Nav: Home

Should hypothyroidism in pregnancy be treated?

January 25, 2017

ROCHESTER, Minn. -- When a woman becomes pregnant, many changes occur in her body. One of those changes is in the levels of various hormones produced by the body.

In the case of thyroid-stimulating hormone (TSH), pregnant women typically produce a lower level than normal (0.4-4.0 milli-international units per liter). Some international guidelines recommend levels be no higher than 2.5-3. milli-international units per liter during pregnancy. When their TSH levels rise above this, they may experience subclinical hypothyroidism, or mildly underactive thyroid, which can cause a number of health problems if left untreated.

Today, Mayo Clinic researchers report that one of those results could be pregnancy loss. Researchers further suggest a course of action that could positively impact as many as 15 of every 100 pregnancies. In a study published in The BMJ, they show that treating subclinical hypothyroidism (not quite the level that would be treated in a nonpregnant woman) can reduce pregnancy loss, especially for those with TSH levels on the upper end of normal or higher.

"A recent analysis of 18 studies showed that pregnant women with untreated subclinical hypothyroidism are at higher risk for pregnancy loss, placental abruption, premature rupture of membranes, and neonatal death," says Spyridoula Maraka, M.D., an endocrinologist and lead author of the study. "It seemed likely that treating subclinical hypothyroidism would reduce the chance of these deadly occurrences. But we know that treatment brings other risks, so we wanted to find the point at which benefits outweighed risks."

Using the OptumLabs Data Warehouse, Dr. Maraka and her team examined the health information of 5,405 pregnant women diagnosed with subclinical hypothyroidism. Of these, 843 women, with an average pretreatment TSH concentration of 4.8 milli-international units per liter, were treated with thyroid hormone. The remaining 4,562, with an average pretreatment TSH concentration of 3.3 milli-international units per liter, were not treated.

Compared with the untreated group, treated women were 38 percent less likely to experience pregnancy loss. However, they were more likely to have a preterm delivery, or experience gestational diabetes or preeclampsia.

The team also looked at the levels of pretreatment TSH to determine if there was a point when treatment would have the most positive overall effect.

"Unsurprisingly, we found that women with higher levels of pre-treatment TSH--between 4.1 and 10 milli-international units per liter --benefitted most from treatment," says Dr. Maraka. "This group's much lower likelihood of experiencing pregnancy loss was what brought the average down - and creates a good argument for updated clinical guidelines."

The researchers found that, for women with lower levels of TSH (2.5-4.0 milli-international units per liter), the risk of gestational hypertension (which can lead to preeclampsia) was significantly higher for treated women than for untreated women. There was no difference between treated women who had the higher levels of TSH (4.1-10 milli-international units per liter) and untreated women.

"Our findings lead us to believe that overtreatment could be possible," says Juan Brito Campana, M.B.B.S., a Mayo Clinic endocrinologist and study co-author. "If the TSH levels are in that 2.5-4.0 [milli-international units per liter] range, it may be best to leave subclinical hypothyroidism untreated."

The team found no other adverse outcomes that appeared affected by different pretreatment TSH levels and subsequent thyroid hormone use.

Dr. Brito Campana further says that the association of levothyroxine therapy (drug used to treat hypothyroidism) and the risk of pregnancy-related adverse outcomes (e.g., preeclampsia or gestational diabetes) should be seen as preliminary findings and should call for additional studies evaluating the safety of levothyroxine therapy in pregnant women with subclinical hypothyroidism.

The results and recommendations in this study seem somewhat prophetic. On Jan. 6, 2017, the American Thyroid Association published updated care guidelines with treatment recommendations for women experiencing thyroid disease during pregnancy.

"These guidelines can help women and their doctors decide together what will be best for them," says Dr. Brito.

"We are pleased to see them and remain committed to further medical research and refinement of available information to assist in shared decision-making and improved health."
-end-
This research was made possible by the Mayo Clinic Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, using the OptumLabs Data Warehouse. This data consists of retrospective administrative claims data, including medical claims and eligibility information from a large national U.S. health insurance plan, as well as electronic health record data from a nationwide network of provider groups. It is a resource of OptumLabs, a collaborative research and innovation center cofounded by Mayo Clinic and Optum in 2013. The research was conducted in collaboration with Mayo Clinic's Knowledge and Evaluation Research Unit. This unit focuses much of its efforts on developing and validating shared decision aids across all of health care. Dr. Maraka is a research collaborator in the unit.

