title: Effect of external airflow resistive load on postural and exercise-associated cardiovascular and pulmonary responses in pregnancy: a case control study.
abstract: BACKGROUND
  Facial coverings (e.g., balaclavas, niqabs, medical/surgical masks, respirators, etc.), that impose low levels of airflow resistive loads, are worn by millions of pregnant women worldwide, but little data exist addressing their impact on pregnancy-associated cardiovascular and pulmonary responses.
  
  
  METHODS
  16 pregnant and 16 non-pregnant women were monitored physiologically (heart rate, blood pressure, mean arterial pressure, total peripheral resistance, stroke volume, cardiac output, oxygen saturation, transcutaneous carbon dioxide, fetal heart rate) and subjectively (exertion) for 1 h of mixed sedentary postural activity (sitting, standing) and moderate exercise (bicycle ergometer) with and without wearing N95 filtering facepiece respirators with filter resistive loads of 94.1 Pa (9.6 mm H2O) - 119.6 Pa (12.2 mm H2O) pressure.
  
  
  RESULTS
  The external airflow resistive loads were associated with increases in diastolic pressure (p = 0.004), mean arterial pressure (p = 0.01), and subjective exertion score (p < 0.001) of all study subjects. No significant differences were noted with the external resistive loads between the pregnant and non-pregnant groups for any cardiovascular, pulmonary and subjective variable over 1 h.
  
  
  CONCLUSIONS
  Low external airflow resistive loads, during combined sedentary postural activity and moderate exercise over 1 h, were associated with increases in the diastolic and mean arterial pressures of all study subjects, but pregnancy itself was not associated with any significant differences in physiologic or subjective responses to the external airway resistive loads utilized in the study.
authors.affiliation: National Personal Protective Technology Laboratory, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 626 Cochrans Mill Road, Pittsburgh, 15236, PA, USA. inr3@cdc.gov.
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: National Personal Protective Technology Laboratory, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 626 Cochrans Mill Road, Pittsburgh, 15236, PA, USA. dtn0@cdc.gov.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Roberge
authors.affiliation: National Personal Protective Technology Laboratory, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 626 Cochrans Mill Road, Pittsburgh, 15236, PA, USA. efe8@cdc.gov.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Powell
mesh_terms: D000328:Adult; D000403:Airway Resistance; D001794:Blood Pressure / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D005080:Exercise Test / Q000379:methods; D005260:Female; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008991:Monitoring, Physiologic / Q000379:methods; D009064:Mouth Protectors / Q000009:adverse effects / Q000145:classification; D010101:Oxygen Consumption; D011247:Pregnancy; D015656:Respiratory Mechanics; D012143:Respiratory Physiological Phenomena