Well Women Guide to Pregnancy and the Thyroid
During pregnancy a great deal of hormonal and other changes occur and these in turn alter thyroid function. Thyroid function tests need to be interpreted with care as during this time they will be very different.
The two hormones responsible for altering thyroid function are Oestrogen and hCG, (human chorionic gonadotrophin) This is the hormone that is measured in a pregnancy test and raised levels are what show as a positive result in the test.
The volumes of hCG circulating in early pregnancy can cause TSH levels to be low. Oestrogen, however, increases the amount of thyroid binding proteins in the serum and this increases thyroid hormone levels as most thyroid hormones in the blood are bound to these proteins. Measurements of “free” hormone usually remain unchanged.
The size of the thyroid can increase and this is usually only minimal and not detectable under medical examination, however should there be a significant increase or unusual discomfort in the neck or when swallowing, then this should be reported and thyroid function tests performed.
During the first trimester, the baby is totally dependant upon its mother for thyroid hormone. After this time, the baby’s thyroid starts producing its own thyroid hormones. It must be mentioned though, that since the baby is dependant on its mother for nutritional intake, that iodine intake, being an important nutritional requirement to proper thyroid function, should be carefully maintained. The World Health Organisation recommends 200 mcg per day during pregnancy. This would be applicable for mothers who otherwise have a normal thyroid
What complications can occur during pregnancy? (Please bear in mind that complications generally apply to untreated Thyroid conditions or where the mother is unaware that she has a thyroid condition)
Hyperthyroidism (overactive thyroid)
Most cases of hyperthyroidism in pregnancy are caused by Graves disease, although very high levels of hCG (also associated with morning sickness) can cause transient hyperthyroidism. Severe morning sickness is called Hyperemesis Gravidarum and in some cases, mothers need to be hospitalised.
Since scanning for hyperthyroidism in pregnancy is not recommended, diagnosis will come from laboratory testing and family history
Those with pre existing Graves disease will require monitoring and symptoms are often aggravated during pregnancy. Poorly monitored Hyperthyroidism in pregnancy can lead to pre eclampsia and mothers are also susceptible to very severe hyperthyroidism known as Thyroid storm
Ironically, Graves disease can improve during the third trimester but can also get worse after the birth of the baby.
Can Hyperthyroidism and Graves Disease affect my baby?
Uncontrolled hyperthyroidism can cause fast heart beat (tachycardia) in the baby, babies that are small for gestational age, premature birth, stillbirth and sometimes congenital abnormalities.
This can be due to the following:
Uncontrolled Maternal Hyperthyroidism
High levels of TSI (thyroid stimulating immunoglobulins)
Graves disease is an autoimmune disease and caused by the production of anti-bodies that stimulate the thyroid gland and known as thyroid stimulating immunoglobulins. These anti-bodies are able to cross the placenta and affect the baby’s thyroid gland. Although it is rare and only seen in around 2 per cent of Graves disease related pregnancies, high levels of TSI’s have been known to cause either foetal or neonatal hyperthyroidism. However, this is generally only seen where TSI’s are very high in the mother. Mothers with existing Graves disease generally have their TSI levels checked in the third trimester.
It is very important to tell you doctor if you have or have ever had Graves disease and whether you are taking antithyroid drugs as these can cross the placenta. It is also important to tell the doctor if you have ever had radioactive iodine or surgery Your baby will need careful monitoring during your pregnancy to ensure foetal health is not affected.
Antithyroid drug therapy (ATD) can impair the baby’s thyroid and cause foetal goitre so minimal doses should be used to ensure foetal thyroid health. However, the benefits to the bay of treating a mother with Hyperthyroidism far outweighs the risks providing drug therapy is carefully monitored.
Should the hyperthyroidism be mild, then drug therapy will be avoided and just careful monitoring used provided mother and baby are well. When treatment is needed the object is to keep free T3 and free T4 levels on the high side or normal and on the lowest dose of ATD as possible (with Propylthiouracil PTU generally being the chosen drug), and is the preferable range to avoid the baby developing hypothyroidism or goitre and monitoring will be by monthly thyroid function tests. Mothers who can not tolerate ATD will sometimes have their thyroid removed by surgery and this is very rare due to the risks of surgery and anaesthesia to the mother and baby and is only used if no other alternative.