In addition to her work at Mayo Clinic, Dr. Maraka works in the Division of Endocrinology and Metabolism, Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, and the Central Arkansas Veterans Healthcare System, Little Rock, Arkansas.

About Mayo Clinic

Mayo Clinic is a nonprofit organization committed to clinical practice, education and research, providing expert, whole-person care to everyone who needs healing. For more information, visit http://www.mayoclinic.org/about-mayo-clinic or http://newsnetwork.mayoclinic.org/

Mayo Clinic

Related Pregnancy Articles:

Are women using e-cigarettes during preconception and/or pregnancy?
A new study of 1,365 racially/ethnically diverse, low-income pregnant women found that 4% reported e-cigarette use.
A better pregnancy test for whales
To determine whale pregnancy, researchers have relied on visual cues or hormone tests of blubber collected via darts, but the results were often inconclusive.
Cannabis use during pregnancy
The large health care system Kaiser Permanente Northern California provides universal screening for prenatal cannabis use in women during pregnancy by self-report and urine toxicology testing.
Questions and answers about cannabis use during pregnancy
A new study shows that women have many medical questions about the use of cannabis both before and during pregnancy, and during the postpartum period while breastfeeding.
The effect of taking antidepressants during pregnancy
Exposure to antidepressants during pregnancy and the first weeks of life can alter sensory processing well into adulthood, according to research in mice recently published in eNeuro.
Is ivermectin safe during pregnancy?
Is it safe to give ivermectin to pregnant women? To answer this question, researchers from the Barcelona Institute for Global Health (ISGlobal), an institution supported by 'la Caixa,' conducted a systematic review and meta-analysis of studies that reported cases of accidental exposure to the drug among pregnant women.
Going to sleep on your back in late pregnancy
This study looked at whether going to sleep on your back in the third trimester of pregnancy was associated with average lower birth weights.
Opioid use disorder in pregnancy: 5 things to know
Opioid use is increasing in pregnancy as well as the general population.
Medical imaging rates during pregnancy
Researchers looked at rates of medical imaging (CT, MRI, conventional x-rays, angiography, fluoroscopy and nuclear medicine) during pregnancy in this observational study that included nearly 3.5 million pregnant women in the United States and Canada from 1996 to 2016.
New research on diet and supplements during pregnancy and beyond
The foods and nutrients a woman consumes while pregnant have important health implications for her and her baby.
More Pregnancy News and Pregnancy Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Dispatch 3: Shared Immunity
More than a million people have caught Covid-19, and tens of thousands have died. But thousands more have survived and recovered. A week or so ago (aka, what feels like ten years in corona time) producer Molly Webster learned that many of those survivors possess a kind of superpower: antibodies trained to fight the virus. Not only that, they might be able to pass this power on to the people who are sick with corona, and still in the fight. Today we have the story of an experimental treatment that's popping up all over the country: convalescent plasma transfusion, a century-old procedure that some say may become one of our best weapons against this devastating, new disease.   If you have recovered from Covid-19 and want to donate plasma, national and local donation registries are gearing up to collect blood.  To sign up with the American Red Cross, a national organization that works in local communities, head here.  To find out more about the The National COVID-19 Convalescent Plasma Project, which we spoke about in our episode, including information on clinical trials or plasma donation projects in your community, go here.  And if you are in the greater New York City area, and want to donate convalescent plasma, head over to the New York Blood Center to sign up. Or, register with specific NYC hospitals here.   If you are sick with Covid-19, and are interested in participating in a clinical trial, or are looking for a plasma donor match, check in with your local hospital, university, or blood center for more; you can also find more information on trials at The National COVID-19 Convalescent Plasma Project. And lastly, Tatiana Prowell's tweet that tipped us off is here. This episode was reported by Molly Webster and produced by Pat Walters. Special thanks to Drs. Evan Bloch and Tim Byun, as well as the Albert Einstein College of Medicine.  Support Radiolab today at Radiolab.org/donate.