School of Public Health, Curtin University, Perth, WA, Australia.
School of Public Health, Texas A&M University, College Station, TX, USA.
BJOG. 2021 Jun;128(7):1134-1143. doi: 10.1111/1471-0528.16606. Epub 2020 Dec 14.
To investigate the effect of interpregnancy interval (IPI) on preterm birth (PTB) according to whether the previous birth was preterm or term.
Cohort study.
USA (California), Australia, Finland, Norway (1980-2017).
Women who gave birth to first and second (n = 3 213 855) singleton livebirths.
Odds ratios (ORs) for PTB according to IPIs were modelled using logistic regression with prognostic score stratification for potential confounders. Within-site ORs were pooled by random effects meta-analysis.
PTB (gestational age <37 weeks).
Absolute risk of PTB for each IPI was 3-6% after a previous term birth and 17-22% after previous PTB. ORs for PTB differed between previous term and preterm births in all countries (P-for-interaction ≤ 0.001). For women with a previous term birth, pooled ORs were increased for IPI <6 months (OR 1.50, 95% CI 1.43-1.58); 6-11 months (OR 1.10, 95% CI 1.04-1.16); 24-59 months (OR 1.16, 95% CI 1.13-1.18); and ≥ 60 months (OR 1.72, 95%CI 1.60-1.86), compared with 18-23 months. For previous PTB, ORs were increased for <6 months (OR 1.30, 95% CI 1.18-1.42) and ≥60 months (OR 1.29, 95% CI 1.17-1.42), but were less than ORs among women with a previous term birth (P < 0.05).
Associations between IPI and PTB are modified by whether or not the previous pregnancy was preterm. ORs for short and long IPIs were higher among women with a previous term birth than a previous PTB, which for short IPI is consistent with the maternal depletion hypothesis. Given the high risk of recurrence and assuming a causal association between IPI and PTB, IPI remains a potentially modifiable risk factor for women with previous PTB.
Short versus long interpregnancy intervals associated with higher ORs for preterm birth (PTB) after a previous PTB.
根据前次分娩是否为早产，探讨孕次间间隔（interpregnancy interval，IPI）对早产（preterm birth，PTB）的影响。
队列研究。
美国（加利福尼亚州）、澳大利亚、芬兰、挪威（1980-2017 年）。
首次分娩和第二次分娩（n=3 213 855）单胎活产的女性。
采用逻辑回归模型，对不同 IPI 与 PTB 发生风险的比值比（odds ratio，OR）进行分析，并对潜在混杂因素进行预后评分分层。采用随机效应荟萃分析对各研究点的 OR 进行汇总。
PTB（胎龄<37 周）。
在前次足月产分娩后，每个 IPI 导致 PTB 的绝对风险为 3%-6%；而在前次早产分娩后，这一风险为 17%-22%。所有国家中，前次足月产与早产分娩之间的 PTB 发生风险 OR 存在差异（P 交互值均<0.001）。在前次足月产分娩的女性中，与 18-23 个月 IPI 相比，<6 个月（OR 1.50，95%CI 1.43-1.58）、6-11 个月（OR 1.10，95%CI 1.04-1.16）、24-59 个月（OR 1.16，95%CI 1.13-1.18）和≥60 个月（OR 1.72，95%CI 1.60-1.86）的 IPI 导致 PTB 的 OR 升高。而在前次早产分娩的女性中，<6 个月（OR 1.30，95%CI 1.18-1.42）和≥60 个月（OR 1.29，95%CI 1.17-1.42）的 OR 升高，但低于前次足月产分娩的 OR（P<0.05）。
孕次间间隔与 PTB 之间的关联受前次妊娠是否为早产的影响。与前次足月产分娩相比，前次早产分娩后较短和较长的 IPI 与较高的 OR 相关，而对于较短的 IPI，这种关联与母体耗竭假说一致。鉴于复发风险较高且假设 IPI 与 PTB 之间存在因果关系，IPI 仍然是具有前次 PTB 史女性的一个潜在可改变的危险因素。
与前次足月产分娩相比，前次早产分娩后较短和较长的孕次间间隔与更高的早产风险相关。
