Management of hypothyroidism in pregnancy

The impact of levothyroxine exposure on delivery outcome in hypothyroid pregnant women (PETAL study): A five-year retrospective cohort study

Background

Hypothyroidism affects 3% of pregnant women, and to date, no studies have addressed the impact levothyroxine-treated hypothyroidism on delivery outcome.

Methods

This retrospective cohort study was conducted among 750 women with a singleton pregnancy who gave birth between 2015 and 2019. Delivery modes were compared between 250 hypothyroid women exposed to levothyroxine and 500 euthyroid control women. The aim of this study was to determine the impact of levothyroxine exposure on delivery outcome.

Results

Multiple logistic regression showed no significant association between exposure to levothyroxine and the overall rate of caesarean delivery (aOR 1.1; 95% CI 0.8 to 1.6). Mean TSH concentrations were significantly higher throughout the pregnancy in hypothyroid women despite levothyroxine treatment. Maternal and neonatal outcomes in both groups were not different.

Conclusion

Hypothyroidism treated with levothyroxine during pregnancy according to local guidelines is not a significant risk factor for caesarean delivery.

The Effects of Hydroalcoholic Extract of Nigella sativa Seeds on Serum Estradiol and Prolactin Levels and obstetric Criteria due to Hypothyroidism in Rat

Background:

The aim of this study was investigation of the effects of Nigella sativa (NS) seeds on hypothyroid pregnant rats and their progenies.

Materials and Methods:

Hypothyroidism was induced by propylthiouracil (PTU) 0.03% in drinking water. Female rats were divided into seven groups: control, PTU, PTU-NS (100, 200, and 400 mg/kg), and NS (100 and 400 mg/kg). All treatments were done 20 days before mating and during pregnancy. The weight of rat dams and progenies, number of progenies and serum T4, estradiol and prolactin (PRL) levels in rat dams were measured for all groups.

Results:

Serum T4 in all PTU-NS groups before mating was significantly increased versus PTU group. Body weight of rat dams before mating in all groups of PTU-NS was increased versus PTU group by P < 0.001, P < 0.05, and P < 0.001, respectively and in NS 100 and NS 400 was increased versus control group (P < 0.001). The number of offspring was significantly decreased in PTU and PTU-NS versus control group. The weight of progenies in NS 400 was higher than control group (P < 0.001) and was increased in PTU-NS 200 and PTU-NS 400 versus PTU group by P < 0.001 and P < 0.05, respectively. Serum PRL level in rat dams in control, PTU, and PTU-NS groups were not statistically different between groups but significantly increased in NS 400 group when compared to control group. Estradiol levels were not significantly different in rat dams at 5 days after delivery.

Conclusion:

These results demonstrated that feeding of rat dams with NS extract before mating has positive protective effects on progenies. These effects may be due to antioxidant properties of NS in reducing oxidative stress and thyroid damages induced by PTU.

Transient Maternal Hypothyroxinemia Potentiates the Transcriptional Response to Exogenous Thyroid Hormone in the Fetal Cerebral Cortex Before the Onset of Fetal Thyroid Function: A Messenger and MicroRNA Profiling Study

Thyroid hormone (TH) is essential for brain development both before and after birth. We have used gene expression microarrays to identify TH-regulated genes in the fetal cerebral cortex prior to the onset of fetal thyroid function to better understand the role of TH in early cortical development. TH levels were transiently manipulated in pregnant mice by treatment with goitrogens from gestational day (GD) 13-16 and/or by injection of TH 12 h before sacrifice on GD 16. The transcriptional response to exogenous TH in the GD 16 fetal cortex was potentiated by transient goitrogen treatment, suggesting that the hypothyroxinemic brain is a different substrate upon which TH can act, or that robust compensatory mechanisms are induced by transient hypothyroxinemia. Several known TH-responsive genes were identified including Klf9, and several novel TH-responsive genes such as Appbp2, Ppap2b, and Fgfr1op2 were identified in which TH response elements were confirmed. We also identified specific microRNAs whose expression in the fetal cortex was affected by TH treatment, and determined that Ppap2b and Klf9 are the target genes of miR-16 and miR-106, respectively. Thus, a complex redundant functional network appears to coordinate TH-mediated gene expression in the developing brain.

