Am J Perinatol 2017; 34(11): 1054-1057
DOI: 10.1055/s-0037-1603679
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Trisomy 18 Pregnancies: Is there an Increased Maternal Risk?

Sarah K. Dotters-Katz
1  Division of Maternal Fetal Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
Kayli L. Senz
2  Department of Obstetrics and Gynecology, Case Western Reserve University, Cleveland, Ohio
Whitney M. Humphrey
3  Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan
Vanessa R. Lee
4  Division of Maternal Fetal Medicine, Oregon Health and Science University, Portland, Oregon
Aaron B. Caughey
4  Division of Maternal Fetal Medicine, Oregon Health and Science University, Portland, Oregon
› Author Affiliations
Further Information

Publication History

28 April 2017

28 April 2017

Publication Date:
02 June 2017 (online)


Objective Characterize the impact of a trisomy 18 (T18) fetus on maternal and obstetric outcomes in a cohort including T18-affected deliveries.

Study Design Retrospective cohort study of singleton deliveries in California from 2005 to 2008 using linked vital statistics and the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9) data to compare deliveries affected by T18 to those without known aneuploidy. Outcomes of interest included gestational diabetes mellitus (GDM), preterm delivery (PTD), preeclampsia, cesarean delivery (CD), and intrauterine fetal demise (IUFD). The χ2 and paired t-tests were used to compare the outcomes. Multiple logistic regression was used to further characterize these risks and control potential confounders.

Results Of 2,029,000 deliveries, 298 involved T18. Compared with unaffected deliveries, T18 was associated with GDM (10.7 vs. 6.5%, p = 0.003), PTD < 37 (40.6 vs. 9.9%, p < 0.001) and < 32 weeks (14.8 vs. 1.4%, p < 0.001), and cesarean section (56 vs. 30.2%, p < 0.001), but not preeclampsia. In adjusted analyses, T18 pregnancies were associated with an increased risk of PTD < 37 and < 32 weeks (adjusted odds ratio [AOR]: 5.48, 95% confidence interval [CI]: 4.29, 6.99; AOR: 10.4, 95% CI: 7.26, 14.8), and an increased odd of CD for primiparous and multiparous women (AOR: 2.41, 95% CI: 1.48, 3.91; AOR: 5.42, 95% CI: 3.90, 7.53). Risk of GDM did not persist.

Conclusion Unlike trisomy 13 (T13), pregnancies complicated by fetal T18 did not appear to result in an increased risk of preeclampsia. However, there is an increased risk of a range of other obstetric complications.


Though not associated with an increased risk of preeclampsia, T18 pregnancies are 2.5 times more likely be delivered by cesarean, and 10 times more likely to deliver at less than 32 weeks.


This article was presented in part as a poster at the 37th Annual Society of Maternal Fetal Medicine Meeting in 2017, Las Vegas, Nevada.