Hashimoto’s disease (chronic autoimmune thyroiditis) is the most common cause of hypothyroidism in iodine-sufficient areas of the world. Autoantibodies directed against thyroid cells and tissue result in destruction of parts of the gland, and a consequent hypothyroid state, with reduced levels of thyroid hormones in the bloodstream. Though many women will proceed through their pregnancy with little or no complications, Hashimoto’s does present some special considerations for those who are pregnant. Below we consider the issue of pre-term delivery in the context of maternal Hashimoto’s disease.
What is the risk of preterm (less than 38 weeks) delivery if I have Hashimoto’s? What is the average length of pregnancy for mothers with Hashimoto’s?
As with many things in medicine and pregnancy, this risk is quite individualized and patient-dependent. Some women will have little risk, while others, owing to their Hashimoto’s severity and other precipitating factors, may be at considerable risk. Accordingly, some research has shown an increased potential for early delivery, while others have demonstrated no such findings. Such studies have yielded mixed results in terms of separating overt from sub-clinical disease.
However, it is generally agreed upon that uncontrolled disease can lead to adverse pregnancy outcomes, including preterm birth and accompanying low birth weight, which is a reason that women suspected of being hypothyroid should be screened and treated as soon as possible.
One review noted that proper treatment substantially lowered the chances of premature delivery, in both overt and sub-clinical scenarios, resulting in a majority of full term births without complications. While there appears to be little general consensus regarding these risks or related pregnancy term lengths, the NIH states that some studies have shown as much as a three-fold increase in preterm deliveries in women with hypothyroidism during pregnancy.
What issues are associated with preterm delivery? Are the majority of pre-term delivery babies healthy?
There are a host of possible complications seen in conjunction with preterm delivery, especially in terms of both acute and chronic problems for the newborn/infant. Some of these include issues with the respiratory, gastrointestinal, nervous and immune systems in the near term (including vision and hearing dysfunction; and possible cognitive, developmental, psychological or behavioral consequences later in life. The American Pregnancy Association offers a very clear and concise listing of major obstetrical and neonatal complications that may occur when a neonate is born before 39-41 weeks. Many such issues, even in late preterm deliveries, arise from the fact that the final weeks of pregnancy are essential for complete development of the fetus’ organ systems.
Unfortunately, even slightly preterm babies are susceptible to significantly greater problems than those born at full term, though this risk decreases as the length of pregnancy increases.
This is not to say that preterm babies are destined for complications, but they do tend to develop more problems than their full-term counterparts. Having said this, modern advances in medicine have made the chances of minimizing and/or overcoming these obstacles quite a bit greater than in years past.
What are the options for reducing the risk of pre-term delivery (e.g., bed rest, scheduled c-section, etc.)?
There are many possible recommendations your doctor may make in the interest of reducing this possibility, including such things as those indicated in the question above. But this is again best determined by your physician(s) based on individual circumstances and the most likely precipitating factors in your case. To be certain though, one thing that will help lower the chances of preterm birth and many other associated adverse outcomes, is proper and prompt treatment of the patient’s hypothyroid state, through the use of hormone replacement therapy. Removing or significantly decreasing this contributing factor will naturally raise the chances for a more positive outcome.
Specifically, expectant mothers who are concerned about the possibility of preterm birth (especially if they have a prior history of such) can help reduce the chances of this happening by seeking early prenatal care, eating a healthy diet, gaining weight properly over time, and avoiding certain risky substances (alcohol, cigarettes, illicit drugs) or strenuous behavior.
Additionally, if your physician feels there is significant risk of preterm birth, he or she may elect to use special medications to help delay the birth (such as various forms of progesterone) or speed up development of fetal organ systems (such as steroids, which are used to hasten completion of fetal lung development prior to delivery).
Control of chronic conditions unrelated to the pregnancy can also help stem the advent of preterm labor, probably owing to the reduced stress this places on the mother and fetus.
There may be other things you should do or avoid, in terms of food, substances or activities, as well as certain medications to take or stop taking during this time. For this reason, as always, it is important that you consult your healthcare provider regarding the individual aspects of your disease, and what it means for your pregnancy.
Questions for your doctor:
- What are my chances for preterm delivery based on my clinical and lab findings?
- Which medications should I stop, and which should I start or continue if I am hypothyroid during pregnancy?
- What factors would cause you to consider a planned or emergency c-section?
- Do you have any statistics regarding the risk or preterm birth with Hashimoto’s, or the average length of pregnancy?
- Besides those listed above, what other non-medication steps could I take to maximize my chances of carrying to term?
About the Author
Dr. Rothbard is a professional medical writer and consultant based in New York City, specializing in medical education articles targeted at a variety of audiences, from children through clinicians. After leaving medicine, he worked as a biology and medical science educator for several years, before deciding to pursue writing full-time. He may be reached at [email protected].