Normal Values For Fetal Thoracic Parameters

Abstract

Objective To determine nomograms for fetal thoracic measurements during the second and third trimesters. Design Prospective study

Subjects Normal pregnant women between 18 and 40 weeks of gestation, having their first antenatal visit during first trimester of pregnancy at King Chulalongkorn Memorial Hospital between December 1996 to October 1997 were recruited into this study. All pregnancies were singleton with known date of the beginning of the last normal menstrual period and confirmed by first trimester ultrasound. Patients with suspected anomalies, intrauterine growth restriction, fetal macrosomia, or severe oligohydramnios were excluded. The thoracic measurements obtained for each fetus were thoracic circumference and thoracic area. Thoracic circum ference measurements were made according to the method of Nimrod et al.

Results 134 normal pregnant women were evaluated. Nomograms for fetal thoracic circumference and thoracic area with respect to gestational age from 18 to 40 weeks were developed.

Conclusion Nomograms for thoracic circumference and thoracic area with respect to gestational age were developed for the Thai population. These data might be helpful to establish normal values for fetal thoracic growth, in order to evaluate abnormal lung development in prolonged premature rupture of membranes, and in asso ciation with certain fetal abnormalities.