Background: There is growing evidence that advanced paternal age can be a reproductive hazard.
Methods: We studied couples and their first children using nationwide registers in Denmark between 1980 and 1996. We restricted the analysis to mother's age 20–29 years. We estimated odds ratios (ORs) of preterm (<37 weeks gestation) and very preterm birth (<32 weeks) as a function of paternal age using logistic regression to adjust for potential confounding variables.
Results: The risk of preterm birth increased with paternal age, almost entirely resulting from an association for very preterm birth. Compared with fathers age 20–24 years, ORs for very preterm birth were 1.3 (age 25–29), 1.4 (age 35–39), 1.7 (age 40–44), 1.6 (age 45–49), and 2.1 (age 50+) (test for trend: P = 0.01).
Conclusions: Risk of very preterm birth increases among older fathers, perhaps as a result of a paternal placental effect.
From the *Danish Epidemiology Science Centre and the †Department of Epidemiology and Social Medicine, University of Aarhus, Aarhus, Denmark.
Submitted 21 May 2004; final version accepted 18 June 2004.
This study was supported by a grant from the Danish Medical Research Council (grant no. 22-02-0363). The activities of the Danish Epidemiology Science Centre are financed by grants from the Danish National Research Foundation. Jin Liang Zhu is partly supported by the Daloon Foundation.
Correspondence: Jørn Olsen, The Danish Epidemiology Science Centre, University of Aarhus, Vennelyst Boulevard 6, DK-8000 Aarhus C, Denmark. E-mail: email@example.com.