Radioactive iodine treatment will not be used due to its ability to cross the placenta and have a direct affect on the baby’s thyroid gland, thus destroying it and causing hypothyroidism.
Mothers on anti thyroid drugs (PTU) can also breastfeed but the baby will require careful monitoring.
Beta blockers can also be used to treat the symptoms of hyperthyroidism in pregnancy but are generally used sparingly as they can affect the growth of the baby and are not recommended long term during the pregnancy and are preferable only for significant symptoms of tremors and severe palpitations whilst anti-thyroid medication is being evaluated and until sufficiently controlled by it, so only in the short term should beta blockers be used.
Graves disease usually worsens after delivery especially in the first three months and higher doses of ATD’s will be required and close monitoring of thyroid function during this time.
Hypothyroidism (Underactive thyroid)
As we already know, the autoimmune condition, Hashimoto's Disease is the most common cause of hypothyroidism. Other causes are over treatment of an overactive condition. Please Click HERE to go to the Thyoid page to read about all the various causes and symptoms of both hyper and Hypo thyroid
There are various conditions associated with hypothyroidism in pregnancy, one of which is anaemia. Muscle pain and weakness, (myopathy), pre-eclamsia, placenta abnormalities and post partumn haemorrhage being the others, but usually only presenting a problem in those women with severe hypothyroidism.
Of course, severe untreated hypothyroidism in the mother could lead to congenital hypothyroidism in the infant which can cause brain development problems.
Women should ask for their TSH, T3 and T4 levels to be checked whether they have a thyroid condition or not and when planning a pregnancy, this may be something that should be considered before becoming pregnant. Women with a family history of hypothyroidism should ensure these tests are performed as a matter of course, even though they themselves may not be presenting any symptoms. It is important to get your TSH levels checked as early as possible in the pregnancy due to TSH levels rising.
Women who already have a thyroid condition should ensure their TSH, T3 and T4 levels are monitored during pregnancy, and as soon as pregnancy is confirmed, a visit to the GP to put plans in place for monitoring. Levothyroxine medication may have to be adjusted throughout the course of the pregnancy due to fluctuating levels and often this can mean an increase in dose by as much as 50 per cent. Levels should be checked every 6 weeks or every 4 weeks when dosage needs adjustment.
Your baby's only source of thyroid hormone is your thyroid medication so you must ensure that you take it daily and preferably at the same time every day. (In the morning on waking is a good time)
The only treatment required for hypothyroidism in pregnancy is medication in the form of thyroxine. However, since anaemia is commonplace is hypothyroid women, iron levels require careful monitoring in order to avoid severe anaemia.
Another point worth noting and of utmost importance is that supplements containing iron will impair the absorbtion of thyroid medication, so a large gap between dosage should be observed. E.g If you take your thyroid medication in the moring, leave at least 6 hours before taking an iron or multivitamin supplement containing iron.
After delivery, mothers can return to their normal dose of thyroxine but should be monitored for a while to ensure normal levels return.
Points to note
Women with an existing treated hypothyroid condition have no more chance of birth defects in their baby than anyone else. So, if you have been reading about things like low birth weight, low IQ, miscarriage, birth defects, still birth etc, it should be noted that this is only in women with untreated hypothyroidism who are unaware that they have the condition and where TSH tests have not been performed to identify this.
I had a miscarriage in June 1997 and my thyroid condition had not then been identified. I also suffered with gestational diabetes, high blood pressure and anaemia during my pregnancy in 1998 when the condition was still unidentified and therefore untreated. My daughter Niamh displays no signs of problems (thank God) and is as bright as a button.
Women with Hashimoto's disease are much more likely to suffer from gestational diabetes during their pregnancy or have blood sugar problems.
