Thyroid function and thyroid disorders during pregnancy: a review and care pathway

PURPOSE

To review the literature on thyroid function and thyroid disorders during pregnancy.

METHODS

A detailed literature research on MEDLINE, Cochrane library, EMBASE, NLH, ClinicalTrials.gov, and Google Scholar databases was done up to January 2018 with restriction to English language about articles regarding thyroid diseases and pregnancy.

RESULTS

Thyroid hormone deficiencies are known to be detrimental for the development of the fetus. In particular, the function of the central nervous system might be impaired, causing low intelligence quotient, and mental retardation. Overt and subclinical dysfunctions of the thyroid disease should be treated appropriately in pregnancy, aiming to maintain euthyroidism. Thyroxine (T4) replacement therapy should reduce thyrotropin (TSH) concentration to the recently suggested fixed upper limits of 2.5 mU/l (first and second trimester) and 3.0 mU/l (third trimester). Overt hyperthyroidism during pregnancy is relatively uncommon but needs prompt treatment due to the increased risk of preterm delivery, congenital malformations, and fetal death. The use of antithyroid drug (methimazole, propylthiouracil, carbimazole) is the first choice for treating overt hyperthyroidism, although they are not free of side effects. Subclinical hyperthyroidism tends to be asymptomatic and no pharmacological treatment is usually needed. Gestational transient hyperthyroidism is a self-limited non-autoimmune form of hyperthyroidism with negative antibody against TSH receptors, that is related to hCG-induced thyroid hormone secretion. The vast majority of these patients does not require antithyroid therapy, although administration of low doses of β-blocker may by useful in very symptomatic patients.

CONCLUSIONS

Normal maternal thyroid function is essential in pregnancy to avoid adverse maternal and fetal outcomes.

Adverse fetal outcome in road accidents: Injury mechanism study and injury criteria development in a pregnant woman finite element model

This study documents the development of adverse fetal outcome predictors dedicated to the analysis of road accidents involving pregnant women. To do so, a pre-existing whole body finite element model representative of a 50th percentile 26 weeks pregnant woman was used. A total of 8 accident scenarios were simulated with the model positioned on a sled. Each of these scenarios was associated to a risk of adverse fetal outcome based on results from real car crash investigations involving pregnant women from the literature. The use of airbags and accidents involving unbelted occupants were not considered in this study. Several adverse fetal outcome potential predictors were then evaluated with regard to their correlation to this risk of fetal injuries. Three predictors appeared strongly correlated to the risk of adverse fetal outcome: (1) the intra uterine pressure at the placenta fetal side area (r=0.92), (2) the fetal head acceleration (HIC) (r=0.99) and (3) area of utero-placental interface over a strain threshold (r=0.90). Finally, sensitivity analysis against slight variations of the simulation parameters was performed and assess robustness of these criteria.

Level of lactate in amniotic fluid and its relation to the use of oxytocin and adverse neonatal outcome

OBJECTIVE

To assess whether the frequency of adverse neonatal outcome at delivery is related to the level of lactate in amniotic fluid and to the use of oxytocin.

DESIGN

Prospective observational study.

SETTING

Soder Hospital, Stockholm, Sweden.

POPULATION

Seventy-four women in active labor with a gestational age ≥36 weeks and mixed parity.

METHODS

Levels of lactate in amniotic fluid were analyzed bedside from an intrauterine catheter every 30 min during labor. Deliveries were divided into groups with and without oxytocin.

MAIN OUTCOME MEASURES

The frequency of adverse neonatal outcome at delivery.

RESULT

Of the deliveries 13.5% (10/74) concluded with an adverse neonatal outcome. The levels of lactate in amniotic fluid increased during labor, more so in deliveries where oxytocin was used. In the group with an adverse neonatal outcome, the level of lactate in amniotic fluid was significantly higher in the final sample before delivery (p = 0.04). In 18 deliveries, stimulation with oxytocin was temporarily halted for at least 30 min due to overly stimulated labor contractions. A decreasing level of lactate in amniotic fluid was shown within a median 5%/30 min. In the group where the administration of oxytocin was halted, there was no adverse neonatal outcome.

CONCLUSION

The frequency of adverse neonatal outcome was associated with the level of lactate in amniotic fluid and with the use of oxytocin. The level of lactate in amniotic fluid may be an additional valuable tool when oxytocin is administered during labor.

The immunological basis of villitis of unknown etiology - review

Villitis of unknown etiology (VUE) represents a common placental inflammatory lesion, primarily, but not exclusively, identifiable T lymphocytes at term. Despite considerable evidence to contest that this simply represents a benign pathological finding, VUE remains a significantly undervalued diagnosis. Given its association with adverse pregnancy outcomes; including fetal growth restriction, preterm birth, and recurrent pregnancy loss, an increased awareness amongst clinician obstetricians is certainly warranted. The underlying immunopathogenesis of VUE remains uncertain. Despite initial theories that this represents an infectious placental lesion of undiagnosed pathogenic source, a more complex sequence of events involving the "breakdown" of maternal-fetal tolerance is emerging. Characterization of a unique inflammatory phenomenon in which both maternal and fetal T lymphocytes and Höfbauer cells interact has captivated particular research interest and has generated analogies to both the problems of allograft rejection and graft-versus-host disease (GvHD). Within the context of VUE, this review evaluates how disruption of the multidimensional immunological mechanisms underlying feto-maternal tolerance may permit abnormal lymphocyte infiltration into placental villi. We shall review the existing evidence for these events in VUE and outline areas of certain future interest.