Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts.
Department of Family Practice, University of British Columbia, Vancouver, British Columbia, Canada.
JAMA Intern Med. 2018 Dec 1;178(12):1661-1670. doi: 10.1001/jamainternmed.2018.4696.
Interpregnancy intervals shorter than 18 months are associated with higher risks of adverse pregnancy outcomes. It is currently unknown whether short intervals are associated with increased risks among older women to the same extent as among younger women.
To evaluate whether the association between short interpregnancy (delivery to conception) interval and adverse pregnancy outcomes is modified by maternal age.
DESIGN, SETTING, AND PARTICIPANTS: A population-based cohort study conducted in British Columbia, Canada, evaluated women with 2 or more singleton pregnancies from 2004 to 2014 with the first (index) pregnancy resulting in a live birth. Data analysis was performed from January 1 to July 20, 2018.
Risks of maternal mortality or severe morbidity (eg, mechanical ventilation, blood transfusion >3 U, intensive care unit admission, organ failure, death), small-for-gestational age (<10th birthweight percentile for gestational age and sex), fetal and infant composite outcome (stillbirth, infant death, <third birthweight percentile for gestational age and sex, delivery <28 weeks), and spontaneous and indicated preterm delivery. Risks of each outcome for 3- to 24-month interpregnancy intervals were estimated, according to maternal age at index birth (20-34 and ≥35 years). Adjusted risk ratios (aRRs) comparing predicted risks at 3-, 6-, 9-, and 12-month intervals with risks at 18-month intervals for each age group were calculated. The potential role of other factors explaining any differences (unmeasured confounding) was examined in several sensitivity analyses.
Among 148 544 pregnancies, maternal mortality or severe morbidity risks were increased at 6-month compared with 18-month interpregnancy intervals for women aged 35 years or older (0.62% at 6 months vs 0.26% at 18 months; aRR, 2.39; 95% CI, 2.03-2.80), but not for women aged 20 to 34 years (0.23% at 6 months vs 0.25% at 18 months; aRR, 0.92; 95% CI, 0.83-1.02). Increased adverse fetal and infant outcome risks were more pronounced for women aged 20 to 34 years (2.0% at 6 months vs 1.4% at 18 months; aRR, 1.42; 95% CI, 1.36-1.47) than women 35 years or older (2.1% at 6 months vs 1.8% at 18 months; aRR, 1.15; 95% CI, 1.01-1.31). Risks of spontaneous preterm delivery at 6-month interpregnancy intervals were increased for women 20 to 34 years old (5.3% at 6 months vs 3.2% at 18 months; aRR, 1.65; 95% CI, 1.62-1.68) and to a lesser extent for women 35 years or older (5.0% at 6 months vs 3.6% at 18 months; aRR, 1.40; 95% CI, 1.31-1.49). Modest increases in risks of small-for-gestational age and indicated preterm delivery at short intervals did not vary meaningfully by maternal age. Sensitivity analyses suggested that observed associations were not fully explained by unmeasured confounding.
The findings of this study suggest that short interpregnancy intervals are associated with increased risks for adverse pregnancy outcomes for women of all ages.
重要性：妊娠间隔时间短于 18 个月与不良妊娠结局的风险增加相关。目前尚不清楚在年龄较大的女性中，短间隔是否与年轻女性一样，增加了发生风险的程度。
目的：评估在妊娠间隔（分娩至受孕）较短的情况下，产妇年龄是否会影响不良妊娠结局的发生。
设计、设置和参与者：本研究是一项基于人群的队列研究，在加拿大不列颠哥伦比亚省进行，纳入了 2004 年至 2014 年期间有 2 次或以上单胎妊娠且首次（索引）妊娠为活产的女性。数据分析于 2018 年 1 月 1 日至 7 月 20 日进行。
主要结果和测量：根据索引分娩时的母亲年龄（20-34 岁和≥35 岁），评估了产妇死亡率或严重发病率（如机械通气、输血>3U、入住重症监护病房、器官衰竭、死亡）、小于胎龄儿（<第 10 个胎龄和性别出生体重百分位）、胎儿和婴儿复合结局（死胎、婴儿死亡、<第 3 个胎龄和性别出生体重百分位、<28 周分娩）以及自发性和指征性早产的风险。根据母亲年龄，计算了 3-24 个月妊娠间隔的每个结局的风险，并与 18 个月间隔的风险进行了比较。对于每个年龄组，计算了预测风险在 3、6、9 和 12 个月时与 18 个月间隔时的风险的调整风险比（aRR）。通过几个敏感性分析，检查了其他因素（未测量的混杂因素）解释任何差异的作用。
结果：在 148544 例妊娠中，与 18 个月的妊娠间隔相比，35 岁或以上的女性在 6 个月时的产妇死亡率或严重发病率风险增加（6 个月时为 0.62%，18 个月时为 0.26%；aRR，2.39；95%CI，2.03-2.80），但 20-34 岁的女性则不然（6 个月时为 0.23%，18 个月时为 0.25%；aRR，0.92；95%CI，0.83-1.02）。对于 20-34 岁的女性，不良胎儿和婴儿结局的风险增加更为明显（6 个月时为 2.0%，18 个月时为 1.4%；aRR，1.42；95%CI，1.36-1.47），而对于 35 岁或以上的女性则不然（6 个月时为 2.1%，18 个月时为 1.8%；aRR，1.15；95%CI，1.01-1.31）。对于 20-34 岁的女性，6 个月妊娠间隔时自发性早产的风险增加（6 个月时为 5.3%，18 个月时为 3.2%；aRR，1.65；95%CI，1.62-1.68），而对于 35 岁或以上的女性则不那么明显（6 个月时为 5.0%，18 个月时为 3.6%；aRR，1.40；95%CI，1.31-1.49）。短间隔时小胎龄儿和指征性早产风险的适度增加与产妇年龄无明显关系。敏感性分析表明，观察到的关联并未完全由未测量的混杂因素解释。
结论和相关性：本研究结果表明，妊娠间隔时间较短与所有年龄段女性的不良妊娠结局风险增加有关。
