Perinatal risk factors for congenital hypothyroidism

Abstract

Congenital hypothyroidism (CH) is one of the most common neonatal endocrine diseases. This retrospective cohort study aimed to identify the potential perinatal risk factors for CH and to differentiate between transient and permanent CH (TCH and PCH, respectively) as well as determine their prevalence in a southeastern Chinese population. This study was based on an 18-year surveillance of a neonatal CH screening program in a large tertiary hospital. A retrospective review of the maternal and neonatal perinatal exposures was conducted. Of the 205,834 newborns screened between 2000 and 2018, 189 were diagnosed with CH (1/1089). Among the 131 CH patients who again underwent thyroid function testing (TFT) after discontinuation of levothyroxine at the age of 3 years, 61 (46.6%) were diagnosed with PCH and 70 (53.4%) were diagnosed with TCH. In the maternal characteristics model, women aged 35 years or older and those who had thyroid disease and/or diabetes mellitus during pregnancy had increased risk of having an offspring with CH (P = .001, .000, and .001, respectively). Significant associations were found with regard to parity and the risk of CH in the offspring (P = .000). In the neonatal characteristics model, infants with female sex, preterm birth, post-term birth, low birth weight, other birth defects, and those born as part of multiple births (P = .011, .034, .001, .000, .000, and .003, respectively) had increased risk of CH. The rate of newborns with other birth defects was higher in the PCH group than that in the TCH group (P = .008), whereas the rate of maternal thyroid disease, newborns with low birth weight, and newborns with preterm birth was higher in the TCH group than that in the PCH group (P = .041, .020, and .013, respectively). The levothyroxine dose (μg/kg/day) at 1 year, 2 years, and 3 years old was significantly lower in the TCH group than that in the PCH group (P = .000, .000, and .000, respectively). Perinatal factors should be considered during the diagnosis and treatment of CH.

A Systematic Review on the Risk Factors of Congenital Hypothyroidism

“…By considering the reported group differences, we could design more studies for better understand- ing of different subgroups of CH. As mentioned previously, though there were studies regarding CH-related risk factors (6,34,36,44,47,49,56,59,63) there was no comprehensive review in this field. Moreover, for some important risk factors such as seasonality or gender differences, the results of studies were not in agreement.…”

“…Some of the reported risk factors, including environmental pollutants (25,58), dietary component of mothers during prenatal period (41,64), neonatal jaundice (47), maternal anemia (48), intrauterine growth retardation (6), lower weight gain during pregnancy (60), urbanization (62), parental occupation and education (35,47), gestational diabetes (6,46,59), and smoking (14,47,60) have limited evidence. It seems that more studies for investigating the association of the mentioned risk factors with CH are necessary.…”

Prevalence and predictive factors of transient and permanent congenital hypothyroidism in Fars province, Iran

“…The last study in Fars province (2007) reported 53.6 % permanent CH cases [ 29 ]. Worldwide, 66.44 % of CH cases in the state of Alabama (USA) [ 25 ], 70.6 % in the state of Oregon (USA)[ 26 ], 75 % in the state of Michigan (USA)[ 22 ], 62 % in France [ 31 ], and finally, 46.6 % of CH cases in China were permanent; while the rest were transient [ 32 ]. In our study, 66.04 % had confirmed permanent CH, while only 33.96 % had transient CH.…”

“…Effects of parental consanguinity and familial history of thyroid disorders on transient and permanent CH is controversial. While studies by Rabbiosi et al, Dorreh et al, and Saba et al, found first-degree familial thyroid disorders more prevalent in permanent CH patients [ 24 , 34 , 35 ], Zhou et al, found them to be more prevalent in transient CH [ 32 ]. In our study, we did not find any statistical differences in the prevalence of familial thyroid disorders between the two groups, although it should be noted that both were higher than the general population.…”

“…Association between TSH serum concentration level at screening tests and the venous sampling with transient vs. permanent CH were inconsistent. Many studies found TSH serum concentration level at screening and the first venous sampling to be significantly higher in permanent CH [ 17 , 19 , 24 , 32 , 35 ]; while only a few studies found no significant difference between the two groups. [ 34 , 36 ] We found TSH serum concentration level > 43.35 mIU/L in the venous sampling (initial TSH) with the sensitivity of 31.66 % and specificity of 90.32 % to be the best cutoff point among the three TSH measurements in this study.…”