BACKGROUND The average age at first birth is steadily increasing in developed countries; however, demographic shifts in maternal age at childbearing have not occurred in isolation. While temporal increases in adverse pregnancy outcomes are typically attributed to increases in maternal age, little is known about how maternal health status has changed across maternal age, period of delivery, and birth cohort. METHODS Natality files were used to identify primiparous women delivering liveborn, singleton infants in the USA in 1989, 1994, 1999, 2004, 2009, and 2014 (n = 6,857,185). Age-period-cohort models using the intrinsic estimator adjusted for temporal trends in smoking and gestational weight gain were used to quantify temporal changes in the rates of pre-existing (chronic hypertension, pre-existing diabetes) and pregnancy-associated (pregnancy-associated hypertension, gestational diabetes, eclampsia) diseases. Log-linear models were used to model the impact of temporal changes on preterm birth, small, and large for gestational age (SGA/LGA) births. RESULTS Significant period effects resulted in temporal increases in the rate of chronic hypertension, pregnancy-associated hypertension, and gestational diabetes, and a significant decrease in the rate of eclampsia. These observed period effects were associated with a 10.6% increase in the rate of SGA and a 7.1% decrease in LGA. Had the rate of pre-existing and pregnancy-associated diseases remained static over this time period, the rate of preterm birth would have increased by 5.9%, but instead only increased by 4.4%. CONCLUSIONS Independent of changes in the incidence of pre-existing and pregnancy-associated diseases as women age, the obstetric population is becoming less healthy over time. This is important, as these changes have a direct negative impact on short-term obstetric outcomes and women's long-term health.

中文翻译：

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初产妇女在既往疾病和妊娠相关疾病中的年龄段队列影响。

背景技术发达国家的初生平均年龄正在稳步增长。然而，育龄妇女的人口结构变化并不是孤立发生的。尽管不良妊娠结局的暂时性增加通常归因于孕产妇年龄的增加，但人们对孕产妇健康状况如何随着孕产妇年龄，分娩期和出生队列的变化知之甚少。方法使用出生档案来识别1989、1994、1999、2004、2009和2014年在美国分娩的初生妇女，其中n = 6,857,185。使用针对吸烟和孕期体重增加的时间趋势进行了调整的内在估计量的年龄组模型，用于量化既往发生率（慢性高血压，先前患有的糖尿病）和与妊娠相关的疾病（与妊娠相关的高血压，妊娠糖尿病，子痫病）。使用对数线性模型来模拟时间变化对胎龄（SGA / LGA）出生的大小早产的影响。结果显着的时期效应导致慢性高血压，妊娠相关性高血压和妊娠糖尿病的发生率暂时升高，子痫率显着下降。这些观察到的周期影响与SGA率增加10.6％和LGA减少7.1％有关。如果在此期间既存疾病和与妊娠相关的疾病的发生率保持不变，那么早产率将增加5.9％，而只会增加4.4％。结论随着女性年龄的增长，与既存疾病和妊娠相关疾病的发生率变化无关，随着时间的推移，产科人群的健康状况变得越来越差。这很重要，因为这些变化对短期的产科结局和妇女的长期健康有直接的负面影响。