title: Urine color as an indicator of urine concentration in pregnant and lactating women.
abstract: OBJECTIVE
  Urine concentration measured via osmolality (UOSM) and specific gravity (USG) reflects the adequacy of daily fluid intake, which has important relationships to health in pregnant (PREG) and lactating (LACT) women. Urine color (UCOL) may be a practical, surrogate marker for whole-body hydration status.
  
  
  OBJECTIVE
  To determine whether UCOLwas a valid measure of urine concentration in PREG and LACT, and pair-matched non-pregnant, non-lactating control women (CON).
  
  
  METHODS
  Eighteen PREG/LACT (age 31 ± 1 years, pre-pregnancy BMI 24.3 ± 5.9 kg m-2) and eighteen CON (age 29 ± 4 years, BMI 24.1 ± 3.7 kg m-2) collected 24-h and single-urine samples on specified daily voids at five time points (15 ± 2, 26 ± 1, and 37 ± 1 weeks gestation, 3 ± 1 and 9 ± 1 weeks postpartum during lactation; CON visits were separated by similar time intervals) for measurement of 24-h UOSM, USG, and UCOLand single-sample UOSMand UCOL.
  
  
  RESULTS
  Twenty-four-hour UCOLwas significantly correlated with 24-h UOSM(r = 0.6085-0.8390, P < 0.0001) and 24-h USG(r = 0.6213-0.8985, P < 0.0001) in all groups. A 24-h UCOL≥ 4 (AUC = 0.6848-0.9513, P < 0.05) and single-sample UCOL≥ 4 (AUC = 0.9094-0.9216, P < 0.0001) indicated 24-h UOSM≥ 500 mOsm kg-1(representing inadequate fluid intake) in PREG, LACT, and CON.
  
  
  CONCLUSIONS
  Urine color was a valid marker of urine concentration in all groups. Thus, PREG, LACT, and CON can utilize UCOLto monitor their daily fluid balance. Women who present with a UCOL≥ 4 likely have a UOSM≥ 500 mOsm kg-1and should increase fluid consumption to improve overall hydration status.
authors.affiliation: Human Performance Laboratory, Department of Kinesiology, University of Connecticut, 2095 Hillside Road, U1110, Storrs, CT, 06269-1110, USA. amylmckenzie@gmail.com.
authors.forename: Amy L
authors.identifier: http://orcid.org/0000-0003-4549-5177
authors.initials: AL
authors.lastname: McKenzie
authors.affiliation: Department of Health Sciences and Nursing, University of Hartford, 200 Bloomfield Ave, West Hartford, CT, 06117, USA.
authors.forename: Colleen X
authors.initials: CX
authors.lastname: Muñoz
authors.affiliation: Centre for Heart Lung and Vascular Health, University of British Columbia, 1147 Research Road, Kelowna, BC, V1V 1V7, Canada.
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Ellis
authors.affiliation: Danone Research, RD 128, 91767, Palaiseau, France.
authors.forename: Erica T
authors.initials: ET
authors.lastname: Perrier
authors.affiliation: Danone Research, RD 128, 91767, Palaiseau, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Guelinckx
authors.affiliation: Danone Research, RD 128, 91767, Palaiseau, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Klein
authors.affiliation: Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, 155 Stadium Drive, HPER 321, Fayetteville, AR, 72701, USA.
authors.forename: Stavros A
authors.initials: SA
authors.lastname: Kavouras
authors.affiliation: Human Performance Laboratory, Department of Kinesiology, University of Connecticut, 2095 Hillside Road, U1110, Storrs, CT, 06269-1110, USA.
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Armstrong
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine; D015992:Body Mass Index; D016022:Case-Control Studies; D003116:Color; D003681:Dehydration / Q000175:diagnosis* / Q000652:urine*; D004326:Drinking; D005260:Female; D006801:Humans; D007774:Lactation; D009994:Osmolar Concentration; D011247:Pregnancy; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013046:Specific Gravity; D016482:Urinalysis; D014882:Water-Electrolyte Balance
chemical_list: D015415:Biomarkers
keywords: Biomarker; Fluid intake; Hydration status; Lactating women; Pregnant women; Urine color