Analysis on the analysis people was get across-tabulated of the infant intercourse, GA, in addition to two-time episodes (1973–1978 and you can 1995–2010)
As a first step, rates of adverse outcomes per 1000 live births were calculated according to infant sex, GA, and the studied period. Thereafter, for each time period, using the gestational age categories as the exposure variable (early term and late preterm infants, respectively, with midterm infants as the reference category), we used logistic regression to estimate odds for prematurity-related adverse outcomes such as neonatal death, low Apgar score (<7 at 5 min), pneumothorax, RDS, other respiratory conditions, and hyperbilirubinemia. Then, for each time period, odds ratios (ORs) with 95 % confidence intervals (CIs) for adverse prematurity-related outcomes among male infants, always in relation to their female counterparts, were calculated with logistic regression, separately for early term and for late preterm infants. Finally, to estimate the change in male risk before and after the introduction of ultrasound pregnancy dating, the relative change in odds for adverse prematurity-related outcomes between the two periods, among male infants in the early term and late preterm groups in relation to their female counterparts, was calculated as the ratio between the ORs for each period (Cohort Ratio, CR). The multivariate analyses were adjusted for maternal age, parity, and level of hospital care.
The latest analytical analyses was used using the SAS 9.step 3 software package (SAS Institute, Cary, NC, USA). The fresh new ORs and you may CRs through its 95 % count on menstruation have been projected on the GENMOD process.
Overall performance
The advantages of your own study cohorts are demonstrated when you look at the Table step one , on the level of men and women infants produced within the for each and every GA classification while in the 1973–1978 and you will 1995–2010. Brand new ratio out-of midterm births (74.6 % in the early compared to. 70.5 % regarding the late several months) are higher during the early cohort, in addition to proportion away from very early term births (21.0 % during the early vs. 25.5 % about late several months) is lower in early cohort. (далее…)