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Hypothyroidism: A Woman’s Guide to Fertility and Pregnancy

Medically reviewed by Jason C. Baker, MD on February 17, 2016Written by Jill Eisnaugle on February 17, 2016
Hypothyroidism: A Woman’s Guide to Fertility and Pregnancy

A 2012 study in the Journal of Applied and Basic Medical Research found that 2 to 4 percent of childbearing age women have low thyroid hormone levels. This means there are a lot of women who are affected by the fertility issues caused by hypothyroidism. Keep reading to find out how having low thyroid hormone levels can lead to risks before, during, and after childbirth.

Pre-Pregnancy

Hypothyroidism and low thyroid hormone levels can affect many different aspects of menstruation and ovulation. Having low levels of thyroxine, or T4, or elevated thyroid-releasing hormone (TRH) leads to high prolactin levels. This can cause either no egg to release during ovulation or an irregular egg release and difficulty conceiving.

Hypothyroidism can also cause a shortened second half of the menstrual cycle. This may not allow a fertilized egg enough time to attach to the womb. It can also cause low basal body temperature, high thyroid peroxidase (TPO) antibodies, and ovarian cysts, which can lead to pregnancy loss or an inability to become pregnant.

You should have your thyroid-stimulating hormone (TSH) and T4 levels monitored prior to becoming pregnant. This is especially true if you have low thyroid hormones already or have had a miscarriage. High risk factors include a family history of thyroid problems or any other autoimmune disease. Tackling your hypothyroid symptoms early in the pregnancy planning stages allows for early treatment. This can lead to a more successful outcome.

Pregnancy

The symptoms of hypothyroidism are similar to early pregnancy symptoms. Hypothyroid symptoms in early pregnancy include:

  • extreme tiredness
  • weight gain
  • sensitivity to cold temperatures
  • muscle cramps
  • difficulty concentrating

The treatment of hypothyroidism in pregnancy is generally the same as prior to conception. However, it’s important to inform your doctor as soon as you become pregnant so you can receive the proper treatment and it can be adjusted if necessary. Your doctor will check your TSH lab values every four to six weeks to ensure your hormones are in the appropriate range. Your thyroid hormone requirements rise during pregnancy to support the baby and yourself. It’s also important to note that your prenatal vitamin contains iron and calcium, which can block how the body uses thyroid hormone replacement therapy. You can avoid this problem by taking your thyroid replacement medicine and prenatal vitamin four to five hours apart.

Your doctor will need to use special care to treat your hypothyroidism during your pregnancy. If not properly controlled, it can cause:

  • maternal anemia
  • increase in maternal blood pressure
  • miscarriage or stillbirth
  • low infant birth weight
  • premature birth

Uncontrolled symptoms can also impact your baby’s growth and brain development. 

Post-Pregnancy

After giving birth, postpartum thyroiditis is common. Women with autoimmune thyroid disease develop this complication more often. Postpartum thyroiditis commonly begins in the first three to six months after giving birth. This condition lasts several weeks to months. Some of the symptoms can be hard to distinguish from the struggles associated with becoming a new parent.

The symptoms of postpartum thyroiditis may occur in two stages:

  • In the first stage, your symptoms might look like hyperthyroidism. For example, you may be nervous, cranky, have a pounding heartbeat, sudden weight loss, trouble with heat, fatigue, or difficulty sleeping.
  • In the second stage, hypothyroid symptoms return. You may have no energy, trouble with cold temperatures, constipation, dry skin, aches and pains, and problems thinking clearly.

No two women are alike in how postpartum thyroiditis affects them. A higher risk for postpartum thyroiditis occurs in women with high-TPO antibodies in early pregnancy. This is due to a weakened immune system.

Hypothyroidism can also affect your milk production but with proper hormone replacement therapy, this problem often resolves.

The Takeaway

You should talk to your doctor if you’re trying to get pregnant and have underlying thyroid or autoimmune disease or prior pregnancy complications. Your doctor can order the appropriate tests and develop a healthy pregnancy plan. The earlier you can prepare, the better your chances are for a successful outcome. And don’t underestimate the importance of exercising regularly, eating healthily, and reducing your stress levels. 

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