title: Pulmonary function in advanced uncomplicated singleton and twin pregnancy.
abstract: OBJECTIVE
  Pregnancy brings about significant changes in respiratory function, as evidenced by alterations in lung volumes and capacities, which are attributable to the mechanical impediment caused by the growing foetus. This study was undertaken in order to identify changes in respiratory function during normal pregnancy and to determine whether such changes are more pronounced in twin pregnancy than in singleton pregnancy.
  
  
  METHODS
  Respiratory function was assessed in 50 women with twin pregnancies and in 50 women with singleton pregnancies (during the third trimester in both groups), as well as in 50 non-pregnant women. We measured the following pulmonary function test parameters: FVC; FEV1; PEF rate; FEV1/FVC ratio; FEF25-75%; and maximal voluntary ventilation.
  
  
  RESULTS
  All respiratory parameters except the FEV1/FVC ratio were found to be lower in the pregnant women than in the non-pregnant women. We found no significant differences between women with twin pregnancies and those with singleton pregnancies, in terms of respiratory function.
  
  
  CONCLUSIONS
  Despite its higher physiological demands, twin pregnancy does not appear to impair respiratory function to any greater degree than does singleton pregnancy.
authors.affiliation: Department of Physiology, Jawaharlal Nehru Medical College, Aligarh, India.
authors.forename: Anwar Hasan
authors.initials: AH
authors.lastname: Siddiqui
authors.affiliation: Department of Anaesthesiology and Critical Care, Jawaharlal Nehru Medical College, Aligarh, India.
authors.forename: Nazia
authors.initials: N
authors.lastname: Tauheed
authors.affiliation: Department of Physiology, Jawaharlal Nehru Medical College, Aligarh, India.
authors.forename: Aquil
authors.initials: A
authors.lastname: Ahmad
authors.affiliation: Department of Obstetrics and Gynaecology, Jawaharlal Nehru Medical College, Aligarh, India.
authors.forename: Zehra
authors.initials: Z
authors.lastname: Mohsin
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008168:Lung / Q000502:physiology*; D011247:Pregnancy / Q000502:physiology*; D011263:Pregnancy Trimester, Third / Q000502:physiology*; D059285:Pregnancy, Twin / Q000502:physiology*; D012119:Respiration; D012129:Respiratory Function Tests; D055815:Young Adult