Hypothyroidism in pregnancy
Having hypothyroidism, or an underactive thyroid gland, requires changes to medication and close monitoring throughout pregnancy and afterwards. With the right treatment, you should be able to expect a healthy baby and a healthy you right up to term, and whichever mode of delivery is right for you.
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What are the risks in pregnancy?
Thyroid hormones are vital to keep you well and for the development of your growing baby, especially their brain and nervous system. Pregnancy pushes thyroxine levels down, so you will need your levothyroxine dose increased. Levothyroxine is safe to take during pregnancy and breastfeeding - take it on an empty stomach and at a different time to any vitamin or mineral supplements you are taking.
Unfortunately, if thyroid function is not kept under tight control, it does carry risks to you and your baby, including pre-eclampsia, miscarriage or stillbirth, preterm birth (before 37 weeks), low birth weight, birth defects, and problems with the baby’s physical and mental development. It may cause an underactive thyroid in the baby.
Your doctor will refer you to a hospital specialist, or endocrinologist, as soon as pregnancy is confirmed, and they will monitor you closely.
Should I do anything before getting pregnant?
To start with, good control of thyroid function is essential for fertility in both men and women. The earlier you seek advice, the better. Ask your doctor for a thyroid function test when you’re planning to conceive, to optimise treatment according to your levels for your forthcoming pregnancy.
Form a plan in advance with your doctor about increasing your levothyroxine once you know you are pregnant. Once you know you are pregnant, let them know so they can organise further blood tests at the start of pregnancy. They will refer you to an endocrinologist for further monitoring.
Does pregnancy make thyroid function worse or better?
As pregnancy reduces levels of thyroxine, hypothyroidism would get worse through pregnancy if the dose of levothyroxine wasn’t increased from the start, and if it wasn’t changed in response to blood tests throughout. Levels usually stabilise in the later stages of pregnancy, so your specialist may decide to reduce the frequency of blood tests from the initial four to six weeks.
Most women return to pre-pregnancy thyroid function after birth – your thyroid should be checked around six weeks after delivery and medications may be adjusted then.
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