Risk factors associated with congenital hypothyroidism: a case-control study in southeast Iran

Abstract

Background and aimCongenital hypothyroidism (CH) is known as one of the most common preventable cause of mental retardation. This study aimed to determine factors associated with CH in Iran.MethodsThis case-control study was conducted on 160 children under one year old in Zahedan in southeast Iran in 2016. The neonates who were born from March 1, 2015 to March 19, 2016 and had undergone a screening program for CH were the study population. The neonates with serum TSH > 10mIu/L and T4 < 6.5 or TSH > 30 mIu/L were considered as a case group. Each case was individually matched for sex, age at birth and place of residence with three neonates with normal TSH and T4 titers as a control group. Data was gathered using a standard checklist and analyzed using SPSS 20 and statistical tests, such as Chi-square and Fisher’s exact tests. Multivariable logistic regression analysis was also used to identify independent predictors of CH.ResultsAbout 25 of the 40 patients with CH (62.5%) were male who, in the univariate analysis, the following explanatory factors had no significant association with CH: history of parental consanguinity, type of delivery, weight at birth, height at birth, age of mother, sampling time, nationality, and birth season (p>0.05). Although, multivariate analysis showed no significant association between the studied factors and risk of CH (p>0.05), the likelihood of CH was greater among neonates born to consanguineous parents (AOR: 1.78, 95% CI: 0.82–3.89), those who were born to lower height at birth (AOR: 1.82, 95% CI: 0.85–3.91), neonates born to mothers younger than 18 years (AOR: 2.43, 95% CI: 0.57–10.29) and those who were born in the summer (AOR: 1.76, 95% CI: 0.57–5.44).ConclusionNone of the studied factors were predictors for CH. Since consanguineous marriages are frequent in the province, and it may be a major contributory factor, future studies should be conducted on the genetic causes.

Risk factors for transient and permanent congenital hypothyroidism: a population-based case-control study

“…This study showed no significant association between birth weight and transient or permanent CH, as shown by Khammarnia et al previously [ 26 ].…”

“…The incidence of permanent and transient CH was higher amongst neonates with short height as compared to neonates with normal height. Khammarnia and colleagues also showed similar results with a two-fold increased risk of CH among children with short height than those with normal height [ 26 ].…”

“…In this study, there was no relationship between maternal age and transient or permanent CH, similar to previous studies showing a lack of relationship between mother’s age and CH [ 14 ]. In contrast, Khammarnia and colleagues [ 26 ] showed that infants born to young mothers were at an increased risk of CH, Harris et al found that infants born to mothers aged 40 years or older had an increased risk of CH [ 1 ].…”

Maternal exposure to PM2.5 may increase the risk of congenital hypothyroidism in the offspring: a national database based study in China

“…Several studies indicated that CH was considered as one of the most common preventable causes of mental retardation [28]. Certain irreversible complications for infants, such as neurological damage, slow growth, delayed skeletal maturation and mental retardation might be caused in case of untimely treatment of CH [29–32]. Therefore, the exploration of additional CH risk factors, such as air pollution plays a crucial role in reducing the incidence of CH and improving the quality of life in the offspring.…”

Mapping the relative risk of congenital hypothyroidism incidence via spatial zero-inflated poisson model in Guilan Province, Iran

“…These studies investigated some risk factors of CH such as the type of delivery; weight, length, and head circumference at birth; iodine deficiency; mother's; birth season; sex; and postdate delivery. [ 1 9 10 11 12 13 14 ]…”