Gestational Diabetes
This is a condition diagnosed in pregnancy when blood or urine is taken for testing. Since urine is regularly assessed in pregnancy, the repeated presence of sugar may indicate gestational diabetes. A blood test will confirm this. High blood sugar levels are a sign of this condition.
What causes it?
Impaired glucose intolerance is something that many pregnant women experience during pregnancy due to the high level of hormones and hormonal changes. It is in the third trimester that the hormonal changes can cause a pregnant woman to become at risk.
Due to increased levels of various hormones a strain is put on the pancreas which needs to produce three times the normal amount of insulin in pregnancy to counteract the increasing blood sugar levels due to pregnancy hormones. However the pancreas may not be able to produce sufficient levels of insulin to counteract this rise and then blood sugar will continue to rise and Gestational diabetes will result.
Since diabetes can affect the developing baby by possibly causing birth defects and also contributing to increased growth of the baby in the womb due to a higher level of nutrition, the baby may be larger than normal at delivery which can cause problems to both mother and baby and more risks at delivery.
Also after the birth the baby will no longer be receiving nourishment from it's mother so the sudden drop in blood sugar can cause some problems for the baby.
Who is a risk of getting Gestational Diabetes?
Sufferers of Hashimoto's Disease and other Autoimmune Diseases
Constantly having the presence of glucose in your urine
Being overweight prior to pregnancy
Impaired glucose tolerance or fasting glucose
Family history of diabetes
Having given birth to previous large babies
Previous gestational diabetes
Polyhydramnios. A condition where the mother has too much amniotic fluid.
How will I know?
Women are now screened at 24+ weeks. High risk women will be screened earlier. This involves a glucose tolerance test where a sweet drink is consumed and about an hour later, a blood sample is taken. This checks as to how the glucose was metabolised by the body.
Can it be treated?
You will monitor your blood sugar yourself throughout the remaining weeks of your pregnancy. You will be given a blood glucose meter by your hospital or doctor and asked to test your blood several times a day by pricking your finger with a special lancet and putting a small drop of blood on a test strip which is then put into the meter.
The meter then reads the results which should be written in a specially provided book for inspection at anti natal and/or doctors visits. You may be referred to a special clinic who can monitor your diet and advise of what you can and can't eat to keep blood sugar as normal as possible. The midwife will also test your urine at each visit to check for ketones which is an acid indicating that your diabetes is not being properly controlled. It may be the case that diet alone will not be enogh to control it and insulin may be needed by injection. You will be shown how to do this yourself and will be closely monitored and advised regarding this procedure in case of hypoglycemia.
Symptoms of this include dizziness and fainting, feeling shaky, weakness, headaches, excessive sweating etc.
Should you feel like this, test your blood and drink some fruit juice or a soft drink and then after about 15 minutes, check your blood again.
If it is still low, take some more fruit juice or eat in advance of your next meal if it is some way off.
This should all be carefully recorded in your book.
I myself had gestational diabetes with my fourth pregnancy which was controlled with diet and I went on to have an 8 pound 1 oz baby, although my birth was medically managed due to the diabetes and high blood pressure. I also had an epidural as the stress of the delivery was pushing my blood pressure to an all time high. One week before she was due, they asked me to come in early and I refused. Fortunately, I went into labour that night.
Your blood pressure and any resulting rise will also need to be carefully monitored. Persistant high blood pressure may indicate that your baby may need to be delivered early and you may be asked to come in to hospital for bed rest. Foetal monitoring will also be a matter of course and expect to sit on a monitor for up to an hour while your babies heart is recorded.
What happens afer the birth?
Your baby's blood glucose will be tested at birth. With gestational diabetes there is an increased risk of jaundice in the baby. Treatment includes either feeding the baby regularly or light treatment where the baby is put under special lights that remove the pigment resposible for jaundice called bilirubin. Jaundice goes away quickly when these treatments are carried out.
My son, Sean had jaundice after he was born and this was eliminated with lots of feeding. I had to stay in hospital for 5 days during this time so that the staff could monitor him. I particularly remember my father saying "God, what a great sun tan he has!" and he nicknamed him "Golden Child"
Will the diabetes remain after my baby is born?
