Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 50 11 2012 11 15 735 739 EN Setila Dalili Guilan Health Center, Guilan University of Medical Sciences, Guilan, Iran. Seyed Mahmood Rezvany Guilan Health Center, Guilan University of Medical Sciences, Guilan, Iran. Arsalan Dadashi Guilan Health Center, Guilan University of Medical Sciences, Guilan, Iran. Abdolreza Medghalchi Guilan Health Center, Guilan University of Medical Sciences, Guilan, Iran. Hamid Mohammadi Department of Pediatrics, Shiraz University of Medical Sciences, Shiraz, Iran. Hosein Dalili Department of Pediatrics, Breastfeeding Research Center, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran. Mostafa Mirzanejad Guilan Health Center, Guilan University of Medical Sciences, Guilan, Iran. Hajar Gholamnezhad Guilan Health Center, Guilan University of Medical Sciences, Guilan, Iran. Anis Amirhakimi Department of Pediatrics, Shiraz University of Medical Sciences, Shiraz, Iran. 2015 09 28 This study was aimed to evaluate the situation of congenital hypothyroidism (CH) in Guilan using the screening program and determine the correlation of CH with birth weight, gestational age and seasonality. During 2006 to 2010, in Guilan province, neonatal screening for CH by measurement of serum TSH level was performed in 3-5 days after birth. All neonates with TSH level ≥ 5mu/l were referred to endocrinologists and serum TSH, T3 and T4 were measured. Based on public health data and profiles, total number of newborns, gestational age, route of delivery, birth season and birth weight in all screened neonates was reviewed and for ones with CH, their TSH measurements was also recorded. 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 and birth season among patients with CH and the rest of the population. Interestingly, low birth weight (LBW) (31% vs. 4.9%, P<0.01), postdate delivery (1.4% vs. 0.2%, P<0.01) and macrosomia were more prevalent in CH versus normal population (Odds ratio for post-date delivery was 6.9 and for LBW was 3.2). Rate of normal vaginal delivery (NVD) was significantly higher in neonates with CH compared to normal population (39.2% vs. 29.2%, P=0.01). LBW, postdate delivery and macrosomia are risk factors for CH. No association between sex, birth season or caesarian section delivery was seen. https://acta.tums.ac.ir/index.php/acta/article/view/3985 https://acta.tums.ac.ir/index.php/acta/article/download/3985/3960