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Am J Perinatol 2023; 40(09): 917-922
DOI: 10.1055/a-2008-2495
SMFM Fellowship Series Article

Understanding Preterm Birth in Pregnancies Complicated by Nonimmune Hydrops Fetalis

Kate Swanson 
1   Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California
2   Division of Medical Genetics, Department of Pediatrics, University of California, San Francisco, California
,
Mary E. Norton
1   Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California
2   Division of Medical Genetics, Department of Pediatrics, University of California, San Francisco, California
3   Fetal Treatment Center, University of California, San Francisco, California
4   Institute for Human Genetics, University of California, San Francisco, California
,
Sarah L. Downum
1   Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California
,
Juan M. Gonzalez-Velez
1   Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California
3   Fetal Treatment Center, University of California, San Francisco, California
,
Teresa N. Sparks
1   Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California
3   Fetal Treatment Center, University of California, San Francisco, California
4   Institute for Human Genetics, University of California, San Francisco, California
› Author Affiliations
Funding Supported by the University of California, San Francisco (UCSF) Center for Maternal–Fetal Precision Medicine, the Brianna Marie Foundation in collaboration with the Fetal Health Foundation, and grants (5K12HD001262-18 and R01HD107190, supporting Dr. Sparks, and U01HG009599, to Dr. Norton) from the National Institutes of Health (NIH). The contents of the publication are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. The funding sources had no role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.
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Abstract

Objective Nonimmune hydrops fetalis (NIHF) is associated with poor perinatal outcomes including preterm birth (PTB). However, the frequency and causes of PTB in this population are not well understood. We hypothesized that NIHF frequently results in PTB due to medically indicated delivery for fetal distress.

Study Design This was a secondary analysis of a prospectively enrolled cohort of pregnancies with NIHF that underwent exome sequencing if standard testing was nondiagnostic. The primary outcome was frequency of PTB at <37 weeks' gestation. Secondary outcomes were reasons for PTB, fetal predictors of PTB, and frequency of neonatal death following PTB.

Results Fifty-six cases were included, with a median gestational age at delivery of 32.8 weeks (interquartile range [IQR]: 30.3–35.0). Overall, 86% (48/56) were delivered preterm. Among 48 PTBs, 18 (38%) were spontaneous, 9 (19%) were medically indicated for maternal indications (primarily preeclampsia), and 21 (44%) were medically indicated for fetal indications (nonreassuring antenatal testing or worsening effusions). Neither fetal genetic diagnosis nor polyhydramnios was associated with PTB.

Conclusion More than four-fifths of pregnancies with NIHF result in PTB, often due to nonreassuring fetal status. These data are informative for counseling patients and for developing strategies to reduce PTB in pregnancies with NIHF.

Key Points

  • Pregnancies complicated by nonimmune hydrops fetalis often result in preterm birth.

  • Preterm birth in these cases is most often medically indicated for fetal benefit.

  • Fetal genetic conditions and polyhydramnios may be associated with preterm birth in cases of NIHF.

Keywords

preterm birth - nonimmune hydrops fetalis - hydrops - fetal fluid - collections - fetal effusions


Publication History

Received: 30 August 2022

Accepted: 05 January 2023

Accepted Manuscript online:
05 January 2023

Article published online:
16 February 2023

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