Caesarian deliveries were also higher in this group (p<0.05). Among the neonatal outcomes, low birth weight and intrauterine growth restriction (IUGR) babies were more born in pregnancy with SCH group. Anti TPO antibody titer was significantly higher in pregnant women with SCH.
Conclusion: Subclinical hypothyroidism (SCH) is associated with increased risk of gestational hypertension, premature rupture of membranes (PROM), abruptio placentae and fetuses have more risk of IUGR and LBW. Therefore, routine maternal thyroid function test should be done to protect from adverse maternal and fetal outcome.
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