PERINATAL LUNG-FUNCTION AND INVASIVE ANTENATAL PROCEDURES

Background - Second trimester amniocentesis has been associated with a n excess of perinatal lung function abnormalities. Early amniocentesis might have a similar adverse effect, as could other invasive investig ations carried out in the first trimester. Methods - Plethysmographic measurements of thoracic gas volume (TGV) and airway resistance (Raw), from which specific conductance (sGaw) was calculated, were made in t he perinatal period in non-sedated infants. In addition, functional re sidual capacity (FRC) was measured using a helium gas dilution techniq ue. Measurements were made in 47 infants whose mothers had undergone e arly amniocentesis, 19 whose mothers had undergone chorion villus samp ling, and 25 controls whose mothers had undergone no invasive antenata l procedures. Results - The infants of mothers who had undergone early amniocentesis had higher TGV (95% CI -6.3 to 1.1 ml/kg) and Raw value s (95% CI - 10.68 to - 5.23 cm H2O/1/s) and lower sGaw (0.11 to 0.84 1 /cm H2O.s) and FRC (-5.17 to -0.87ml/kg) values than the controls. Inf ants whose mothers had undergone chorion villus sampling also differed significantly from the controls with higher Raw (- 7.59 to -1.99 cm H 2O/1/s) and lower sGaw values (0.11 to 0.241/cm H2O.s), and had lower Raw values than those in the early amniocentesis group (not significan t). Logistic regression analysis, taking into account possible risk fa ctors for abnormal lung function, showed that the procedures performed in the first trimester were independently associated with a high airw ays resistance. Conclusion - These results suggest that invasive proce dures performed in the first trimester of pregnancy have an adverse ef fect on perinatal lung function.