General Obstetrics and Gynecology: Obstetrics
Higher rate of stillbirth at the extremes of reproductive age: A large nationwide sample of deliveries in the United States

https://doi.org/10.1016/j.ajog.2005.08.038Get rights and content

Objective

The purpose of this study was to assess the effect of maternal age on the rate of stillbirth in a large, nationwide sample of deliveries in the United States.

Study design

Data were derived from the Nationwide Inpatient Sample for the years 1995 through 2002. With the use of ICD-9 codes, the rate of stillbirth was determined as a function of maternal age. Multivariate regression analysis was used to assess the effect of maternal age on the odds of stillbirth, with adjustment for multiple known risk factors for stillbirth.

Results

There were 5,874,203 deliveries that were identified for analysis. The unadjusted rate of stillbirth was elevated for teenagers and for women aged ≥35 years. In the multivariate analysis, compared with women 20 to 34 years old, women who were ≤19 years old were more likely to have a pregnancy outcome of stillbirth (odds ratio, 1.11; 95% CI, 1.08-1.14), as were women who were 35 to 39 years old (odds ratio, 1.28; 95% CI, 1.24-1.32) and women who were ≥40 years old (odds ratio, 1.72; 95% CI, 1.63-1.81).

Conclusion

The extremes of maternal age are associated with an increased risk for stillbirth, even after adjustment for a large number of known predisposing conditions.

Section snippets

Methods

Data for this study were obtained from the Nationwide Inpatient Sample for the years 1995 through 2002. The Nationwide Inpatient Sample is maintained as part of the Healthcare Utilization Project of the Agency for Healthcare Quality and Research. It represents an approximate 20% stratified sample of all patients who are admitted at non-federal hospitals each year. Five hospital characteristics, geographic region, ownership, location (urban or rural), teaching status, and bed size are used for

Results

We identified 5,874,203 patients who were hospitalized for a delivery with a known outcome; 74.6% of the women were 20 to 34 years old; 12.1% of the women were ≤19 years old; 11.1% of the women were 35 to 39 years old, and 2.2% of the women were ≥40 years old. Table I shows the rates of various potential risk factors for stillbirth and patient demographic information, according to maternal age group at the time of delivery. The rate of multiple gestation rose with advancing age, reaching a high

Comment

We report the effect of maternal age on the incidence of stillbirth for 5,874,203 deliveries, which represents a sample of approximately 20% of all deliveries in the United States for the years 1995 to 2002. We found that the extremes of maternal reproductive age predicted a higher risk of stillbirth and that this effect persisted even after adjustment for several maternal, placental, and fetal risk factors. Further, we showed that the stillbirth rate was relatively stable during the study

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