Review Article
Temporal changes in rates of stillbirth, neonatal and infant mortality among triplet gestations in the United States

https://doi.org/10.1016/j.ajog.2006.01.043Get rights and content

Objective

The purpose of this study was to examine temporal changes in stillbirth, neonatal and infant mortality rates among triplet births in the US, and to assess the contributions of triplet delivery at <34 weeks to these changes.

Study design

Data on triplet live births, and fetal and infant deaths (1990-2002) delivered at ≥22 weeks and fetuses weighing ≥500 g (n = 66,986) were derived from the US linked birth/infant death data files. Relative risk (RR), quantifying changes in triplet stillbirth, neonatal (death within the first 28 days) and infant mortality (death within the first year) rates between 1990 and 1991 and 2001 and 2002, were derived. Temporal changes in triplet births at <34 weeks, and changes in stillbirth, and neonatal and infant mortality rates were examined through logistic regression models before and after adjusting for confounders.

Results

Triplet births at <34 weeks increased by 25% between 1990 and 1991 (48.7%) and 2001 and 2002 (60.9%). Stillbirth, neonatal and infant mortality rates declined by 52% (RR 0.48, 95% confidence interval [CI] 0.36-0.63), 32% (RR 0.68, 95% CI 0.58-0.80), and 38% (RR 0.62, 95% CI 0.53-0.71), respectively, between 1990 and 1991 and 2001 and 2002. The increase in triplet births at <34 weeks was not associated with the stillbirth decline, but was associated with an excess 14% and 12% increase in neonatal and infant deaths, respectively.

Conclusion

Our findings suggest that the increase in triplet births at <34 weeks' gestation is not associated with changes in triplet stillbirths, but is associated with increases in triplet neonatal and infant mortality.

Section snippets

Data source

Data on triplet live births, stillbirths and neonatal and infant mortality were obtained from the National Centers for Health Statistics (NCHS) linked birth/infant death files collected from 1990 to 2002.15 The NCHS links infant deaths (within the first year) to corresponding live births using data provided by individual states and the District of Columbia under the Vital Statistics Cooperative Program. The linked data files contain information on stillbirth, neonatal and infant mortality.

Results

There were a total of 73,186 triplet stillbirths and live births in the United States between 1990 and 2002. We sequentially excluded fetuses with missing data on gestational age (n = 1124), those that were delivered at <22 weeks' gestation, and fetuses that weighed <500 g (n = 5076). These exclusions left us with 66,986 triplet births for analysis. Of these stillbirths and live births, 5724 births occurred during the period of 1990 to 1991 and 13,837 births during the period of 2001 to 2002.

Comment

The present study shows the striking increase in triplet births in the United States. Concurrently, rates of triplet births at <34 weeks have significantly increased over the last decade. During the same period, overall rates of stillbirth and neonatal and infant mortality have decreased.

Our findings of overall decreasing rates in crude stillbirths and infant mortality among triplet births concur with those reported among US twin births.10, 13 They, however, differ from those reported by Joseph

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    Drs Getahun and Ananth are partially supported through a grant (R01-HD038902) from the National Institutes of Health awarded to Dr Ananth. Dr Amre is supported by a salary award from the Fonds de la recherché en Santé Quebéc.

    Reprints not available from the authors. Address correspondence to Darios Getahun, MD, MPH, Division of Epidemiology and Biostatistics, Department of Obstetrics, Gynecology, and Reproductive Sciences, UMDNJ-Robert Wood Johnson Medical School, 125 Paterson Street, New Brunswick, NJ 08901-1977.

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