Respiratory function in singleton and twin pregnancy.
OBJECTIVE
Singleton pregnancy causes important changes in respiratory function. The incidence of twin pregnancies is increasing, but it is not known whether affected women suffer greater respiratory compromise. The aim of this study was to determine if changes in respiratory function during pregnancy in healthy women were greater in those with a twin pregnancy compared with those with a singleton pregnancy.


METHODS
Cross sectional study.


METHODS
London teaching hospital.


METHODS
Healthy pregnant women attending the antenatal clinic and ultrasound department.


METHODS
A cross sectional study of respiratory function was performed in 68 women with twin pregnancies (17 examined in the first trimester, 35 second trimester, 16 third trimester) and 140 women with singleton pregnancies (28, 80, 40, respectively) and 22 non-pregnant women. Women were examined once between 7 and 40 weeks of gestation. Forced vital capacity, relaxed vital capacity, forced expiratory volume in 1 second (FEV1), peak flow, inspiratory capacity, functional residual capacity (FRC), expiratory reserve volume, pulmonary diffusing capacity and minute ventilation were measured.


RESULTS
Both in twin and singleton pregnancies, the mean FRC and expiratory reserve ventilation of women studied in the third trimester and minute ventilation of women studied in each trimester differed significantly from that of the non-pregnant women. There were, however, no significant differences demonstrated in respiratory function between healthy women with twin as compared with singleton pregnancies.


CONCLUSIONS
In healthy women, the extra demands of atwin compared with a singleton pregnancy do not compromise further the respiratory system.
Harris Birthright Research Centre for Fetal Medicine, King's College, London, UK.
Fionnuala
F
McAuliffe
Nikos
N
Kametas
John
J
Costello
Gerrard F
GF
Rafferty
Anne
A
Greenough
Kypros
K
Nicolaides
D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D005652:Functional Residual Capacity / Q000502:physiology; D006801:Humans; D010366:Peak Expiratory Flow Rate / Q000502:physiology; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000502:physiology*; D012119:Respiration; D014427:Twins; D014797:Vital Capacity / Q000502:physiology