title: Temperature during pregnancy influences the fetal growth and birth size.
abstract: BACKGROUND
  Birth weight and length have seasonal fluctuations. However, it is uncertain which meteorological element has an effect on birth outcomes and which timing of pregnancy would explain such effect. Therefore, the purpose of this study was to examine temperature effects during pregnancy and which timing of pregnancy has effects on size at birth.
  
  
  METHODS
  A large, randomized, controlled trial of food and micronutrient supplementation for pregnant women was conducted in Matlab, Bangladesh (MINIMat Study), where women were enrolled from November 2001 to October 2003. The fetal growth data which included the size at birth and information of their mothers were obtained (n= 3267). Meteorological data such as temperature, precipitation, relative humidity, and daily sunshine hours during pregnancy were observed at the nearest observatory site of Bangladesh Meteorological Department.
  
  
  RESULTS
  Infants born in colder months (November-January) were shorter than those born in hot and dry, and monsoon months (mean (SD) of birth length was 47.5 cm (2.2) vs. 47.8 cm (2.1) vs. 47.9 cm (2.1) respectively;P< 0.001). Increased temperature during the last month of pregnancy was significantly related with increased birth length with adjustment for gestational weeks and the season at birth, and remained significant with further adjustments for precipitation, sex of infants, maternal early-pregnancy BMI, parity, and education status of the mother (P< 0.01). On the other hand, increased temperature at mid-gestation was associated with increased birth weight (P< 0.05).
  
  
  CONCLUSIONS
  These findings suggest that temperature affects both birth weight and length. The more temperature increased at the last month of pregnancy, birth length became longer. For birth weight, the temperature at mid-pregnancy affected in a positive way.
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan ; International Centre for Diarrhoeal Diseases Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Harunor
authors.initials: H
authors.lastname: Rashid
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Kagami
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
authors.forename: Farzana
authors.initials: F
authors.lastname: Ferdous
authors.affiliation: Department of Clinical Trial and Clinical Epidemiology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 Japan.
authors.forename: Enbo
authors.initials: E
authors.lastname: Ma
authors.affiliation: Faculty of Education, Kagawa University, Takamatsu, Kagawa Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Terao
authors.affiliation: Center for Southeast Asian Studies, Kyoto University, Kyoto, Japan.
authors.forename: Taiichi
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Department of Clinical Trial and Clinical Epidemiology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 Japan.
authors.forename: Yukiko
authors.identifier: 0000-0002-8056-9998
authors.initials: Y
authors.lastname: Wagatsuma
keywords: Birth length; Birth weight; Temperature