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BJOG. 2016 Nov;123(12):2009-2017. doi: 10.1111/1471-0528.14165. Epub 2016 Jul 13.

Interpregnancy interval after live birth or pregnancy termination and estimated risk of preterm birth: a retrospective cohort study.

Author information

1
Division of Neonatal and Developmental Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA. bettyshachar@gmail.com, bshachar@stanford.edu.
2
Division of Neonatal and Developmental Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
3
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA, USA.
4
Department of Pediatrics, University of California San Diego, La Jolla, CA, USA.
5
Department of Epidemiology and Biostatistics, University of California, San Francisco, School of Medicine, San Francisco, CA, USA.

Abstract

OBJECTIVES:

We assessed whether interpregnancy interval (IPI) length after live birth and after pregnancy termination was associated with preterm birth (PTB).

DESIGN:

Multiyear birth cohort.

SETTINGS:

Fetal death, birth and infant death certificates in California merged with Office of Statewide Health Planning and Development.

POPULATION:

One million California live births (2007-10) after live birth and after pregnancy termination.

METHODS:

Logistic regression was used to estimate odds ratios (ORs) of PTB of 20-36 weeks of gestation and its subcategories for IPIs after a live birth and after a pregnancy termination. We used conditional logistic regression (two IPIs/mother) to investigate associations within mothers.

MAIN OUTCOME MEASURE:

PTB relative to gestations of ≥ 37 weeks.

RESULTS:

Analyses included 971 211 women with IPI after live birth, and 138 405 women with IPI after pregnancy termination with 30.6% and 74.6% having intervals of <18 months, respectively. IPIs of <6 months or 6-11 months after live birth showed increased odds of PTB adjusted ORs for PTB of 1.71 (95% CI 1.65-1.78) and 1.20 (95% CI 1.16-1.24), respectively compared with intervals of 18-23 months. An IPI >36 months (versus 18-23 months) was associated with increased odds for PTB. Short IPI after pregnancy termination showed a decreased OR of 0.87 (95% CI 0.81-0.94). The within-mother analysis showed the association of increased odds of PTB for short IPI, but not for long IPI.

CONCLUSIONS:

Women with IPI <1 or >3 years after a live birth were at increased odds of PTB-an important group for intervention to reduce PTB. Short IPI after pregnancy termination was associated with reduced odds for PTB and needs to be further explored.

TWEETABLE ABSTRACT:

Short and long IPI after live birth, but not after pregnancy termination, showed increased odds for PTB.

KEYWORDS:

Interpregnancy interval; preterm birth; prevention; risk assessment

PMID:
27405702
DOI:
10.1111/1471-0528.14165
[Indexed for MEDLINE]
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