title: The association between maternal nonylphenol exposure and parity on neonatal birth weight: a cohort study in Taiwan.
abstract: BACKGROUND
  The aim of this study was to explore the association between NP exposure and parity and their effect on neonatal birth weight.
  
  
  METHODS
  A cohort of pregnant women was established in a medical center in North Taiwan. Urinary NP concentration was determined by high-performance liquid chromatography coupled with fluorescent detection and adjusted using creatinine. A multivariable regression model was fit to determine the association between the maternal NP level in each trimester and neonatal birth weight. The odds ratios (ORs) of infant birth weight below the 10th, 25th, and 50th percentiles, comparing pregnant women with the different NP exposure levels, was estimated using a logistic regression.
  
  
  RESULTS
  Of the 162 pregnant women in the study, 99 were multiparas and 63 were primiparas. After adjusting for other covariates, the NP level in the second trimester had a significant association with birth weight in the primiparas (β = -182.49 g, p value = 0.02). The OR of low infant birth weight, comparing pregnant women with different NP levels, was increased by decreasing the cutoff percentile for birth weight (OR = 1.18 for the 50th percentile, 2.12 for the 25th percentile, and 7.81 for the 10th percentile). The odds of primiparas with high NP level having a low neonatal birth weight increased to 3.87, 11.77, and 9.40 for the three different percentiles (p value < 0.05).
  
  
  CONCLUSIONS
  Maternal NP exposure level is associated with an increased risk of low neonatal weight. Primiparas are especially at risk, and the second trimester of pregnancy may be the critical stage of exposure.
authors.affiliation: Institute of Environmental and Occupational Health Sciences, National Yang Ming University, Taipei, Taiwan.
authors.forename: Chia-Huang
authors.initials: CH
authors.lastname: Chang
authors.forename: Mei-Lien
authors.initials: ML
authors.lastname: Chen
authors.forename: Kai-Wei
authors.initials: KW
authors.lastname: Liao
authors.forename: Yen-An
authors.initials: YA
authors.lastname: Tsai
authors.forename: I-Fang
authors.initials: IF
authors.lastname: Mao
authors.forename: Tzu-Hao
authors.initials: TH
authors.lastname: Wang
authors.forename: Shiaw-Min
authors.initials: SM
authors.lastname: Hwang
authors.forename: Yu-Jen
authors.initials: YJ
authors.lastname: Chang
authors.forename: Ming-Song
authors.initials: MS
authors.lastname: Tsai
mesh_terms: D000328:Adult; D001724:Birth Weight; D015331:Cohort Studies; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D006801:Humans; D007223:Infant; D016015:Logistic Models; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D016017:Odds Ratio; D010298:Parity; D010636:Phenols / Q000097:blood*; D011247:Pregnancy; D013624:Taiwan
chemical_list: D004785:Environmental Pollutants; D010636:Phenols; C025256:nonylphenol
keywords: Birth weight; Nonylphenol; Pregnant woman; Primipara