title: Relationship between maternal thyroid-stimulating hormone (TSH) elevation during pregnancy and low birth weight: a longitudinal study of apparently healthy urban Japanese women at very low risk.
abstract: OBJECTIVE
  Thyroid hormones cross the placenta and promote fetal development and growth. The present study investigated whether an increase in maternal thyroid-stimulating hormone (TSH) concentration between the first and third trimesters is a determinant of birth weight during normal pregnancy.
  
  
  METHODS
  Maternal thyroid hormones and TSH were longitudinally measured at 12, 25, and 36weeks of pregnancy in 163 healthy pregnant women. Low birth weight (LBW) was defined as less than 2500g. ∆TSH12-36W was calculated as the difference in TSH concentrations between 12 and 36weeks of pregnancy.
  
  
  RESULTS
  Of the 163 neonates, 10 (6.1%) were LBW neonates. Free triiodothyronine and free thyroxine levels were similar at all gestational ages in the normal birth weight (Normal) and LBW groups. However, the median ∆TSH12-36W value was higher in the LBW than the Normal group (1.67 vs. 0.54mIU/L, P=0.008). Multivariate linear regression analysis showed that ∆TSH12-36 was inversely correlated with birth weight (β=-0.179, P=0.008).
  
  
  CONCLUSIONS
  An increase in maternal TSH concentration between the first and third trimesters is an independent determinant of birth weight in normal pregnancy.
authors: Department of Epidemiology and Environmental Health, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan; Department of Midwifery and Women's Health, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Kobe, Hyogo 654-0142, Japan.
authors: Emiko
authors: E
authors: Nishioka
authors: Department of Clinical Laboratory Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. Electronic address: sthiraya@juntendo.ac.jp.
authors: Satoshi
authors: S
authors: Hirayama
authors: Department of Clinical Laboratory Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors: Tsuyoshi
authors: T
authors: Ueno
authors: Department of Epidemiology and Environmental Health, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors: Takehisa
authors: T
authors: Matsukawa
authors: Department of Epidemiology and Environmental Health, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan; National Institute of Occupational Safety and Health, Nagao 6-21-1 Tama-ku, Kawasaki-city, Kanagawa, 204-0024, Japan.
authors: Mohsen
authors: M
authors: Vigeh
authors: Department of Epidemiology and Environmental Health, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors: Kazuhito
authors: K
authors: Yokoyama
authors: Department of Obstetrics and Gynecology, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors: Shintaro
authors: S
authors: Makino
authors: Department of Obstetrics and Gynecology, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors: Satoru
authors: S
authors: Takeda
authors: Department of Clinical Laboratory Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors: Takashi
authors: T
authors: Miida
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007564:Japan; D008137:Longitudinal Studies; D008297:Male; D011247:Pregnancy / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*
chemical_list: D013972:Thyrotropin
keywords: Birth weight; Fetal growth; Normal pregnant women; Subclinical hypothyroidism; Thyroid-stimulating hormone