METHOD
uterine cervix ≤
PRETERM BIRTH, SECONDARY, PRETERM BIRTH, PRETERM DELIVERY
This is a cost-benefit ratio economic analysis, in which we compare the two scenarios of economic consequences: the implementation of a universal screening program for preterm birth This study is a secondary analysis of the P5 Study on Pessary and Progesterone in Preterm Birth Prevention To estimate the number of women who would be identified and treated, we targeted pregnant women with a singleton pregnancy. Those with a uterine cervix ≤ 25 mm, identified through TVUS during the second trimester (18–22 weeks, the recommended interval for the test), are at an increased risk of preterm delivery before 34 weeks. Consequently, they should receive 200 mg/day of vaginal progesterone as a preventive treatment for preterm birth. Based on a recent meta-analysis on the subject, we consider as a reference that the number needed for treatment in this group is 18, that is, for every 18 pregnant women with a cervix ≤ 25 mm who receive progesterone among those identified with a cervix ≤ 25 mm up to 36 weeks of gestation, one SPB < 34 weeks is avoided The P5 database contains the screening records of 7,892 women with singleton pregnancies, with 48 of whom lacked information regarding cervical measurement. Among the 7,844 women with complete screening data, the incidence of cervix ≤ 25 mm was 6.67%, a total of 523 patients. Following the literature information that for every 18 patients treated with vaginal progesterone we could reduce one SPB < 34 weeks, we can assume that universal screening followed by progesterone prophylaxis could reduce in our sample a total of 29 preterm deliveries < 34 weeks. To estimate the costs associated with treatment, we assumed in this model that treatment with vaginal progesterone 200 mg/day will be accepted and followed optimally by the patients identified from the 20th week to the 36th week of pregnancy.Due to the limitation of data in the literature that could help us identify the average cost of a SPB < 34 weeks in Brazil, we used our P5 trial database to calculate how much a preterm birth would cost based on the average value found in our sample of preterms births with < 34 weeks among the women with a cervix ≤ 25 mm. In constructing this value, we considered the costs of inputs and procedures from birth to the first 10 weeks after the probable date of delivery, including possible neonatal readmissions, according to the follow-up period of the research subjects defined by the P5 trial protocol to identify persistent neonatal pathological conditions ( 
