Aaron B. Caughey


 Perinatal outcomes differ by week of gestational age. However, it appears that  how measures to examine these outcomes vary among various studies. The current  paper explores how perinatal complications are reported and how they might  differ when different denominators, numerators, and comparison groups are  utilized.
 
 


 One issue that can clearly affect absolute rates and trends is how groups of  women are categorized by their gestational age. Since most perinatal outcomes  can only occur in women and neonates who have delivered, using the number of  pregnancies delivered (PD) as the denominator of outcomes is appropriate.  However, for an outcome such as antepartum stillbirth, all women who are  pregnant at a particular gestational age are at risk. Thus, the denominator  should include all ongoing pregnancies (OP). When gestational age is used by  week this means using both deliveries during a particular week plus those women  who deliver beyond the particular week of gestation in the denominator.  Researchers should be careful to make sure they are utilizing the appropriate  measure of perinatal complications so they do not report findings that would be  misleading to clinicians, patients, and policy makers. 

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BMC Pregnancy and Childbirth 2007, 7:18doi:10.1186/1471-2393-7-18

Articles

Perinatal outcomes differ by week of gestational age. However, it appears that how measures to examine these outcomes vary among various studies. The current paper explores how perinatal complications are reported and how they might differ when different denominators, numerators, and comparison groups are utilized.

Aaron B. Caughey

Articles

Measuring Perinatal Complications: Methodologic Issues Related to Gestational Age