LAUSR

BACKGROUND Maternal and paternal age at first birth is increasing across the global population. Spontaneous abortion, one of the most common abnormal pregnancy outcomes, is known to occur more frequently with increasing maternal age. However, the relationship of advanced paternal age and spontaneous abortion is poorly understood and previous results have yielded conflicting results. OBJECTIVE To examine the influence of paternal age on the risk of spontaneous abortion (SAB) among singleton pregnancies conceived without assisted reproductive technologies. STUDY DESIGN Retrospective, case-control study using combined pregnancy data from the CDC's 2011-2013 and 2013-2015 National Survey of Family Growth. Spontaneous, singleton pregnancy data from women, ages 15-45 years, were analyzed. Ongoing pregnancies, induced abortions, ectopic pregnancies, preterm births, and intrauterine fetal deaths were excluded. Bivariate associations of pregnancy outcome (SAB at <20 weeks and <12 weeks versus live birth at >37 weeks) and paternal age were determined, along with those of maternal age and select demographic and pregnancy characteristics. Significant associations were included in a multivariable logistic regression, which accounted for multiple pregnancies derived from the same respondent. RESULTS A total of 12,710 pregnancies from 6,979 women were analyzed, consisting of 2,300 (18.2%) SABs and 10,410 (81.8%) term live births. Median maternal and paternal ages were 25 and 28, respectively. After adjusting for maternal age, race/ethnicity, socioeconomic status, marital status, and pregnancy intention, pregnancies resulting in SAB had 2.05 (95%CI 1.06-2.20) times the odds of being from a father aged 50 years or older, versus 25-29 years of age. These relationships remained significant when defining SABs at < 12 weeks (adjOR: 2.30, 95%CI 1.17-4.52). CONCLUSIONS Paternal age may increase the odds of SAB, independent of select factors, including demographics, pregnancy intention, and maternal age. This association was robust across several gestational age-based definitions of SAB, even after adjustment.