According to a study reported on in the Journal of Clinical Endocrinology and Metabolism, when a woman being treated for hypothyroidism becomes pregnant, she should immediately increase her levothyroxine dose by two tablets per week, in order to maintain her thyroid function in the normal ("euthyroid") range. According to the study, the addition of two additional dosages per week can significantly reduces the risk of hypothyroidism in the mother. (Maternal hypothyroidism in early pregnancy is associated with an increased risk of miscarriage, and in developmental and cognitive delays and deficiencies in children.)In this study, the women began increasing their dosage at around 5 1/2 weeks of pregnancy. Interestingly, at that early point, 27% of the study participants already had a TSH level elevated above 5.0, indicative of hypothyroidism.
A subset of the women did end up getting too much thyroid medication, and required further adjustment. The researchers suggest that those who are more likely to end up slightly overdosed include women without a thyroid, those whose TSH level prior to pregnancy was less than 1.5, and those who are taking at least 100 mcg/day of levothyroxine prior to pregnancy.
The study emphasized the importance of early pregnancy detection and action on the part of the patients, writing: "In clinical practice, women do not typically seek obstetrical care before 8-12 weeks gestation. Thus, patients themselves must understand the importance of initial (levothyroxine) adjustment immediately upon a missed menstrual cycle and a positive home pregnancy test."
According to the researchers, increasing the levothyroxine dosage by approximately 30% -- two extra dosages weekly -- as soon as pregnancy is confirmed "significantly reduces the risk of maternal hypothyroidism throughout the first trimester. Monitoring thyroid function approximately once monthly is required through midpregnancy because a minority of patients may require subsequent L-T4 dose modifications to maintain appropriate TSH concentrations."
More Information on Thyroid Disease in Pregnancy
- Managing Thyroid Disease During and After Pregnancy: Guidelines
- Fertility, Infertility, Pregnancy & Thyroid Disease Information Center
- Pregnant with Hypothyroidism? Increase Your Medication!!!
- What Are The Normal TSH Ranges During Each Trimester of Pregnancy?
- Hypothyroidism and Pregnancy Guidelines for Thyroid Disease & Pregnancy: American Thyroid Association Issues Guidelines for Pregnant Women
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The implications of this boggles the mind.
I was st the OBGYN 2 weeks ago he suspected pregnancy as I was 2 months late. He sent me off for a blood test for pregnancy and with a script for prenatal vitamins. I am on levothyroxine he never once mentioned that if positive I should have my thyroid monitored closely. Unfortunately I am not pregnant must just be another thyroid issue but I am glad to now have this information.
i am 28 yrs old..i am known case of hashimoto,s thyroiditis with hypothyroidism,i have previous 2 induced abortions,now i am 5 wks pregnant…i am on 150 mcg thyroxin per day…..before pregnancy my tsh level was less than 1 ….should i increase thyroxine dose?
I am not sure this is correct. I have thyroid problems and when I became pregnant my OBGYN knew that, my clinical doctor knew that, I talked to both about it and none of them recommended this course of action. I live in the US, I went back home to Argentina (where doctors care about their patients a lot more than they do in the US), I saw another OBGYN, a nutricionist, I had an ultrasound, saw a regular doctor. I mentioned my thyroid problem to all of them, nobody said anything about increasing it, they did say I should test it and they did. I was 6 1/2 weeks pregnant at that time. I came back, waited a couple of weeks and had to almost threaten my OBGYN here to give me an order to test my thyroid. The first test was normal, the second one was elevated, they recommended to wait and get tested AGAIN, I did, still elevated. The doctor said that the big risk is in the second trimester and none of them seems as concerned as I am. Of course, doctors in this country tend to not a give a crap… but still… at least they are scared of malpractice lawsuits, and I swear I have been threatening with that like crazy!
The title of this article should not say “two extra PILLS” as the recommendation is “two extra DOSES”.