Hashimoto’s thyroiditis (HT) and pregnancy are linked in many ways. On the one hand, Hashimoto’s is the most common autoimmune disease in the US, and pregnancy is one of the factors that can lead to it. Studies have shown that around 20% of women who have thyroid issues during their pregnancy will go on to develop HT.
However, it also works the opposite way. Inadequate thyroid function due to HT can play havoc with the hormones that are responsible for fertility and successful pregnancies. If you’ve been trying to conceive, it is important to understand the process of conception and how HT can impact it.
There are a number of hormones involved in conception and a successful pregnancy.
Estrogen helps control a woman’s cycle and allows the lining of the uterus to thicken so that a fertilized egg can become implanted and grow for 9 months. The pituitary gland controls estrogen. Lower estrogen levels in the body signal no baby, and a period will start. The process of increasing and decreasing estrogen will continue the following month.
Follicle Stimulating Hormone (FSH)
FSH causes the follicles in the ovaries to grow and start to secrete estrogen. One follicle will be prepared. This will signal that the lining of the uterus should take place to get ready for the fertilized egg.
Luteinizing Hormone (LH)
At the time when a woman ovulates, around day 14 of her menstrual cycle, a large burst of LH is released. The prepared follicle will release an egg into one or the other of the Fallopian tubes, giving it the chance to be fertilized.
Once the follicle releases the egg, it becomes an empty sac known as the corpus luteum. But it still has work to do, secreting large amounts of progesterone. Progesterone helps prepare the lining of the uterus for a fertilized egg.
Human Chorionic Gonadatropin (HCG)
If the egg is fertilized, HCG is released and supports the corpus luteum as it produces more hormones to keep the lining of the uterus healthy to maintain the pregnancy. At the end of about 2 months, a placenta will form, and it will take over the production of progesterone.
A fine balancing act
As you can see, 5 hormones and other substances all contribute to a healthy pregnancy. If anything goes wrong with any one of those 5 aspects, however, there will be problems with conception, or maintaining a healthy pregnancy.
Since women are 5 to 8 times more likely than men to get thyroid conditions, it is clear there is some link to female hormone, which means your thyroid can affect your ability to become pregnant and have a healthy baby.
A slow thyroid can increase a hormone called prolactin, which lowers LH secretion, triggering less ability to detect progesterone and less sensitivity to FSH in the follicle. The sum total is a problem with ovulation, so there will be problems with fertility.
Birth control pills have been shown to have a significant impact on thyroid health. It is possible that they can disrupt significantly the communication between the hormones even after you stop taking them.
Thyroid issues also cause ovarian health issues, in particular FSH and LH levels. These can cause miscarriage, mood changes and migraines at the end of each period.
What to do if you have HT
If you think you have HT, see your doctor for thyroid hormone testing. If you get a definitive diagnosis of having a slow thyroid, see an endocrinologist to develop an effective treatment plan based on your current state of health and your future plans.
If you are trying for a baby, have your thyroid tested beforehand. It could save you countless months, years and dollars.
If you do test positive for HT, you should learn all you can about HT so you can have a healthy pregnancy.