Thyroid health before and during pregnancy

[Writer] This is Sharon Parmet with UIC News at the University of Illinois at Chicago. I spoke with Dr. Marla Barkoff, assistant professor of clinical medicine in the department of endocrinology, diabetes and metabolism about thyroid health and how the health of the thyroid impacts ability to get pregnant and the course of the pregnancy. Here’s Dr. Barkoff.

[Barkoff] When I talk to patients about the thyroid I explain that it is essentially the motor of the body. And in some situations the motor can speed up some people have hyperthyroidism, or the motor can slow down and cause hypothyroidism. And this motor essentially affects multiple parts of the body from the brain to the gut to the muscles. It affects people’s energy as well, so the thyroid is essentially the motor that secretes thyroid hormone that controls all of these other various systems in the body.

Symptoms of hypothyroidism for everyone to know would be progressive fatigue, depressed mood, constipation and this may just be hard stool or less frequent stool, dry skin, feeling very cold and that is compared to other people they live with or work with. Certainly in Chicago people are cold in the winter, but I often ask in comparison to other people. Certainly women any changes in their menstruation or their menstrual cycles would be a possible need to evaluate the thyroid. That’s all the symptoms of the motor slowing down. Conversely, the symptoms of the motor becoming faster is what we see in hyperthyroidism. Women or men can feel tremulous or shaky, or they may find that their signature or handwriting has become more sloppy. People tend to feel hot compared to other people and report a lot of sweating. Weight loss is often seen when people are hyperthyroid and we can see weight loss of often 50 plus pounds in people who are hyperthyroid. Conversely I will say the weight gain contributed purely to hypothyroidism is much more mild. So the weight gain attributed purely to thyroid disease can be in the order of ten to fifteen pounds. While the weight loss we see with hyperthyroidism can be much more significant. Other symptoms of hyperthyroidism can be frequent, loose stools, feeling more anxious or more jittery as well.

In a non-pregnant state, we talk a lot about the symptoms of being hypothyroid or not having enough thyroid hormone. This could cause someone to be tired, depressed, it is essentially the motor slowing down, so think about the gut slowing down it causes constipation. The brain and the mood slowing down, we just talked about fatigue and depression. It can cause the skin to be dry, the hair to be thin and brittle. It can affect women’s menstrual cycles as well. There can be an associated iron deficiency with hypothyroidism as well. So essentially the motor is slowing down and people feel pretty lousy because of that. In pregnancy we worry about the mom being hypothyroid because in the first trimester the baby doesn’t have a thyroid that is functioning. The baby’s thyroid develops about 11 or 12 weeks in pregnancy and efficiently starts making thyroid hormone at about 14 weeks which is the beginning of the second trimester now. So essentially the whole first trimester, the baby doesn’t have a thyroid, but requires thyroid hormone for critical development mostly neurologic or brain development. The baby is dependent on the mom’s thyroid working perfectly to pass that thyroid hormone from the mom through the placenta to the baby. If the mom’s thyroid hormone isn’t balanced, there are a lot of risks that can be posed to the baby’s development. 2 10 87

We know that if the mom’s thyroid hormone is not well balanced before conception that she often runs into problems when she tries to conceive and in that first trimester. If the mom is hypothyroid and is not well managed there is increased risk of miscarriage. If the pregnancy progresses past the first trimester, there is still increased risk of preterm delivery. The data shows that a TSH level of above 2.5 in the first trimester is associated with increase miscarriage. We do our best to optimize the mom’s thyroid right before she gets pregnant. Pregnancy is a stress test to the thyroid. In women who have a normal underlying thyroid they can often meet the demands of pregnancy. The thyroid has to increase its thyroid hormone production by about 30 to 50 percent this is the mom’s thyroid in the first trimester of pregnancy. One of the reasons is that the baby is now demanding this thyroid hormone, so the mother has to make more. Another reason is that there is increased filter load to the kidneys during pregnancy and so mom can essentially filter out some of her iodine during pregnancy and requires iodine supplementation. We can talk about that in a bit. To make sure that the mom has the building blocks to make the more thyroid hormone that she needs. In women that don’t have a normal thyroid at baseline they often fail the stress test in pregnancy and become hypothyroid and that could essentially make the baby hypothyroid and lead to the consequences of poor neurologic development as severe as permanent mental retardation or more on the mild spectrum a learning disability and cognitive delay.

We’re working on a study now; it is a joint collaboration with endocrinology and reproductive endocrinology which is the division of obstetrics and gynecology here at UIC. There’s a lot of collaborative interest in understanding how invitro fertilization can impact the mom’s thyroid access. And when I say thyroid access, I mean thyroid status and her thyroid hormone production. Prior to embryo transfer, women often undergo a three week period of what is called controlled ovarian hyper stimulation which uses multiple hormones which can affect the women’s thyroid status.

The majority of literature looking at mom’s thyroid during the invitro fertilization process comes out of Italy. And it is clear that at the beginning of the hormonal preparation and at the time of embryo transfer the mother’s thyroid status can be significantly affected. Notably one third of women who start the process with a TSH less than 2.5 will cross that magical TSH of 2.5 threshold during the IVF process.

What we have recently looked at is population which is more diverse than the homogenous European populations. Our population includes white Americans, black Americans, and we use the categorization of Hispanic in our population that we are studying because this is how patients self-identify. The African-American population and Hispanic population in the U.S. are not well studied in terms of thyroid affects during pregnancy especially under-represented in the endocrinology literature.

And what we know clinically is that during the three week time period prior to embryo transfer the thyroid status needs to be followed very closely in women who have pre-existing thyroid disease because at the time of embryo transfer we want to set the environment up in the women’s body up for success. I also follow closely in between embryo transfer and the first pregnancy test and then I often follow after the first pregnancy test and every two to four weeks in the first trimester. The American thyroid association guidelines recommend monitoring women with pre-existing thyroid disease every four weeks in the first trimester, but in my clinical experience in women participating in invitro fertilization four weeks is too long of time to wait in between lab values. And so I often monitor every week between the beginning of controlled ovarian hyper stimulation and embryo transfer and then often every two weeks in the first trimester.

In a non-pregnant state, that’s the time that I love meeting patients because that gives me the opportunity to educate and to counsel when we’re not in kind of crisis mode of the patient who is already pregnant. I certainly see patients who present to me pregnant, but I love to see patients who have a thyroid disease prior to pregnancy so I can go through all of the counseling and education and set their pregnancy up for success.

[Writer] Dr. Marla Barkoff is assistant professor of clinical medicine in the department of endocrinology, diabetes and metabolism in the UIC College of Medicine. This has been a podcast from UIC News at the University of Illinois at Chicago. For more information on UIC visit www.uic.edu.