Harmful effects of hypothyroidism on maternal and fetal health drive new guidelines for managing thyroid disease in pregnancy

ScienceDaily (July 25, 2011) — Emerging data clarifying the risks of insufficient thyroid activity during pregnancy on the health of the mother and fetus, and on the future intellectual development of the child, have led to new clinical guidelines for diagnosing and managing thyroid disease during this critical period. The guidelines, developed by an American Thyroid Association (ATA) expert task force, are presented in Thyroid, a peer-reviewed journal published by Mary Ann Liebert, Inc.See Also:Health & MedicineThyroid DiseaseHormone DisordersPregnancy and ChildbirthDiseases and ConditionsCancerGynecologyReferenceHypothyroidismHyperthyroidismThyroid hormoneThyroid

Clinical studies are producing critical data demonstrating the harmful effects not only of overt hypothyroidism and hyperthyroidism on pregnancy, but also of subclinical thyroid disease and maternal and fetal health. Ongoing research is clarifying the link between miscarriage and preterm delivery in women with normal thyroid function who are thyroid peroxidase antibody positive. Studies are also uncovering the long-term effects of postpartum thyroiditis.

"Pregnancy has a profound impact on the thyroid gland and thyroid function…. In essence, pregnancy is a stress test for the thyroid, resulting in hypothyroidism in women with limited thyroidal reserve or iodine deficiency," state Alex Stagnaro-Green, George Washington University School of Medicine and Health Sciences (Washington, DC), and coauthors representing the ATA task force.

Among the many specific recommendations detailed in the guidelines are the following: women with overt hypothyroidism or with subclinical hypothyroidism who are TPO antibody positive should be treated with oral levothyroxine; use of other thyroid preparations such as triiodothyronine or desiccated thyroid to treat maternal hypothyroidism is strongly recommended against; and women with subclinical hypothyroidism in pregnancy who are not initially treated should be monitored for progression to overt hypothyroidism with serum TSH and free T4 measurements about every 4 weeks until 16-20 weeks gestation and at least once between 26-32 weeks gestation.

The new clinical guidelines focus on several key areas in the diagnosis and management of thyroid disease during pregnancy and postpartum: thyroid function tests, hypothyroidism, thyrotoxicosis, iodine, thyroid antibodies and miscarriage/preterm delivery, thyroid nodules and cancer, postpartum thyroiditis, recommendations on screening for thyroid disease during pregnancy, and areas for future research.

"These important guidelines were developed by a panel of international experts representing the disciplines of endocrinology, obstetrics and gynecology, and nurse midwives. This broad representation of providers that care for pregnant women will significantly increase the impact of these guidelines and translation of findings from the most recent research to clinical practice," says Gregory A. Brent, MD, Professor of Medicine and Physiology, David Geffen School of Medicine at the University of California Los Angeles and President of the ATA.

"Thyroid disease in pregnancy is common, clinically important, and time-sensitive, and our knowledge about it is rapidly changing. This ATA Guideline will disseminate this new information both widely and rapidly to improve patient care, establish what we believe is optimal care for the pregnant woman and her unborn child, and drive future research to further improve our understanding and patient outcomes," says Richard T. Kloos, MD, Professor, The Ohio State University and Secretary/Chief Operating Officer of the ATA.

Email or share this story:

In pregnancy, diabetes-obesity combo a major red flag

ScienceDaily (July 25, 2011) — Type 2 diabetes and obesity in pregnancy is a daunting duo, according to new research published this month in The Journal of Maternal-Fetal and Neonatal Medicine. The study shows that both conditions independently contribute to higher risks, opening the door to a wide range of pregnancy, delivery and newborn complications.See Also:Health & MedicineDiabetesPregnancy and ChildbirthObesityDiseases and ConditionsPersonalized MedicineChronic IllnessLiving WellReferenceDiabetes mellitus type 2Birth weightStillbirthHyperglycemia

Study authors say the findings are important because obesity and type 2 diabetes are skyrocketing in women of childbearing age. A study in The Journal of the American Medical Association reports that between 2007 and 2008 the prevalence of obesity among adult women in the United States was more than 35 percent. A report from the Centers for Disease Control and Prevention states that approximately 11 percent of women above the age of 20 had diabetes in 2010.

Loralei Thornburg, M.D., senior study author and a high-risk pregnancy expert at the University of Rochester Medical Center, emphasizes that the research is needed now more than ever. "We've never seen the degree of obesity and type 2 diabetes in women that we are seeing right now, because for a very long time diabetes was a disease of an older population, so we rarely dealt with it in prenatal care. We hope this new knowledge will help physicians better understand and care for this rapidly expanding group of high-risk women."

While numerous studies have established that obesity, in the absence of diabetes, is associated with problems in pregnancy -- preterm birth, birth trauma, blood loss and a prolonged hospital stay, to name a few -- less is known about type 2 diabetes and what causes difficulties when the two conditions coexist. Researchers from Rochester wanted to determine if obesity alone accounts for the increased risks in this "dual-diagnosis" group, or if diabetes plays a role as well.

To determine the influence of obesity and type 2 diabetes when the conditions coexist in pregnancy, Thornburg and lead study author Kristin Knight, M.D., used clinical records and the hospital's birth certificate database to identify 213 pairs of women who delivered babies at the Medical Center between 2000 and 2008. Each pair included a diabetic and a non-diabetic patient with approximately the same pre-pregnancy body mass index (BMI). The majority of women in the study were overweight, obese or morbidly obese.

"We matched the pairs pound for pound, because if obesity was the main problem, we'd see similar outcomes between women, whether they had diabetes or not. But if we saw different outcomes between pairs, we'd know the diabetes was impacting outcomes as well," said Thornburg.

Using mathematical models and controlling for outside factors, such as age and tobacco use, researchers found that the patients with type 2 diabetes had overall worse pregnancy, delivery and newborn outcomes than their BMI-matched counterparts. Specifically, diabetic patients had higher rates of preeclampsia, cesarean delivery, shoulder dystocia, preterm delivery, large for gestational age infant, fetal anomaly and admission to the neonatal intensive care unit.

"Women and their physicians need to be aware that each condition on its own increases risk in pregnancy, so when they coexist the situation is even more worrisome," said Knight, a maternal fetal medicine fellow at Rochester. "Pregnancy is a time of great change, and fortunately many women are very open to making modifications during this period in their life. Anything a woman can do to improve her condition, from controlling blood sugar and exercising, to eating nutritious foods and maintaining an optimal weight, will help her deliver a healthier baby."

Knight originally focused her research on the effects of type 1 and type 2 diabetes on pregnancy. In a previous study, she found that women with type 2 diabetes, most of whom were also obese, had poorer outcomes. Consequently, her research turned to obese, type 2 diabetics and their experiences in pregnancy.

"If a woman enters pregnancy obese, but hasn't developed type 2 diabetes, she is in a better place than if she had both," concluded Thornburg.

In addition to Knight and Thornburg, Eva K. Pressman, M.D., and David N. Hackney, M.D., from the Medical Center, also participated in the research.

Email or share this story: