School of Public Health, The University of Queensland, Herston, Queensland, Australia.
Department of Biostatistics and Epidemiology, School of Health, Kerman University of Medical Sciences, Kerman, Iran.
Birth. 2022 Dec;49(4):728-740. doi: 10.1111/birt.12638. Epub 2022 Mar 31.
Short and long intervals between successive births are associated with adverse birth outcomes, especially in low-income and middle-income countries, yet the birth intervals in high-income countries remain relatively understudied. The aim was to examine maternal factors associated with birth intervals in Australia.
The sample comprised 6130 participants in the Australian Longitudinal Study on Women's Health who were born in 1973-1978, had two or more births, and responded to regular surveys between 1996 and 2018. Interbirth interval (IBI) was defined as the time between successive live births. Maternal factors were examined using accelerated failure time models.
For women with only two births (n = 3802), the median time to the second birth was 34.0 months (IQR 23.1, 46.2) with shorter IBI associated with higher socioeconomic status (eg, university education (31.9 months), less income stress (31.1)), and longer IBI associated with age over 35 (39.7), fair/poor health (43.0), untreated fertility problems (45.5), miscarriage (39.4), or abortion (41.0). For women with three or more births (n = 2328), the median times to the second and third births were 31.2 months (19.9, 42.1) and 36.5 months (25.3, 50.1), respectively; some factors were consistent between the first IBI and second IBI (eg, university education and being married were associated with shorter IBI), whereas income stress was associated with longer first IBI but not with second IBI.
Understanding maternal factors associated with birth intervals in a high-income country like Australia may enable more nuanced tailoring of guidelines for prepregnancy care.
连续分娩之间的短间隔和长间隔与不良分娩结局有关，尤其是在低收入和中等收入国家，但高收入国家的分娩间隔仍相对研究不足。本研究旨在探讨澳大利亚母婴因素与分娩间隔的关系。
本研究样本来自澳大利亚妇女健康纵向研究，共纳入 1973-1978 年出生、生育两次及以上且在 1996 年至 2018 年期间定期参加调查的 6130 名参与者。将产次间隔（interbirth interval，IBI）定义为连续活产之间的时间。采用加速失效时间模型来研究母婴因素与 IBI 的关系。
对于仅有两次分娩的女性（n=3802），第二次分娩的中位时间为 34.0 个月（IQR 23.1，46.2），较短的 IBI 与较高的社会经济地位相关（如，大学教育（31.9 个月），较低的收入压力（31.1）），而较长的 IBI 与年龄超过 35 岁（39.7）、健康状况一般/较差（43.0）、未经治疗的生育问题（45.5）、流产（39.4）或堕胎（41.0）相关。对于生育三次及以上的女性（n=2328），第二次和第三次分娩的中位时间分别为 31.2 个月（19.9，42.1）和 36.5 个月（25.3，50.1）；一些因素在首次 IBI 和第二次 IBI 之间具有一致性（如，大学教育和已婚与较短的 IBI 相关），而收入压力与较长的首次 IBI 相关，但与第二次 IBI 无关。
了解像澳大利亚这样的高收入国家母婴因素与分娩间隔的关系，可能有助于更细致地调整孕前保健指南。
