Objective Higher prevalence of CH among Iranian population necessitates review of risk factors and distribution of these factors among whole populations.
Method In Guilan province during years 2006 to 2010, neonatal screening for TSH was measured in 3–5 days after birth. All neonate with TSH level >= 5 mu/l refer to endocrinologist and serum TSH, T3, T4 were measured. Base on public health data and profiles, total number of newborns, gestational age, method of delivery, birth season and birth weight in whole population and for each of CH patients in addition of these data, their TSH measurements have been recorded.
Results During 5 years, 119701 neonates were screened and CH was confirmed in 10.8% (221) of the referral cases (prevalence = 1:542). No significant statistical difference was seen between gender, birth season among CH patients and source population. Low birth weight (31% vs 4.9% - p value < 0.01), Postdate delivery (1.4% vs 0.2% - p value < 0.01) and macrosomia (were more prevalent in CH. Odds of congenital hypothyroidism in a post-date delivery was 6.9 times of a term delivery. In low birth weight neonates odds of CH was 3.2 times of normal birth weight. Rate of NVD were higher in CH patients rather than source population (39.2% vs 29.2% - p value = 0.01).
Conclusion LBW, postdate delivery and macrosomia are risk factors of congenital hypothyroidism.