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Impact of advanced maternal age on neonatal survival of twin small‐for‐gestational‐age subtypes
Author(s) -
Kristensen Sibylle,
Salihu Hamisu M.,
Keith Louis G.,
Kirby Russell S.,
Pass Mary A. B.,
Fowler Karen B.
Publication year - 2007
Publication title -
journal of obstetrics and gynaecology research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 1341-8076
DOI - 10.1111/j.1447-0756.2007.00521.x
Subject(s) - medicine , concordance , small for gestational age , gestational age , obstetrics , incidence (geometry) , appropriate for gestational age , pediatrics , retrospective cohort study , advanced maternal age , cohort , zygosity , pregnancy , fetus , physics , biology , optics , genetics
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 < 0.0001). Using maternal‐age‐specific AGA babies as reference, the adjusted risk for neonatal mortality climbed progressively with advancing maternal age in a dose‐dependent pattern, being lowest among teenagers and highest in mothers aged ≥40 years. Conclusions: SGA discordance and concordance declined with advancing maternal age. In contrast, neonatal mortality of both SGA subtypes worsened with the increase in maternal age compared with that of the age‐specific AGA infants. These findings are potentially useful to care providers in counseling older women, a group that is progressively increasing in size and is most susceptible to twining.