Normally your blood glucose levels will return to normal within 6 weeks post natal because the placenta is no longer present and producing hormones responsible for the disruption.
Your blood sugar will once again be checked at the hospital in the form of a glucose tolerance test around 6 weeks after delivery to ensure things have returned to normal.
However women who have had gestational diabetes have an increased risk of going on to develope type 2 diabetes in later life. You also have a much greater risk of devloping gestational diabetes with further pregnancies.
In these cases it would be a good idea to keep to a healthy diet reducing sugar in your diet, stopping smoking and maintaining a healthy body weight in order to reduce your risk in the future.
Never stop taking your thyroid medication as the baby needs thyroid hormone and it's only source of this is you. This also applies to breatfeeding. It is completely safe to breastfeed your baby when taking levothyroxine
Can my child develope Hashimoto's Disease?
Hashimoto's disease has been said to be hereditary but this is often not the case. It would not appear until the teenage years if this is the case. It is rare in newborn babies but occasionally this can happen and thyroid treatment will be required.
My cousin's baby was born without a thyroid gland and takes thyroid hormone for life. He is fine and developing well.
Thyroid and fertility
The thyroid has a big impact on fertility. It interferes with everything including your ability to become pregnant, maintain the pregnancy to full term, your health after delivery and of course the health of your baby.
It is not surprising that in view of this, I wonder how many miscarriages are due to undiagnosed thyroid conditions?
Also, how many women who are unable to get pregnant and go through years of expensive fertility treatments really have an undiagnosed thyroid condition that could be remedied with thyroxine medication?. Please click here to go the Fertility page.
What about complications during pregnancy itself?
Throid conditions can worsen pregnancy complications and morning sickness can be much more severe. Hair loss can be greater, tiredness and fatigue whilst considered normal in pregnancy, can be amplified to quite an extent.Thyroid conditions can cause foetal growth problems, anaemia during pregnancy and afterwards, pre-eclampsia, gestational diabetes, premature labour, still birth and development and retardation problems in the baby after delivery.
I had an undiagnosed Hashimoto's disease during my 4th pregnancy with my daughter, Niamh in June 1998. I was ill throughout the entire pregnancy from conception to delivery and afterwards. I had extreme fatigue, severe muscle pain (myopathy) accelerated hair loss, high blood pressure, gestational diabetes, anaemia just to name a few. I had to be closely monitored during the third trimester and constant foestal monitoring in the final weeks.
Needless to say, my labour was managed and I was unable to have much choice regarding a birth plan. My labour was long and drawn out, some 22 hours in duration culminating in the need for an epidural and foetal distress as well as my own high stress levels.
Also, whether this is relevent, a week prior to my miscarriage in June 1997, I suffered an extremely sore throat. Sore to the point where I could not swallow at all due to the pain. I developed a very high temperature which lasted a few days. Could this have been Thyroid storm? A week later I miscarried. After the miscarriage I was very ill and so fatigued I could not stand up or walk for months.
No interest was taken by the medical profession and it was deemed normal in the circumstances. Not at any time was a thyroid condition thought of.
What about after the birth? Symptoms such as tiredness hairloss and depression are ignored as doctors put it down to normal feelings after birth and the strain of being a new mother. Given this, how many cases of "post natal depression" are actually undiagnosed thyroid conditions?
Last but not least and no less important, thyroid conditions can cause breast feeding difficulties and poor milk supply.
There are many books covering this subject and one of the best is Mary Shomons "Thyroid Hormone Breakthrough"
Please click here to see Mary Shomons Book about successful pregnancy with a thyroid condition This book will help you understand the important information you need to become pregnant, have a healthy baby, stay healthy yourself, and breastfeed your baby successfully.
Most of all, when planning a pregnancy, make sure you get your TSH, T3 and T4 levels checked as part of the planning process, whether you have a thyroid condition or not and eliminate the worry at the start either by early diagnosis or confirmation so that you can enjoy a happy worry free pregnancy.
Please Click here to go to the thyroid page
Please Click here to go to the fertility page
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