Pregnancy outcomes in women with severe hypothyroidism

OBJECTIVE

Hypothyroidism during pregnancy has been associated with adverse obstetrical outcomes. Most studies have focused on subjects with a mild or subclinical disorder. The aims of the present study were to determine the relative rate of severe thyroid dysfunction among pregnant women with hypothyroidism, identify related factors and analyse the impact on pregnancy outcomes.

DESIGN

A retrospective case series design was employed.

METHODS

The study group included 101 pregnant women (103 pregnancies) with an antenatal serum TSH level >20.0 mIU/l identified from the 2009-2010 computerised database of a health maintenance organisation. Data were collected from the medical records. Pregnancy outcomes were compared with those of a control group of 205 euthyroid pregnant women during the same period.

RESULTS

The study group accounted for 1.04% of all insured pregnant women with recorded hypothyroidism during the study period. Most cases had an autoimmune aetiology. All women were treated with levothyroxine (L-T₄) during pregnancy. Maximum serum TSH level measured was 20.11-150 mIU/l (median 32.95 mIU/l) and median serum TSH level 0.36-75.17 mIU/l (median 7.44 mIU/l). The mean duration of hypothyroidism during pregnancy was 21.2 ± 13.2 weeks (median 18.5 weeks); in 36 cases (34.9%), all TSH levels during pregnancy were elevated. Adverse pregnancy outcomes included abortions in 7.8% of the cases, premature deliveries in 2.9% and other complications in 14.6%, with no statistically significant differences from the control group. Median serum TSH level during pregnancy was positively correlated with the rate of abortions+premature deliveries and rate of all pregnancy-related complications (P<0.05).

CONCLUSIONS

Abortions and premature deliveries occur infrequently in women with severe hypothyroidism. Intense follow-up and L-T₄ treatment may improve pregnancy outcomes even when target TSH levels are not reached.

3,3'-Diiodothyronine sulfate cross-reactive material (compound W) in human newborns

BACKGROUND

Thyrosulfoconjugation appears to facilitate fetal-to-maternal transfer of 3,3'-diiodothyronine-sulfate (T(2)S). Elevated maternal levels of T(2)S cross-reactive material (compound W) are found in humans, with higher levels found in venous cord blood than in arterial samples. These findings are consistent with the postulate that the placenta plays an essential role in compound W production.

METHODS

Serum compound W levels were measured by a T(2)S-specific radioimmunoassay in 60 serum samples from newborns with hyperbilirubinemia, age 1-30 d. In addition, 59 maternal serum samples, from day 1 to day 7 after uneventful deliveries, were studied.

RESULTS

As compared with day 1, at day 5, the mean (±SE) compound W level fell to 43.5 ± 6.8% (decay half-life (t(1/2)) = 4.12 d) and to 33.7 ± 4.6% (decay t(1/2) = 2.82 d) in the newborn and maternal groups, respectively. In the mothers, the level continued to decline along the same slope through day 7. In the newborns, however, the mean compound W level entered a slower phase of decay after the fifth day with a decay t(1/2) = 10.9 d.

CONCLUSION

Compound W is cleared at similar rates in newborn and postpartum maternal sera. This is consistent with the postulate that compound W is produced in the placenta.

Severe hypothyroidism causing pre-eclampsia-like syndrome

Objective. Analyzing and managing pre-eclampsia-like syndrome due to severe hypothyroidism. Methods. Presentation of a case of severe hypothyroidism due to Hashimoto's syndrome, associated with a severe early-onset preeclampsia-like syndrome, managed in our Gynecology Department. Results. Severe pre-eclampsia led to miscarriage at 24 weeks of gestational age in a 42-year-old woman, although we attempted to correct hypothyroidism with increasing doses of levothyroxine and liothyronine sodium. Conclusion. Recognizing pre-eclampsia-like syndrome caused by overt hypothyroidism from other forms of pregnancy-induced hypertension is essential for choosing the correct treatment.