Changes in the size of the lateral ventricles in the normal-term newborn following vaginal delivery.

Background: This is a study of the size of the lateral ventricles in a population of normal-term newborns following vaginal delivery.

Objective: To assess the time course for the lateral ventricles to change from closed to open following vaginal delivery.

Materials And Methods: A total of 143 normal-term newborns had a videotaped cranial ultrasound examination during the period from 1 to 156 h after birth. Many had from one to three additional examinations when returning for well-baby checks. Three methods [overlapping intervals (smoothed percentages), life table, and geometric distribution] were used to construct the approximate distributions of completely closed, partially open, and open ventricles.

Results: Using smoothed percentages it was estimated that within 12 h of birth, 80% of newborns had closed lateral ventricles, 19% had partially open ventricles, and only 1% were completely open. The estimated median time from birth to partially open ventricles was in the period 36 to 60 h. The life table gave the estimated median time to partially open ventricles as 74 h. Fitting the data to a geometric distribution gave an estimated mean of 63 h.

Conclusion: The majority of normal newborns have closed lateral ventricles following vaginal delivery and these are partially opened by day 3 after birth.