1.2. Determination of stillbirth risk among relatives
We used logistic regression models to estimate the odds ratio (95%
confidence interval [95%: CI]) of stillbirth, comparing the odds of
stillbirth in relatives of parents of stillbirth cases to the odds of
stillbirth in relatives of parents of live birth controls. Estimates
were adjusted for birth year, race (whether non-Hispanic White), and
ethnicity (whether Hispanic). Case-control statuses of FDRs, SDRs and
TDRs of affected and unaffected parents were similarly ascertained using
identical case and control definitions in probands. To identify distinct
parent-of-origin effects on stillbirth, we conducted parental
sex-specific analyses. Statistical
analyses were carried out using SAS (version 9.4, SAS Institute Inc.,
Cary, NC), R (version 4.0.2), and STATA version 15.0 (StataCorp, College
Station, TX).