Are Babies Born via In Vitro Fertilization at Risk for Subclinical Hypothyroidism?
In many parts of the world, assisted reproductive technology is used. But there is growing concern about morbidity in babies born via in vitro fertilization (IVF). The majority of research done on this topic has been focused on mechanical conditions that can be attributed to multiple births.
Recently, Turkish researchers aimed to examine the impact IVF has on thyroid function in newborns.
Results of their findings were published online in late December 2011in the article “Subclinical hypothyroidism in in vitro fertilization babies.” It will be published soon in the journal Acta Paediatrica.
For this study, 98 healthy, term newborns who were born via IVF were assessed between 2 and 4 weeks old. The research team screened these newborns’ thyroid function between July 2006 and April 2008.
A total of 10 study participants were found to have thyroid-stimulating hormone (TSH) levels that were higher than 6.5 mU/L; these patients became part of a study group.
The control group included 10 infants who were naturally conceived. These infants were the same age as the infants in the study group, but they had hyperthyrotropinemia—which means they had TSH levels that were greater than 6.5 mU/L but less than 15 mU/L. Infants in the control group were randomly selected.
All of the children in the study had a thorough examination. In addition, the following levels were measured in all study participants in both groups:
- anti-thyroglobulin antibodies
- anti-thyroid peroxidase
- serum free T4
Also, researchers gave thyrotropin-releasing hormone (TRH) tests to all participants.
Researchers found that about 10% of the IVF babies had euthyroid hyperthyrotropinemia. For all IVF babies with subclinical hypothyroidism, exaggerated TSH levels to TRH were observed; however, they were not observed in the control group participants.
At the end of the study, the research team found a significant difference in the concentration of TSH at the 20th minute between the 2 groups (p<0.001). Additionally, sustained and delayed TSH responses were observed in the IVF babies, and neonatal screening tests were negative in both groups.
The researchers determined that despite normal neonatal screening tests in the in vitro fertilization babies, subclinical hypothyroidism may be observed, and so they recommend that IVF babies be screened for thyroid function.