THIS INFANT was born at 40 weeks' gestation to a 29-year-old gravida 2, para 0 white woman by vacuum delivery. Birth weight was 3770 g; crown-heel length, 56 cm; head circumference, 35.5 cm. Apgar scores were 7 and 7 at 1 and 5 minutes, respectively. Initial resuscitation included oropharyngeal suctioning and oxygen supplementation by face mask. Respiratory difficulty was soon noted. Ambient oxygen concentration was increased without benefit. At 1½ hours of age, he underwent intubation and ventilation. A chest radiograph showed bilateral pneumothoraces (Figure 1) that were drained through indwelling chest tubes with immediate improvement in oxygen saturation from 72% to 100%. Complete blood cell count, serum electrolyte level, and blood glucose level were normal. Arterial blood gas measurement showed pH, 7.45; PaO2, 73 mm Hg; PaCO2, 24 mm Hg; and bicarbonate, 17 mmol/L. Ventilatory rate ranged between 22 and 40/min; peak inspiratory pressure between 26 and