Impact of advanced maternal age on neonatal survival of twin small-for-gestational-age subtypes

Aim: We examined the impact of advanced maternal age (>40 years old) on the survival of twin small‐for‐gestational‐age (SGA) infants, that is, infants who were smaller in size than was expected for the baby's sex, genetic heritage, and gestational age. Methods: The present study was a retrospective cohort study on twin live births in the USA from 1995 to 1998 inclusive. Two categories of SGA babies were defined: discordant (when only one of a twin pair was SGA) and concordant (when both were SGA). Otherwise, the twin pair was appropriate‐for‐gestational‐age (AGA) concordant. Results: 192 195 twin pairs were analyzed. The incidence of SGA discordance and concordance was 11.8% and 3.9%, respectively. The occurrence of both SGA subtypes tended to decrease with increasing maternal age. The unadjusted risk for neonatal mortality increased when both twins were affected (15.8: 22.8 and 56.6 per 1000 among AGA concordant, SGA discordant and SGA concordant twins; P‐value for trend