OBJECTIVE To measure contemporary trends in the prevalence of short interpregnancy interval (IPI) births in the United States. METHODS We conducted a repeated cross-sectional analysis using 2016-2022 natality data from the National Vital Statistics System. We included all singleton live births to individuals with at least one prior live birth. We examined trends over time in short IPIs less than 18 months, as well as for specific durations within this time frame (less than 6 months, 6-11 months, and 12-17 months), using linear probability models that estimated changes in the prevalence of each IPI duration over time. We then estimated the prevalence of each short IPI duration by maternal race and ethnicity, socioeconomic characteristics (age, education, insurance payer at delivery), and geography (U.S. census region, state of residence). RESULTS The study sample included 14,770,411 singleton live births to individuals with at least one prior live birth in 2016-2022. Roughly a third (29.8%) of births had an overall IPI of less than 18 months (5.0% less than 6 months, 11.0% 6-11 months, and 13.8% 12-17 months). For IPIs less than 6 months, a slight statistical decline in prevalence was identified over the study period in unadjusted and adjusted models (adjusted annual percentage point change -0.02, 95% CI, -0.03 to -0.02). Slight statistical increases in the prevalence of IPIs of 6-11 and 12-17 months were identified in unadjusted models but were no longer significant and reversed direction in adjusted models, respectively. Long-standing inequities in the distribution of the shortest IPIs (less than 6 months) were stable compared with prior work across the indicators examined in this study. CONCLUSION Overall, it appears the prevalence of short IPIs has remained stable between 2016 and 2022.

中文翻译：

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2016-2022 年美国短孕间隔生育趋势。


目的 衡量美国短妊娠间隔 （IPI） 分娩患病率的当代趋势。方法 我们使用来自国家生命统计系统的 2016-2022 年出生数据进行了重复横断面分析。我们纳入了所有单例活产儿，这些单例活产儿是至少有一次既往活产的个体。我们使用线性概率模型研究了少于 18 个月的短期 IPI 随时间的变化，以及此时间范围内特定持续时间（少于 6 个月、6-11 个月和 12-17 个月）的趋势，这些模型估计了每个 IPI 持续时间随时间的变化。然后，我们根据母体种族和民族、社会经济特征（年龄、教育程度、分娩时的保险支付人）和地理位置（美国人口普查地区、居住州）估计了每次短期 IPI 持续时间的患病率。结果研究样本包括 14,770,411 例单例活产婴儿，这些单例活产婴儿在 2016-2022 年至少有一次活产。大约三分之一 （29.8%） 的新生儿的总体 IPI 小于 18 个月（5.0% 小于 6 个月，11.0% 6-11 个月，13.8% 12-17 个月）。对于少于 6 个月的 IPI，在研究期间，在未调整和调整的模型中发现患病率略有统计下降（调整后的年度百分点变化 -0.02,95% CI，-0.03 至 -0.02）。在未调整的模型中发现 6-11 个月和 12-17 个月的 IPI 患病率略有统计增加，但在调整后的模型中不再显着且方向相反。与本研究中检查的指标的先前工作相比，最短 IPI（少于 6 个月）分配中长期存在的不平等是稳定的。 结论 总体而言，短期 IPI 的流行率在 2016 年至 2022 年期间似乎保持稳定。